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  • 251. Carvalho, D. M. D.
    et al.
    Lahtinen, M. H.
    Bhattarai, M.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mikkonen, K. S.
    Active role of lignin in anchoring wood-based stabilizers to the emulsion interface2021In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 23, no 22, p. 9084-9098Article in journal (Refereed)
    Abstract [en]

    Hemicellulose-rich wood extracts show efficient capacity to adsorb at emulsion interfaces and stabilize them. Their functionality is enhanced by lignin moieties accompanying the hemicellulose structures, in the form of lignin-carbohydrate complexes (LCCs) and, potentially, other non-covalent associations. The formation and stability of emulsions is determined by their interfacial regions. These are largely unexplored assemblies when formed from natural stabilizers with a complex chemical composition. Understanding the structure of the interfacial region could facilitate both designing the extraction processes of abundant biomasses and unraveling a valuable industrial application potential for the extracts. Herein, we characterized the LCCs from the interface of oil-in-water emulsions stabilized by galactoglucomannan (GGM) or glucuronoxylan (GX)-rich wood extracts, using two-dimensional nuclear magnetic resonance (NMR) spectroscopy analysis. The type of covalent linkage between residual lignin and hemicelluloses determined their partitioning between the continuous and interfacial emulsion phases. Benzylether structures, only found in the interface, were suggested to participate in the physical stabilization of the emulsion droplets. In turn, the phenylglycosides, preferentially observed in the continuous phase, were suggested to interact with adsorbed stabilizers by electrostatic interaction. More hydrophobic lignin structures, such as guaiacyl lignin type, dibenzodioxocin substructures, and certain end groups also contributed to droplet stabilization. The elucidation of such attributes is of paramount importance for the biorefinery industry, enabling the optimization of extraction processes for the preparation of wood-based stabilizers and designed interfaces for novel and sustainable emulsion systems.

  • 252.
    Castro, Daniele Oliveira
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. MoRe Research Örnsköldsvik AB, Örnsköldsvik, Sweden.
    Karim, Zoheb
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. MoRe Research Örnsköldsvik AB, Örnsköldsvik, Sweden.
    Medina, Lilian
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Häggström, J. -O
    Carosio, F.
    Svedberg, A.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Berglund, Lars A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    The use of a pilot-scale continuous paper process for fire retardant cellulose-kaolinite nanocomposites2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, p. 215-224Article in journal (Refereed)
    Abstract [en]

    Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications.

  • 253. Cataldi, A.
    et al.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Deflorian, F.
    Pegoretti, A.
    A comparison between micro- and nanocellulose-filled composite adhesives for oil paintings restoration2015In: Nanocomposites, E-ISSN 2055-0332, Vol. 1, no 4, p. 195-203Article in journal (Refereed)
    Abstract [en]

    Cellulose nanocrystals (CNC) and microcrystals (CMC) were selected as reinforcing fillers for poly(2-ethyl-2-oxazoline), a water-soluble thermoplastic adhesive widely used in the restoration of oil paintings. Thin composite films containing 5, 10, and 30 wt% of CNC or CMC were produced by solution mixing and casting. UV-vis spectroscopy showed how CNC preserved the adhesive transparency even at the highest CNC content, while for CMC, a progressive loss of transparency was observed. Thermal analysis evidenced a progressive increase of the glass transition temperature of the polymer matrix induced by CNC, while no effects were observed for CMC. Both micro- and nanocellulose were able to improve the elastic modulus and reduce the thermal expansion coefficient and creep compliance of the adhesive, with effects more pronounced for CNC nanoparticles. Finally, single-lap shear test on bonded ancient oil painting substrates confirmed the improved dimensional stability of the joint imparted by CNC in the adhesive under both quasi-static and creep conditions. 

  • 254.
    Cattaruzza, Martina
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Fang, Yuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Liu, Fang
    Division of Materials and Manufacture, Department of Industrial and Materials Science, Chalmers University of Technology, SE-412 Gothenburg 96 Sweden.
    Johansson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Hybrid polymer-liquid lithium ion electrolytes: effect of porosity on the ionic and molecular mobility2023In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 11, no 13, p. 7006-7015Article in journal (Refereed)
    Abstract [en]

    Alternative electrolyte systems such as hybrid electrolytes are much sought after to overcome safety issues related to liquid electrolytes in lithium ion batteries (LIBs). Hybrid solid-liquid electrolytes (HEs) like the heterogeneous structural battery electrolyte (SBE) consist of two discrete co-existing phases prepared by polymerization-induced phase separation: one solid polymer phase providing mechanical integrity and the other one a percolating liquid ion-conducting phase. The present work investigates the ion and the solvent mobility in a series of HEs using morphological, electrochemical impedance and NMR spectroscopic methods. All the dried HEs exhibit a porous structure with a broad pore size distribution stretching down to <10 nm diameter. Penetration of the individual components of the solution, that is the ions and the solvent, in the solid polymer phase is demonstrated. Yet, it is the pores that are the main ion conduction channels in the liquid-saturated HEs and, in general, translational mobility is strongly dependent on the volume fraction and size of the pores and, thereby, on the initial liquid electrolyte content. We also observe that the translational mobility of solvent and the ions vary differently with the pore volume fraction. This finding is explained by the presence of small mesopores where the mobility strongly depends on the specific interactions of the molecular constituent with the pore wall. These interactions are inferred to be stronger for the EC/PC solvent than for the ions. This study shows how the morphology and the chemical composition of HEs affect the ionic and molecular transport in the system.

  • 255.
    Cederholm, Linnea
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Thermodynamic Toolkit for Chemical Recycling to Monomer2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The design of polymeric materials for a circular economy is, to a largeextent, a challenge of thermodynamics. The work presented in this thesishas explored the thermodynamic features of ring-opening polymerizationand ring-closing depolymerization, to develop polymeric materials andrecycling strategies for chemical recycling to monomer.First, statistical copolymerization was explored as a tool for internal endcapping,in order to enhance the thermodynamic stability of an aliphaticpolyester. However, a drawback of the improved thermodynamic stabilitywas a negative impact on the recyclability. Next, the solvents effect on thethermodynamic equilibrium was studied. It was found that, apart from thedecreasing effect that dilution had on the ceiling temperature as aconsequence of the increased entropy, the properties of the solventstrongly influenced the equilibrium. This was studied for three differentsix-membered cyclic monomers, two lactones and one carbonate, whereceiling temperature of the more polar monomers where more influencedby the solvent effect. This solvent effect was used to realize chemicalrecycling to monomer of polylactide via ring-closing depolymerization,with high conversion and high selectivity. Finally, three different A–B–Atype block copolymers were designed. The influence of block componentson the mechanical properties and recyclability was investigated, showingthat the midblock chemical structure had a strong impact on the Young’smodulus, the elongation at break, as well as the on the ring-closingdepolymerization behavior.

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  • 256.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Chemical recycling to monomer: thermodynamic and kinetic control of the ring-closing depolymerization of aliphatic polyesters and polycarbonatesManuscript (preprint) (Other academic)
  • 257.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Chemical recycling to monomer: thermodynamic and kinetic control of the ring-closing depolymerization of aliphatic polyesters and polycarbonates2023In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 14, no 28, p. 3270-3276Article in journal (Refereed)
    Abstract [en]

    The thermodynamic equilibrium between ring-opening polymerization and ring-closing depolymerization is influenced by monomer-solvent-polymer interactions, an effect that can be utilized to promote chemical recycling to monomer. Here, the influence of monomer structure on this solvent effect has been investigated, showing that the chemical structure of the monomer influences the power of the solvent to supress the ceiling temperature. The study also demonstrates how catalyst selectivity can be utilized to obtain selective ring-closing depolymerization of one component of a polymer blend, even when the thermodynamics dictate otherwise.

  • 258.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Design for recycling: polyester and polycarbonate based A-B-A block copolymers and their recyclability back to monomerManuscript (preprint) (Other academic)
  • 259.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Design for Recycling: Polyester- and Polycarbonate-Based A-B-A Block Copolymers and Their Recyclability Back to Monomers2023In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 56, no 10, p. 3641-3649Article in journal (Refereed)
    Abstract [en]

    Chemical recycling to monomers (CRMs) of A-B-Ablockcopolymers is governed by the chemical structure and thereby the thermodynamicbehavior of different block constituents. Here, we show how a thermodynamictoolkit based on a cyclic monomer structure and solvent propertiescan be utilized in the design of recyclable A-B-A blockcopolymers with varying material properties. By combining four cyclicmonomers lactide, epsilon-decalactone, 2,2-diethyltrimethylene carbonate,and trimethylene carbonate, three different block copolymers werecreated, suitable for different CRM scenarios. The chemical structureof the soft midblock (epsilon-decalactone or trimethylene carbonate)appeared to have a critical impact both on the ring-closing depolymerizationbehavior and mechanical properties, where changing from a polyesterto a polycarbonate soft block increased Young's modulus from14 to 200 MPa. Hence, this work demonstrates the complexity as wellas the opportunities in the design of macromolecular structures fora circular economy.

  • 260.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Turning natural delta-lactones to thermodynamically stable polymers with triggered recyclability2020In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 11, no 30, p. 4883-4894Article in journal (Refereed)
    Abstract [en]

    To extend the use of naturally occurring substituted delta-lactones within the polymer field, their commonly low ceiling temperature and thereby challenging equilibrium behavior needs to be addressed. A synthetic strategy to control the polymerization thermodynamics was therefore developed. This was achieved by copolymerizing delta-decalactone (delta DL) with either epsilon-decalactone (epsilon DL) or epsilon-caprolactone (epsilon CL) at room temperature (RT), with diphenyl phosphate (DPP) as catalyst. The thermodynamic stability of P delta DL-co-epsilon DL and P delta DL-co-epsilon CL increased with increased comonomer ratio in the feed, to 10% and 30% monomeric epsilon DL, respectively, at 110 degrees C. This is in contrast to the P delta DL homopolymer, which under the same conditions depolymerized to 70% monomeric delta DL at equilibrium. The copolymers' macromolecular structure, originating from the copolymerization kinetics, was found to be the crucial factor to mitigate delta DLs equilibrium behavior. To close the loop, designing materials for a circular economy, the recycling of P delta DL-co-epsilon DL was demonstrated, by reaction with benzyl alcohol (BnOH) as an external nucleophile, leading to cyclic monomers or dimers with BnOH at high yield.

  • 261.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    “Like Recycles Like”: Selective Ring-Closing Depolymerization of Poly(L-Lactic Acid) to L-Lactide2022In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 61, no 33, article id e202204531Article in journal (Refereed)
    Abstract [en]

    Chemical recycling of poly(L-lactic acid) to the cyclic monomer L-lactide is hampered by low selectivity and by epimerization and elimination reactions, impeding its use on a large scale. The high number of side reactions originates from the high ceiling temperature (Tc) of L-lactide, which necessitates high temperatures or multistep reactions to achieve recycling to L-lactide. To circumvent this issue, we utilized the impact of solvent interactions on the monomer–polymer equilibrium to decrease the Tc of L-lactide. Analyzing the observed Tc in different solvents in relation to their Hildebrand solubility parameter revealed a “like recycles like” relationship. The decreased Tc, obtained by selecting solvents that interact strongly with the monomer (dimethyl formamide or the green solvent γ-valerolactone), allowed chemical recycling of high-molecular-weight poly(L-lactic acid) directly to L-lactide, within 1–4 h at 140 °C, with &gt;95 % conversion and 98–99 % selectivity. Recycled L-lactide was isolated and repolymerized with high control over molecular weight and dispersity, closing the polymer loop. 

  • 262.
    Cederholm, Linnea
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Xu, Yunsheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Tagami, Ayumu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Microwave processing of lignin in green solvents: A high-yield process to narrow-dispersity oligomers2020In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 145, article id 112152Article in journal (Refereed)
    Abstract [en]

    Functional narrow-dispersity kraft lignin oligomers in high-yields were produced by a combined microwave-assisted extraction/degradation process. The process took place under mild non-catalytic conditions, in green solvents, and moderate temperatures (80 -160 degrees C). High yields, i.e., 63 % and 64 %, of lignin oligomers with narrow dispersity were obtained after only 40 min microwave processing in methanol and ethanol, respectively. The ethanol-soluble yield increased substantially after microwave processing as compared to samples extracted by liquid-solid solvent-extraction. This increase was mainly ascribed to the cleavage of beta-O-4 linkages, as indicated by semiquantitative 2D-HSQC NMR. Under the corresponding conditions in methanol, the yields after microwave processing were similar to those obtained by liquid-solid solvent-extraction. The difference is likely ascribed to the different reactivities of the solvents as O-alkylation agents. Furthermore, the obtained lignin fractions had high functionality, as shown by hydroxyl-group quantification through P-31-NMR. This, along with the narrow dispersity and rich aromatic structure, makes these oligomers interesting precursors for future thermoset syntheses.

  • 263. Ceresino, E. B.
    et al.
    Kuktaite, R.
    Sato, H. H.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Johansson, E.
    Impact of gluten separation process and transglutaminase source on gluten based dough properties2019In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 87, p. 661-669Article in journal (Refereed)
    Abstract [en]

    This study evaluated the effect of the wheat gluten (WG) separation process and transglutaminase (TG) microbial source on WG dough quality, and opportunities to use these factors to tailor dough quality. Two types of gluten (harshly and mildly separated), two types of TG (commercial and novel SB6), and three TG concentrations were evaluated for effects on dough mixing properties, protein structure and solubility. Mildly separated gluten improved dough development parameters, resulting into higher values of most compared with harshly separated gluten. Despite more strongly cross-linked proteins being found in the harshly separated gluten, both gluten types showed similar levels of cross-linking at optimum mixing time, although differences in the secondary protein structure were indicated. Thus, disulfide-sulfhydryl exchange reactions were found to be promoted by mixing, although restrictions on establishment of new bonds because of prior cross-links in the material were clearly indicated. Degree of polymerization in doughs made from mildly separated gluten increased to varying extents with TG addition depending on TG source and concentration. Thus, for the first time, we show that an appropriate combination of WG separation procedure and TG source can be used to tailor gluten dough end-use properties.

  • 264.
    Ceresino, Elaine Berger
    et al.
    Swedish Univ Agr Sci, Dept Plant Breeding, Box 101, SE-23053 Alnarp, Sweden..
    Kuktaite, Ramune
    Swedish Univ Agr Sci, Dept Plant Breeding, Box 101, SE-23053 Alnarp, Sweden..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Sato, Helia Harumi
    Univ Estadual Campinas, Sch Food Engn, Dept Food Sci, Campinas, Brazil..
    Johansson, Eva
    Swedish Univ Agr Sci, Dept Plant Breeding, Box 101, SE-23053 Alnarp, Sweden..
    Processing conditions and transglutaminase sources to "drive" the wheat gluten dough quality2020In: Innovative Food Science & Emerging Technologies, ISSN 1466-8564, E-ISSN 1878-5522, Vol. 65, article id 102439Article in journal (Refereed)
    Abstract [en]

    Gluten proteins are highly impacting the quality of various gluten-based products, and transglutaminases (TGs) are used to influence the protein cross-linking. In this study we monitored the interplay of "harsh" and "mild" gluten processing for dough mixing and pasta-like sheet production and TGs from a commercial and newly sourced bacteria (SB6). Despite the harshly separated gluten presenting strongly cross-linked proteins in the beginning of the mixing, similar levels of polymerization were achieved at the optimum mixing time but with differences in the secondary protein structure. TG addition increased polymerization in wheat doughs, possibly as a result of increased glutenin polymerization, while gliadins become more soluble with SB6. This enzyme also dramatically increased polymerization in mild gluten. These results show that an adequate investigation when using TGs and gluten from various origins is necessary to adequately predict the quality in various gluten-based products, thus, of great relevance to the food industry. Industrial relevance: Currently, there is a mounting trend towards the modification of gluten proteins to improve technological features and functionality. In breadmaking, when weak Hour (low protein content) is used or general stabilization is desired for technological purposes, additives can be used to stabilize the gluten protein matrix. The use of transglutaminase (TG) has grown in popularity as they promote specific cross-linking between residues of glutamine and lysine in proteins. Another way of improving dough functionality is by increasing the oxidation of disulfide groups by adding gluten which is a co-product of the starch industry. Industrial production of gluten includes the use of heating and shear forces, which may impact gluten dough-forming ability. Thus, increased understanding of the interplay of gluten processing and the impact of choice of the TG origin in gluten dough quality is highly applicable in food industry.

  • 265.
    Cerrato, C. P.
    et al.
    Department of Microbiology, Tumor and Cancer Biology, Karolinska Institutet, Stockholm, Sweden.
    Kivijärvi, Tove
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Langel, Ü.
    Department of Biochemistry and Biophysics, the Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden Laboratory of Molecular Biotechnology, Institute of Technology, University of Tartu, Tartu, Estonia.
    Mitochondrial Targeting Probes, Drug Conjugates, and Gene Therapeutics2022In: Cell Penetrating Peptides, Springer Nature , 2022, p. 429-446Chapter in book (Refereed)
    Abstract [en]

    Mitochondria represent an important drug target for many phatology, including neurodegeneration, metabolic disease, heart failure, ischemia-reperfusion injury, and cancer. Mitochondrial dysfunctions are caused by mutation in mitochondrial DNA or in nuclear genes encoding mitochondrial proteins. Cell-penetrating peptides (CPPs) have been employed to overcome biological barriers, target this organelle, and therapeuticaly restore mitochondrial functions. Here, we describe recent methods used to deliver oligonucleotides targeting mitochondrial protein by using mitochondrial penetrating peptides. In particular, we highlight recent advances of formulated peptides/oligonucleotides nanocomplexes as a proof-of-principle for pharmaceutical form of peptide-based therapeutics.

  • 266.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, Svante Arrhenius Vag 16B, SE-10691 Stockholm, Sweden..
    Kivijärvi, Tove
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Tozzi, Roberta
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, Svante Arrhenius Vag 16B, SE-10691 Stockholm, Sweden..
    Lehto, Tonis
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, Svante Arrhenius Vag 16B, SE-10691 Stockholm, Sweden..
    Gestin, Maxime
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, Svante Arrhenius Vag 16B, SE-10691 Stockholm, Sweden..
    Langel, Ulo
    Stockholm Univ, Dept Biochem & Biophys, Arrhenius Labs Nat Sci, Svante Arrhenius Vag 16B, SE-10691 Stockholm, Sweden.;Univ Tartu, Lab Mol Biotechnol, Inst Technol, Nooruse 1, EE-50411 Tartu, Estonia..
    Intracellular delivery of therapeutic antisense oligonucleotides targeting mRNA coding mitochondrial proteins by cell-penetrating peptides2020In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 8, no 47, p. 10825-10836Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides are a promising therapeutic strategy for a wide variety of degenerative diseases, ageing, and cancer. Among the multitude of cell-penetrating peptides, PepFect14 has been preferentially used in our laboratory for oligonucleotide delivery into cells and in vivo mouse models. However, this activity has mainly been reported towards cytoplasm and nuclei, while the mentioned disorders have been linked to mitochondrial defects. Here, we report a library generated from a combinatorial covalent fusion of a mitochondrial-penetrating peptide, mtCPP1, and PepFect14 in order to deliver therapeutic biomolecules to influence mitochondrial protein expression. The non-covalent complexation of these peptides with oligonucleotides resulted in nano-complexes affecting biological functions in the cytoplasm and on mitochondria. This delivery system proved to efficiently target mitochondrial genes, providing a framework for the development of mitochondrial peptide-based oligonucleotide technologies with the potential to be used as a treatment for patients with mitochondrial disorders.

  • 267.
    Ceylan, Aylin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Synthesis of thermally reversible crosslinked carboxymethyl cellulose2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The challenges related to the usage and handling of plastic materials in the current society include issues connected to recycling and the non-renewable feedstock. In an attempt to meet these challenges, the use of cellulose-based materials as well as developing easier recycling routes can play an important role.

    This thesis main aim was to synthesize a thermally reversible crosslinked material based on the cellulose derivative carboxymethyl cellulose (CMC), through the Diels-Alder reaction. This was achieved through grafting the CMC with furfurylamine, synthesizing a bismaleimide crosslinker, and crosslinking of these thermally through the maleimide-furan coupling. 

    The grafting reaction as well as the crosslinker synthesis were both successfully produced and confirmed through NMR, FTIR, MALDI, XRD, and SEM analysis. These compounds were crosslinked thermally into a thermoset through the Diels-Alder reaction and the crosslinking could be partly reversed through the retro reaction. A green character was implemented through the introduction of more environmentally friendly solvents. Further optimization of the crosslinking reaction will be necessary.

    The use of cellulose-based polymers and thermoreversible crosslinking via the Diels-Alder reaction, could be a step towards materials belonging in a sustainable circular material management system.

  • 268.
    Chandel, Anshu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Development of biobased lubricant component from brown algae alginate derivatives2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Research in bio-based products in the field of polymer chemistry is vital to reduce and replace the status quo of fossil-based products. Base oils, which are the main component in lubricant products are vastly based on crude oil. Due to the increased pressure from consumers and regulators to reduce crude oil dependencies, biobased alternatives are in demand. The aim of the thesis is to evaluate the development potential of bio-based additive components from alginates to be used as a component in base oils. Alginate is a type of polysaccharide derived from brown seaweed, which is a biobased resource obtained from algae farming and refining process. Currently, alginates are widely used as a thickening, gelling, emulsifying or stabilizing agent to achieve smooth and creamy textures in processed food products without separation of ingredients (e.g., ice-cream, yoghurt, various bakery products etc). Research in alginate-based hydrogels is being adapted for various biomedical application such as drug delivery technology. Therefore, the objective of the thesis was to develop a biobased additive from alginate feedstock via chemical modifications. Alginates were depolymerized and modified to increase hydrophobicity followed by solubility tests in different base oils. If successful solubility in a base oil is achieved, additive effects such as oxidation stability and rheology was to be evaluated at Nynas AB in accordance with the lubricant testing standards. 

    Hydrophobic modification on carboxyl group of alginates was investigated by grafting different lengths of alkyl chains. Modified alginate samples with butyl, hexyl, decyl, pentadecyl and stearyl chains were grafted via an ester bond on the carboxyl group of alginates via a two-step synthesis scheme. The first synthesis step was to convert from sodium alginate or alginic acid to tetrabutylammonium (TBA) alginate, where degradation of alginates under heat and alkaline conditions was observed with aqueous-organic size-exclusion chromatography. The second step was to graft different lengths alkyl chains on TBA-alginate via SN2 substitution mechanism with respective alkyl bromides. The substitution reaction was successfully conducted in dimethyl sulfoxide solvent with tetrabutyl ammonium fluoride trihydrate dissolution promoter to dissolve TBA-alginate. 

    Hydrophobic modification on both hydroxyl and carboxyl groups on alginate was investigated by converting the hydroxyl group followed by aforementioned carboxyl group modification scheme. The hydroxyl group was reacted with tetradecyl-dodecyl glycidyl ether (DGE) via epoxide ring opening reaction under heat and alkaline conditions. The reaction was conducted in aqueous phase with the presence of sodium dodecyl sulphate surfactant to improve reaction efficiency. The hydroxyl modified alginate product was further modified by grafting decyl chain via the aforementioned carboxyl modification scheme. 

    Finally, hydrophobic modification on acid hydrolysed alginate was performed to investigate solubility of low molecular weight modified alginate in base oils. Acid hydrolysis of alginate was conducted in acidic aqueous medium with heat reflux setup. The acid hydrolysed alginate was grafted with decyl chain via aforementioned carboxyl modification protocol. 

    The products obtained from each synthesis steps in different types of hydrophobic modifications were characterised with 1H-NMR and FT-IR spectroscopy. All hydrophobically modified alginate products were tested and observed to be insoluble in rapeseed, estolide, 2-ethylhexyl laurate and naphthenic base oils. Thus, 2% (w/w) modified alginates mixed in grease were evaluated by the means of high pressure-differential scanning calorimeter (HP-DSC) for oxidation stability. The oxidation stability decreased with the presence of tetrabutyl ammonium (TBA) ions and ether bonds in hydroxyl modified TBA-alginate and fully (dodecyl-decyl) grafted alginate respectively. Alkyl grafted alginates had no significant impact on oxidation stability in comparison to pure grease, indicating good oxidation stability of ester bonds.

  • 269. Chang, B.
    et al.
    Schneider, K.
    Patil, N.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY, Hamburg, Germany.
    Heinrich, G.
    Microstructure characterization in a single isotactic polypropylene spherulite by synchrotron microfocus wide angle X-ray scattering2018In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 142, p. 387-393Article in journal (Refereed)
    Abstract [en]

    Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75° with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%–56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 °C and it decreases to 0.11 as the crystallization temperature is decreased to 130 °C. The b-axis and c-axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a-axis prefers to align in the radius direction.

  • 270.
    Chang, Tingru
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden; Department of Neuroscience, Karolinska Institutet, Stockholm, SE-171 77, Sweden.
    Butina, Karen
    Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;KTH Royal Inst Technol, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, SE-17177 Stockholm, Sweden..
    Herting, Gunilla
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rajarao, Gunaratna Kuttuva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Richter-Dahlfors, Agneta
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden; Karolinska Inst, Dept Neurosci, SE-17177 Stockholm, Sweden.
    Blomberg, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;KTH Royal Inst Technol, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, SE-17177 Stockholm, Sweden..
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    The interplay between atmospheric corrosion and antimicrobial efficiency of Cu and Cu5Zn5Al1Sn during simulated high-touch conditions2021In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 185, article id 109433Article in journal (Refereed)
    Abstract [en]

    The interplay between atmospheric corrosion and antimicrobial efficiency of bare Cu and Cu5Zn5Al1Sn was studied upon exposures simulating high-touch surface conditions. The survival of the bacteria Bacillus subtilis during surface contact with Cu and Cu5Zn5Al1Sn was examined under different degrees of surface oxidation, tarnishing, wettability and copper ion release. Depending on surface conditions complete bacteria inhibition was obtained within 4 min on Cu and within 6-10 min on Cu5Zn5Al1Sn. The antibacterial efficiency increases slightly with copper release rate and is governed by complex interactions between the corroded metal surface, bacteria and extracellular polymeric substances produced by the bacteria.

  • 271.
    Chang, Tingru
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH, Centres, Center for the Advancement of Integrated Medical and Engineering Sciences, AIMES. Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
    Leygraf, Christopher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Herting, Gunilla
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Fan, Yanmiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Babu, Prasath
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Malkoch, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Blomberg, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Center for the Advancement of Integrated Medical and Engineering Sciences, AIMES. Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
    Effect of blue light illumination on atmospheric corrosion and bacterial adhesion on copper2024In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 230, article id 111909Article in journal (Refereed)
    Abstract [en]

    The effect of blue light on atmospheric corrosion of Cu and on the antimicrobial properties was explored upon exposure mimicking the condition of hygienic surface disinfection. The results show that blue light illumination enhanced the formation of Cu2O, resulting in a slightly increased corrosion resistance of Cu without pre-deposited NaCl, whereas the enhanced formation of Cu2O, CuCl and/or Cu(OH)3Cl on copper with pre-deposited NaCl caused concomitant corrosion product flaking and a reduced corrosion resistance. The blue light induced enhancement of Cu corrosion led to increased surface roughness and more pronounced integration of bacteria within the corrosion products.

  • 272.
    Chang, Tingru
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;KTH Royal Inst Technol, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, Stockholm, Sweden..
    Sepati, M.
    Politecn Milan, Dept Chem Mat & Chem Engn Giulio Natta, Milan, Italy..
    Herting, Gunilla
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christopher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rajarao, Gunaratna Kuttuva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Butina, K.
    Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, Stockholm, Sweden..
    Richter-Dahlfors, Agneta
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, Stockholm, Sweden..
    Blomberg, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Karolinska Inst, AIMES Ctr Adv Integrated Med & Engn Sci, Stockholm, Sweden.;KTH Royal Inst Technol, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, Stockholm, Sweden..
    A novel methodology to study antimicrobial properties of high-touch surfaces used for indoor hygiene applications-A study on Cu metal2021In: PLOS ONE, E-ISSN 1932-6203, Vol. 16, no 2, article id e0247081Article in journal (Refereed)
    Abstract [en]

    Metal-based high-touch surfaces used for indoor applications such as doorknobs, light switches, handles and desks need to remain their antimicrobial properties even when tarnished or degraded. A novel laboratory methodology of relevance for indoor atmospheric conditions and fingerprint contact has therefore been elaborated for combined studies of both tarnishing/corrosion and antimicrobial properties of such high-touch surfaces. Cu metal was used as a benchmark material. The protocol includes pre-tarnishing/corrosion of the high touch surface for different time periods in a climatic chamber at repeated dry/wet conditions and artificial sweat deposition followed by the introduction of bacteria onto the surfaces via artificial sweat droplets. This methodology provides a more realistic and reproducible approach compared with other reported procedures to determine the antimicrobial efficiency of high-touch surfaces. It provides further a possibility to link the antimicrobial characteristics to physical and chemical properties such as surface composition, chemical reactivity, tarnishing/corrosion, surface roughness and surface wettability. The results elucidate that bacteria interactions as well as differences in extent of tarnishing can alter the physical properties (e.g. surface wettability, surface roughness) as well as the extent of metal release. The results clearly elucidate the importance to consider changes in chemical and physical properties of indoor hygiene surfaces when assessing their antimicrobial properties.

  • 273.
    Chen, Bin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Coppieters, S.
    Department of Materials Engineering, KU Leuven, Ghent Campus, Gebroeders De Smetstraat 1, 9000, Ghent, Belgium, Ghent Campus, Gebroeders De Smetstraat 1.
    Meshfree Digital Image Correlation Using Element Free Galerkin Method: Theory, Algorithm and Validation2023In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 63, no 3, p. 517-528Article in journal (Refereed)
    Abstract [en]

    Background: The association of advanced digital image correlation (DIC) and numerical simulation has been widely used for inverse parameter identification. Objective: It is attractive to develop an accurate DIC method sharing the common features with numerical simulation, which can lead to better synergy between experiments and simulations. Methods: A new meshfree digital image correlation (MF-DIC) using element free Galerkin method (EFGM) is proposed for deformation measurement. The EFGM is a classical meshfree method in numerical studies, and it is directly used to construct the shape function in MF-DIC from a set of scattered nodes for image matching. The MF-DIC is principally different from the classical local DIC and global DIC since it does not rely on the concept of a subset or an element. Results: In MF-DIC, the C1-continuous displacement for every point is constructed based on a group of scattered nodes in a small support domain surrounding it. The continuous strain map can then be directly derived from the displacement, instead of using an additional smoothing technique as required in classical local DIC or post-processing used in global DIC. A performance assessment based on the Metrological Efficiency Indicator (MEI), as defined in DIC Challenge 2.0, shows that the proposed MF-DIC yields an excellent balance between spatial resolution and measurement resolution for both displacement and strain measurements. Conclusions: Given that the proposed MF-DIC shares common features with the classical meshfree method in computational mechanics, it paves the way for an enhanced synergy between experiments and simulations required for robust inverse parameter identification methods.

  • 274.
    Chen, Bin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Coppieters, Sam
    Department of Materials Engineering, KU Leuven, Ghent Technology Campus, Gebroeders De Smetstraat 1, 9000 Ghent, Belgium.
    Jungstedt, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Element-removal global digital image correlation for accurate discontinuous deformation field measurement in fracture mechanics2023In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 290, article id 109493Article in journal (Refereed)
    Abstract [en]

    We propose an element-removal (ER) global digital image correlation (DIC) method to improve the measurement accuracy of discontinuous deformation fields, such as crack propagation. The occurrence of cracks in materials or structures inevitably deteriorates the tracking accuracy, and, consequently, the strain field accuracy obtained by regular subset and global DIC. The proposed ER-global-DIC algorithm iteratively identifies and removes all the elements covering the crack, during the updating of displacement fields. In the remaining elements, the continuous shape function is applicable for accurate deformation measurement. In principle, although elements that contain the cracks are removed, the algorithm preserves the same number of nodes since the nodes are retained by the remaining elements. Synthetically deformed images based on analytical discontinuous displacement fields validate the effectiveness and accuracy of the proposed method. The ER-global-DIC is further applied to measure the discontinuous displacement fields containing a crack deflection, generated from a finite element model with a cohesive zone model. The results demonstrate the potential of the proposed method for discontinuous deformation measurement on advanced materials, e.g., fiber-reinforced composites.

  • 275.
    Chen, Bin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Jungstedt, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fast and large-converge-radius inverse compositional Levenberg-Marquardt algorithm for digital image correlation: principle, validation, and open-source toolbox2022In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 151, article id 106930Article in journal (Refereed)
    Abstract [en]

    This paper presents an inverse compositional Levenberg-Marquardt (IC-LM) algorithm for robust, efficient, and accurate image registration in digital image correlation (DIC). In essence, the IC-LM algorithm is a mixture of the classical inverse compositional Gaussian-Newton (IC-GN) and gradient descent algorithms. Further normalization of the local coordinate and image intensity is also introduced to adaptively initialize the damping parameter in the IC-LM algorithm. The proposed IC-LM algorithm is proven to hold a larger converge radius while having comparable accuracy, precision, and efficiency compared with the classical IC-GN algorithm. The efficient reliability-guided displacement tracking strategy is also merged into the IC-LM algorithm to provide an accurate initial guess for all calculation points. For the sake of reproducibility of this algorithm, the open-source MATLAB toolbox featuring the IC-LM algorithm is available on GitHub ( https://github.com/cbbuaa/DIC _ ICLM _ MATLAB ).

  • 276.
    Chen, Bin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Montanari, Celine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    A distortion-map-based method for morphology generation in multi-phase materials - application to wood2023In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 244, article id 110262Article in journal (Refereed)
    Abstract [en]

    Increased use of multi-phase, wood-based biocomposites may contribute to sustainable development. The porous microstructure offers unique possibilities for modification, but global properties are often predicted based on simplified unit cells and homogenization. For materials design, simulations based on complex 3D microstructures with statistical variability are alternatives to better understanding physical properties. Parametric models are developed in a distortion-map-based method to represent 3D wood microstructures. Basic structures of uniform tubular cells and other features are generated followed by distortion mapping. These maps are highly adaptable and can generate realistic features and variability. Fibers, vessels, and ray cells are realistically distributed. The models are realistic, versatile, and scalable, as well as can be used to simulate the mechanical, optical, and hydrodynamic properties of complex composites. The model is promising for generating large sets of data to train deep learning networks for multi-physics research.

  • 277. Chen, C.
    et al.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Burgert, I.
    Hu, L.
    Wood Nanomaterials and Nanotechnologies2021In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 33, no 28, article id 2006207Article in journal (Refereed)
  • 278. Chen, C.
    et al.
    Kuang, Y.
    Zhu, S.
    Burgert, I.
    Keplinger, T.
    Gong, A.
    Li, T.
    Berglund, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Eichhorn, S. J.
    Hu, L.
    Structure-property-function relationships of natural and engineered wood2020In: Nature Reviews Materials, ISSN 2058-8437, Vol. 5, no 9, p. 642-666Article in journal (Refereed)
    Abstract [en]

    The porous hierarchical structure and anisotropy of wood make it a strong candidate for the design of materials with various functions, including load bearing, multiscale mass transport, and optical and thermal management. In this Review, the composition, structure, characterization methods, modification strategies, properties and applications of natural and modified wood are discussed.

    The complex structure of wood, one of the most abundant biomaterials on Earth, has been optimized over 270 million years of tree evolution. This optimization has led to the highly efficient water and nutrient transport, mechanical stability and durability of wood. The unique material structure and pronounced anisotropy of wood endows it with an array of remarkable properties, yielding opportunities for the design of functional materials. In this Review, we provide a materials and structural perspective on how wood can be redesigned via structural engineering, chemical and/or thermal modification to alter its mechanical, fluidic, ionic, optical and thermal properties. These modifications enable a diverse range of applications, including the development of high-performance structural materials, energy storage and conversion, environmental remediation, nanoionics, nanofluidics, and light and thermal management. We also highlight advanced characterization and computational-simulation approaches for understanding the structure-property-function relationships of natural and modified wood, as well as informing bio-inspired synthetic designs. In addition, we provide our perspective on the future directions of wood research and the challenges and opportunities for industrialization.

  • 279.
    Chen, Chao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Bactericidal Surfaces Prepared by Femtosecond Laser Patterning and Layer-by-Layer Polyelectrolyte CoatingManuscript (preprint) (Other academic)
    Abstract [en]

    Antimicrobial surfaces are important in medical, clinical, and industrial applications, where bacterial infection and biofouling may constitute a serious threat to human health. Conventional approaches against bacteria involve coating the surface with antibiotics, cytotoxic polymers, or metal particles. However, these types of functionalization have a limited life-time and pose concerns in terms of leaching and degradation of the coating. Thus, there is a great interest in developing long-lasting and non-leaching bactericidal surfaces. To obtain a bactericidal surface, we combine μm-scale patterning of borosilicate glass surfaces by ultrashort pulsed laser irradiation and a non-leaching layer-by-layer polyelectrolyte modification of the surface. The combination of surface structure and surface charge results in an enhanced bactericidal effect against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The laser patterning and the layer-by-layer modification are environmentally friendly processes that are applicable to a wide variety of materials, which makes this method uniquely suited for fundamental studies of bacteria-surface interactions and paves the way for its applications in a variety of fields, such as in hygiene products and medical devices.

    Download (pdf)
    spikblad
  • 280.
    Chen, Chao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Development of Non-leaching Antibacterial Approaches on Cellulose-based Substrates and Their Mechanisms2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The layer-by-layer (LbL) technique is becoming a powerful tool that has been applied in many surface coatings and functionalizations in recent years. It has many advantages including a fast and mild process, the flexibility of choice of substrate, and the easiness to scale-up. Novel antibacterial materials can be achieved using this technique, by immobilizing selected antibacterial agents on surfaces of desired substrates. An ideal antibacterial agent, a cationic polyelectrolyte, can be LbL-deposited onto the surfaces in mono or multi layers, make the surfaces lethal to the bacteria due to their positive charge. This approach is able not only to effectively control the spreading of bacteria but also to minimize bacterial resistance as well as the environmental impact.

    Cellulose fibres modified by different cationic polyelectrolytes including PDADMAC, PAH, PVAm as either monolayer or multilayer assembled with PAA using LbL deposition have shown more than 99.99 % bacterial removal as well as the inhibition of bacterial growth. Among these modifications, two layers of PVAm assembled with one layer of PAA have shown the highest antibacterial efficiency due to the highest adsorbed amount and charge density. Secondly, PAA was replaced by a bio-based cellulose nano-fibril (CNF), as a middle layer between two layers of PVAm, which decreases the carbon-footprint and expands the possibility of using LbL technique in antibacterial applications, since the LbL technique can be used long as the alternate layers are oppositely charged. The fibres modified with this approach have shown similar and even better antibacterial properties than those of PAA.

    To develop the antibacterial approach using LbL on cellulose fibres, it is also essential to understand the antibacterial mechanism. It was found that the charge density and surface structures are two important factors affecting bacterial adhesion and the bactericidal effect. To study this, different charged cellulose model surfaces were made by coating oxidized, regenerated cellulose followed by PVAm/CNF/PVAm LbL deposition, and a better antibacterial effect was observed on the higher charged surface. By calculating the force between the bacteria and charged surface, it was suggested that a higher interaction due to the higher surface charge causes a large stress on the bacterial cell wall which leads to the disruption of the bacteria. To further improve the bactericidal effect, the flat surfaces were patterned with micro and nano structures using a femtosecond laser technique. The weakening of the bacterial cell wall caused by the charged surface makes the bacteria more vulnerable and easier to disrupt. This approach has been shown to be valid on both Gram-positive S. aureus, and Gram-negative E. coli. The effect was greater on E. coli with a weaker membrane structure and higher surface potential, which shows that the antibacterial mechanism is a physical disrupt of the bacterial cell.

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    Development of Non-leaching Antibacterial Approaches on Cellulose-based Substrates and Their Mechanisms
  • 281.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Antibacterial evaluation of CNF/PVAm multilayer modified cellulose fiber and cellulose model surface2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 385-396Article in journal (Refereed)
    Abstract [en]

    Earlier studies have shown that 3-layer-modified cellulose fibers with poly(acrylic acid) (PAA) as the middle layer between two cationic polyelectrolyte polyvinylamine (PVAm) layers have strong antibacterial efficacy in terms of both bacteria adsorption and bacterial growth inhibition. In the present work, the fossil-based PAA middle layer was replaced by sustainable wood-based cellulose nano-fibrils (CNF), i. e., the fibers were modified by a 3-layer PVAm/CNF/PVAm system. Interestingly, the antibacterial efficacy of this system was greater than that of the previous PVAm/PAA/PVAm system. A higher salt concentration and lower assembly pH in the multilayer build-up resulted in better bacterial reduction. As the surface of a cellulose fiber is heterogeneous, making it difficult to characterize and visualize at high resolution, more homogeneous cellulose model surfaces were prepared by spin coating the dissolved cellulose fiber onto a silica surface to model the fiber surface. With increasing ionic strength, more aggregated and heterogeneous structures can be observed on the PVAm/CNF/PVAm modified model surfaces. The adsorbed bacteria distributed on the structured surfaces were clearly seen under fluorescence microscopy. Adsorbed amounts of bacteria on either aggregate or flat regions were quantified by scanning electron microscopy (SEM). More adsorbed bacteria were clearly seen on aggregates than on the flat regions at the surfaces. Degrees of bacteria deformation and cell damage were also seen under SEM. The surface roughness of the modified model surfaces was examined by atomic force microscopy (AFM), and a positive correlation was found between the surface roughness and the bacterial adhesion. Thus, an additional factor that controls adhesion, in addition to the surface charge, which is probably the most dominant factor affecting the bacteria adhesion, is the surface structures, such as roughness. 

  • 282.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enrico, Alessandro
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Herland, Anna
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems. Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institute, Stockholm, 17177, Sweden.
    Niklaus, Frank
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Bactericidal surfaces prepared by femtosecond laser patterning andlayer-by-layer polyelectrolyte coating2020In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 575, p. 286-297Article in journal (Refereed)
    Abstract [en]

    Antimicrobial surfaces are important in medical, clinical, and industrial applications, where bacterial infection and biofouling may constitute a serious threat to human health. Conventional approaches against bacteria involve coating the surface with antibiotics, cytotoxic polymers, or metal particles. However, these types of functionalization have a limited lifetime and pose concerns in terms of leaching and degradation of the coating. Thus, there is a great interest in developing long-lasting and non-leaching bactericidal surfaces. To obtain a bactericidal surface, we combine micro and nanoscale patterning of borosilicate glass surfaces by ultrashort pulsed laser irradiation and a non-leaching layer-by-layer polyelectrolyte modification of the surface. The combination of surface structure and surface charge results in an enhanced bactericidal effect against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The laser patterning and the layer-by-layer modification are environmentally friendly processes that are applicable to a wide variety of materials, which makes this method uniquely suited for fundamental studies of bacteria-surface interactions and paves the way for its applications in a variety of fields, such as in hygiene products and medical devices.

  • 283.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, p. 649-658Article in journal (Refereed)
    Abstract [en]

    Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

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  • 284.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Cheng, G.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Mathematical modelling of molten alloy mixing in a continuous casting tundish - A hydrodynamic study2015In: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, p. 407-411Conference paper (Refereed)
    Abstract [en]

    The emergence of the nozzle clogging have inspired steelmakers to optimize the alloying routine from alloying in ladle to alloying in tundish or in continuous casting mould. Meanwhile, wire injection in tundish has been shown to be successful for postalloying and tundish temperature adjustment. However, there is limited information on the continuous feeding of alloy in tundishes. There are three aspects to be considered: a) "alloy melting", b) "alloy particle dispersion" and c) "liquid alloy mixing". In the present paper, the "liquid alloy mixing" process is studied using CFD (Computational Fluid Dynamics) from a hydrodynamic perspective. In the simulation, the molten alloy is described by the density coupled mixed composition fluid model, which has been verified and validated by water modelling experiments using black ink and KCl tracer mixing in water as a priori. In the present model, the density of the liquid alloy is assumed to be 1.15 or 0.85 times of that of the liquid steel. Thereafter, the denser alloy injection at two positions has been studied, i.e. near the inlet (L1) and at the centre of the tundish (L2). The results indicate that the breakthrough time for the mass fraction of alloy at the outlet are about 100s for both locations. The difference is when the alloy was injected at the center (L2), there is a bypassing flow above the dam. As a result, the mass fraction of alloy at the outlet increases rapidly but the homogeneity in the tundish bath is reduced. Moreover, the denser alloy injection with different velocities was studied. The result shows that the mixing is slightly enhanced during the initial injection stage for the big velocity case. Besides, a test simulation on the mixing of a lighter alloy indicates that the alloy is floating to the top surface.

  • 285.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Influence of Cellulose Charge on Bacteria Adhesion and Viability to PVAm/CNF/PVAm-Modified Cellulose Model Surfaces2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    A contact-active antibacterial approach based on the physical adsorption of a cationic polyelectrolyte onto the surface of a cellulose material is today regarded as an environment-friendly way of creating antibacterial surfaces and materials. In this approach, the electrostatic charge of the treated surfaces is considered to be an important factor for the level of bacteria adsorption and deactivation/killing of the bacteria. In order to clarify the influence of surface charge density of the cellulose on bacteria adsorption as well as on their viability, bacteria were adsorbed onto cellulose model surfaces, which were modified by physically adsorbed cationic polyelectrolytes to create surfaces with different positive charge densities. The surface charge was altered by the layer-by-layer (LbL) assembly of cationic polyvinylamine (PVAm)/anionic cellulose nanofibril/PVAm onto the initially differently charged cellulose model surfaces. After exposing the LbL-treated surfaces to Escherichia coli in aqueous media, a positive correlation was found between the adsorption of bacteria as well as the ratio of nonviable/viable bacteria and the surface charge of the LbL-modified cellulose. By careful colloidal probe atomic force microscopy measurements, it was estimated, due to the difference in surface charges, that interaction forces at least 50 nN between the treated surfaces and a bacterium could be achieved for the surfaces with the highest surface charge, and it is suggested that these considerable interaction forces are sufficient to disrupt the bacterial cell wall and hence kill the bacteria.

  • 286.
    Chen, Danjing
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Polymer-based additive manufacturing: optimization for high-performance degradable polymers2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project, we develop a reproducible polymerization method to achieve stable production of poly(ε-caprolactone-co-p-dioxanone) (PCLDX), scale-up the filament fabrication to produce 1.75 mm filaments and optimize 3D printing process to manufacture scaffolds/devices for soft tissue engineering.

    PCLDX, with a higher degradation rate and better pliability compared to poly(ε-caprolactone) (PCL), was successfully synthesized by reproducible copolymerization of ε-caprolactone (CL) and p-dioxanone (DX). The synthesized PCLDX exhibited a polymer composition of 85 mol% CL : 15 mol% DX, molar mass around 40 kg∙mol-1, dispersity around 1.8, and relatively low melting point around 45 ℃.

    From PCLDX particles to final scaffolds, two processes, including filament fabrication and scaffold manufacturing, were designed and optimized. For the filament fabrication process, low extrusion temperature (65 and 80 ℃) and low extrusion speed (100 cm∙min-1) were applied to save energy and minimize degradation. PCLDX filaments with an even diameter of 1.75 mm were fabricated using suitable particle sizes (diameter of 3-4 mm) and a cooling method (mixture of water and dry ice, 0℃). The obtained filaments exhibited lower young’s modulus (25% lower than PCL), consistent thermal properties, good surface quality, and printability. The thermal degradation of PCLDX during the process was negligible, and the molar mass was kept almost unchanged. The process has been scaled up to produce high amounts of PCLDX filaments, whose productivity rate reached up to 140 g∙h-1.

    For the scaffold manufacturing process, porous scaffolds were manufactured by feeding manually and printing slowly (5 mm/s). The printability was assessed and validated using produced PCL/PCLDX filaments and commercial PCL filaments. The optimized printing protocol maintained the molar mass and dispersity of the material. The produced scaffolds possessed consistent thermal properties independent on polymer batches and good surface quality. The optimized printing protocol was also successfully applied to print complicated prototypes, such as meniscus and knee prosthesis for potential biomedical applications.

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  • 287.
    Chen, Guo-Qiang
    et al.
    Tsinghua Univ, CSSB, Sch Life Sci, Beijing 100084, Peoples R China..
    Albertsson, Ann-Christine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Polyhydroxyalkanoates and Other Biopolymers2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 9, p. 3211-3212Article in journal (Other academic)
  • 288.
    Chen, Hui
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Light Scattering Effects in Transparent Wood Biocomposites2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transparent wood (TW) shows interesting optical properties and offers a sustainable alternative to petroleum-based polymer glasses. The influence of the TW internal structure (e.g. fiber alignment, volume fraction of cellulose, lignin content, defects from preparation process) on the optical properties is poorly understood, which limits its use in various applications. It is also true for transparent cellulose biocomposites in general. In this thesis, eco-friendly TW biocomposites are investigated. The work focuses on experimental characterization, structure-optical property relationships and possibilities to quantify such relationships.  

                    TWs made of delignified wood substrates with longitudinal direction of the tree parallel to the specimen surface are prepared. Relationships between anisotropic scattering and fiber alignment are studied by scattering angle measurement. Anisotropic photons distributions are compared between two fiber directions and various sample thicknesses. Next, attenuation coefficients (related to the anisotropic diffusion coefficients and absorption coefficient) for TWs are obtained by combining the photon diffusion equation with total transmittance measurements. The results indicate strong influence from the air gaps between wood substrate phase and polymer in the lumen pores on the scattering. Beside the airgaps between wood substrate and polymer, refractive index mismatch between polymer and wood substrate strongly influences the scattering. Thus, immersion liquid method (based on the total transmittance measurement) combined with a light transmission model (based on Fresnel reflection theory) is applied to estimate the refractive index of the delignified wood substrate. This facilitates TW design (i.e. the proper polymer selection for various applications) and modelling of the optical properties of delignified wood based transparent materials. Finally, extinction coefficients, Rayleigh scattering and absorption coefficients of TW are extracted from photon budget measurements combined with a light diffusion model developed. With higher volume fraction of cellulose, all these parameters are increased, although polymer-cellulose refractive index mismatch is the dominating factor controlling transmittance. The strong forward scattering in TW is analysed, and Rayleigh scattering has a strong effect on haze. The influence of lignin content on the absorption coefficient is also discussed.

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  • 289.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Baitenov, Adil
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yan, Max
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

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  • 290.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Montanari, Celine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Shanker, Ravi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Marcinkevičius, Saulius
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Photon Walk in Transparent Wood: Scattering and Absorption in Hierarchically Structured Materials2022In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, article id 2102732Article in journal (Refereed)
    Abstract [en]

    The optical response of hierarchical materials is convoluted, which hinders their direct study and property control. Transparent wood (TW) is an emerging biocomposite in this category, which adds optical function to the structural properties of wood. Nano- and microscale inhomogeneities in composition, structure and at interfaces strongly affect light transmission and haze. While interface manipulation can tailor TW properties, the realization of optically clear wood requires detailed understanding of light-TW interaction mechanisms. Here we show how material scattering and absorption coefficients can be extracted from a combination of experimental spectroscopic measurements and a photon diffusion model. Contributions from different length scales can thus be deciphered and quantified. It is shown that forward scattering dominates haze in TW, primarily caused by refractive index mismatch between the wood substrate and the polymer phase. Rayleigh scattering from the wood cell wall and absorption from residual lignin have minor effects on transmittance, but the former affects haze. Results provide guidance for material design of transparent hierarchical composites towards desired optical functionality; we demonstrate experimentally how transmittance and haze of TW can be controlled over a broad range.

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  • 291.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Montanari, Celine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Yan, Max
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Refractive index of delignified wood for transparent biocomposites2020In: RSC Advances, E-ISSN 2046-2069, Vol. 10, p. 40719-40724Article in journal (Refereed)
    Abstract [en]

    Refractive index (RI) determination for delignified wood templates is vital for transparent wood composite fabrication. Reported RIs in the literature are based on either single plant fibers or wood powder, measured by the immersion liquid method (ILM) combined with mathematical fitting. However, wood structure complexity and the physical background of the fitting were not considered. In this work, RIs of delignified wood templates were measured by the ILM combined with a light transmission model developed from the Fresnel reflection/refraction theory for composite materials. The RIs of delignified balsa wood are 1.536 ± 0.006 and 1.525 ± 0.008 at the wavelength of 589 nm for light propagating perpendicular and parallel to the wood fiber direction, respectively. For delignified birch wood, corresponding values are 1.537 ± 0.005 and 1.529 ± 0.006, respectively. The RI data for delignified wood scaffolds are important for tailoring optical properties of transparent wood biocomposites, and also vital in optical properties investigations by theoretical modelling of complex light propagation in transparent wood and related composites. The developed light transmission model in combination with the immersion liquid method can be used to determine the RI of complex porous or layered solid materials and composites.

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  • 292.
    Chen, Kaixuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. School of Material Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China.
    Zhang, Jiawei
    School of Material Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China.
    Chen, Xiaohua
    State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, People’s Republic of China.
    Wang, Zidong
    School of Material Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China.
    Effects of solute content on microstructure of nano precipitate-fine grain synergistically reinforced copper alloys2020In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847Article in journal (Refereed)
    Abstract [en]

    Alloying of Fe, Co was reported to tailor microstructure of copper alloys into a nanoprecipitate-fine grain (NPFG) structure, i.e. nano-sized iron-rich precipitates dispersed inside refined grains. Here, we investigate the solute effect of Sn, Zn on NPFG structure in as-cast copper samples. Mechanisms are proposed to account for the solute effect on precipitate and grain features. Solutes restrict coarsening but facilitate undesirable morphology transition from spherical to angular of iron-rich precipitates. Meantime, solutes allow more precipitates to be active in the nucleation of copper and consequently induce finer grains. Minor Sn is added to optimise NPFG structure and leads to an excellent strength–ductility combination in Cu–1.5Fe–0.1Sn (wt-%) alloy. This work provides a solute-alloying strategy to achieve desired mechanical properties in metals.

  • 293.
    Chen, Lan
    et al.
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Wei, Xiaoxiao
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Wang, Huan
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Yao, Min
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Zhang, Liming
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Gellerstedt, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wang, Shuangfei
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    Min, Douyong
    Guangxi Univ, Coll Light Ind & Food Engn, Nanning 530004, Peoples R China.;Guangxi Univ, Guangxi Key Lab Clean Pulp & Papermaking & Pollut, Nanning 530004, Peoples R China..
    A modified ionization difference UV-vis method for fast quantitation of guaiacyl-type phenolic hydroxyl groups in lignin2022In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 201, p. 330-337Article in journal (Refereed)
    Abstract [en]

    An ionization difference UV-Vis method (Delta epsilon-spectrum method) is the most potentially simple method for fast quantitation of phenolic hydroxyl groups (ph-OH) in lignin. However, the underestimated results were calculated from the conventional Delta epsilon-spectrum method using one- or two-point wavelengths measurement. In this study, a modified Delta epsilon-spectrum method using multi-point wavelengths measurement was developed and the negative absorbance was also considered. Four main typical lignin models, e.g. vanilla alcohol, 5-5 biphenyl, stilbenoid and vanillin, were applied as the guaiacyl-type (G-type) phenolic models for the determination of ph-OH by the modified Delta epsilon-spectrum method. The 2-methoxyethanol/water/acetic acid = 8/2/0.2 (V/V/V) was used as the acidic solvent system and the 2-methoxyethanol/0.2 M NaOH solution = 1/9 (V/V) was used as the alkaline solvent system. The ph-OH contents in the spruce milled wood lignin (SMWL) and the spruce Kraft lignin (SKL) were respectively quantified by the modified Delta epsilon-spectrum method as 1.078 and 4.348 mmol/g, which were comparable to the counterparts determined by P-31 Nuclear Magnetic Resonance Spectroscopy (P-31 NMR). The results revealed that the modified Delta epsilon-spectrum method can provide more accurate and reliable results compared to the conventional method.

  • 294. Chen, P.
    et al.
    Nishiyama, Y.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Quantifying the influence of dispersion interactions on the elastic properties of crystalline cellulose2021In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 28, no 17, p. 10777-10786Article in journal (Refereed)
    Abstract [en]

    Dispersion and electrostatic interactions both contribute significantly to the tight assembly of macromolecular chains within crystalline polysaccharides. Using dispersion-corrected density functional theory (DFT) calculation, we estimated the elastic tensor of the four crystalline cellulose allomorphs whose crystal structures that are hitherto available, namely, cellulose Iα, Iβ, II, IIII. Comparison between calculations with and without dispersion correction allows quantification of the exact contribution of dispersion to stiffness at molecular level.

  • 295.
    Chen, Pan
    et al.
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Nishiyama, Yoshiharu
    Univ Grenoble Alpes, CERMAV, CNRS, F-38000 Grenoble, France..
    Pingali, Sai Venkatesh
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA.;Oak Ridge Natl Lab, Ctr Struct Mol Biol, Oak Ridge, TN 37831 USA..
    O'Neill, Hugh M.
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA.;Oak Ridge Natl Lab, Ctr Struct Mol Biol, Oak Ridge, TN 37831 USA..
    Zhang, Qiu
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA.;Oak Ridge Natl Lab, Ctr Struct Mol Biol, Oak Ridge, TN 37831 USA..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Small Angle Neutron Scattering Shows Nanoscale PMMA Distribution in Transparent Wood Biocomposites2021In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992, Vol. 21, no 7, p. 2883-2890Article in journal (Refereed)
    Abstract [en]

    Transparent wood biocomposites based on PMMA combine high optical transmittance with excellent mechanical properties. One hypothesis is that despite poor miscibility the polymer is distributed at the nanoscale inside the cell wall. Small-angle neutron scattering (SANS) experiments are performed to test this hypothesis, using biocomposites based on deuterated PMMA and "contrast-matched" PMMA. The wood cell wall nanostructure soaked in heavy water is quantified in terms of the correlation distance d between the center of elementary cellulose fibrils. For wood/deuterated PMMA, this distance d is very similar as for wood/heavy water (correlation peaks at q approximate to 0.1 angstrom(-1)). The peak disappears when contrast-matched PMMA is used, indeed proving nanoscale polymer distribution in the cell wall. The specific processing method used for transparent wood explains the nanocomposite nature of the wood cell wall and can serve as a nanotechnology for cell wall impregnation of polymers in large wood biocomposite structures.

  • 296.
    Chen, Pan
    et al.
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Lo Re, Giada
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Ind & Mat Sci, SE-41296 Gothenburg, Sweden..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Surface modification effects on nanocellulose - molecular dynamics simulations using umbrella sampling and computational alchemy2020In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 8, no 44, p. 23617-23627Article in journal (Refereed)
    Abstract [en]

    Topochemical modification of nanocellulose particles, in particular acetylation, is commonly used to reduce hygroscopicity and improve their dispersibility in non-polar polymers. Despite enormous experimental efforts on cellulose surface modification, there is currently no comprehensive model which considers both (a) the specific interactions between nanocellulose particles and the surrounding liquid or polymer matrix, and (b) the interactions between the particles themselves. The second mechanism is therefore frequently ignored. The present approach is based on atomistic molecular dynamics (MD) simulations, where computational alchemy is used to calculate the changes in interactions between nanocellulose and the surrounding medium (liquid or polymer) upon modification. This is combined with another method, based on potential of mean force, to calculate interactions between particles. Results show that both contributions are of equal importance for nanoparticle surface acetylation effects. The proposed method is not restricted to either cellulose or acetylation, and has the prospect to find application in a broad context of nanomaterials design.

  • 297.
    Chen, Pan
    et al.
    Rhein Westfal TH Aachen, AICES Grad Sch, D-52062 Aachen, Germany..
    Ogawa, Yu
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Tokyo, Grad Sch Agr & Life Sci, Dept Biomat Sci, Bunkyo Ku, Tokyo 1138657, Japan..
    Nishiyama, Yoshiharu
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Grenoble Alpes, CERMAV, F-38000 Grenoble, France..
    Bergenstråhle Wohlert, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mazeau, Karim
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Grenoble Alpes, CERMAV, F-38000 Grenoble, France..
    Energetically favored alternative hydrogen bond of cellulose II and cellulose IIII2015In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 298.
    Chen, Pan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Terenzi, Camilla
    Wageningen Univ & Res, Wageningen, Netherlands..
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Heterogeneous dynamics in cellulose from molecular dynamics simulations2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 299.
    Chen, Pan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Derivat, Beijing 100081, Peoples R China..
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Water as an Intrinsic Structural Element in Cellulose Fibril Aggregates2022In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 13, no 24, p. 5424-5430Article in journal (Refereed)
    Abstract [en]

    While strong water association with cellulose in plant cell walls and man-made materials is well-established, its molecular scale aspects are not fully understood. The thermodynamic consequences of having water molecules located at the microfibril-microfibril interfaces in cellulose fibril aggregates are therefore analyzed by molecular dynamics simulations. We find that a thin layer of water molecules at those interfaces can be in a state of thermal equilibrium with water surrounding the fibril aggregates because such an arrangement lowers the free energy of the total system. The main reason is enthalpic: water at the microfibril- microfibril interfaces enables the cellulose surface hydroxyls to experience a more favorable electrostatic environment. This enthalpic gain overcomes the entropic penalty from strong immobilization of water molecules. Hence, those particular water molecules stabilize the cellulose fibril aggregates, akin to the role of water in some proteins. Structural and functional hypotheses related to this finding are presented.

  • 300.
    Chen, Pan
    et al.
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Zhao, Changjun
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Wang, Huanyu
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Li, Yiwei
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Tan, Guoqiang
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Shao, Ziqiang
    Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, Beijing 100081, Peoples R China..
    Nishiyama, Yoshiharu
    Univ Grenoble Alpes, CNRS, CERMAV, F-38000 Grenoble, France..
    Hu, Tao
    Shanghai Univ, Dept Mat Sci, Shanghai 200444, Peoples R China..
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Quantifying the Contribution of the Dispersion Interaction and Hydrogen Bonding to the Anisotropic Elastic Properties of Chitin and Chitosan2022In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 23, no 4, p. 1633-1642Article in journal (Refereed)
    Abstract [en]

    The elastic tensors of chitin and chitosan allomorphs were calculated using density functional theory (DFT) with and without the dispersion correction and compared with experimental values. The longitudinal Young's moduli were 114.9 or 126.9 GPa for alpha-chitin depending on the hydrogen bond pattern: 129.0 GPa for beta-chitin and 191.5 GPa for chitosan. Furthermore, the moduli were found to vary between 17.0 and 52.8 GPa in the transverse directions and between 2.2 and 15.2 GPa in shear. Switching off the dispersion correction led to a decrease in modulus by up to 63%, depending on the direction. The transverse Young's moduli of a-chitin strongly depended on the hydroxylmethyl group conformation coupled with the dispersion correction, suggesting a synergy between hydrogen bonding and dispersion interactions. The calculated longitudinal Young's moduli were, in general, higher than experimental values obtained in static conditions, and the Poisson's ratios were lower than experimental values obtained in static conditions.

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