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  • 51.
    Farahani, Saina Kishani
    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.
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hansson, Per
    Uppsala Univ, Uppsala, Sweden..
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Influence of solubility on the adsorption of different Xyloglucan fractions to cellulose model surfaces2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 52.
    Farhat, Wissam
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Stamm, Arne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Biundo, Antonino
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Fogelström, Linda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Syrén, Per-Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Enzymatic route for the synthesis of norcamphor lactone and its polymerization for applications as thermo-sensitive networks2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 258Article in journal (Other academic)
  • 53.
    Fogelström, Linda
    et al.
    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, Coating Technology.
    Norström, Emelie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Khabbaz, Farideh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Brucher, Jorg
    Holmen, Holmen Dev, Örnskoldsvik, Sweden..
    Malmström, Eva
    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. KTH Royal Inst Technol, Wallenberg Wood Sci Ctr, Stockholm, Sweden.;KTH Royal Inst Technol, Dept Fibre & Polymer Technol, Stockholm, Sweden..
    A fully green wood adhesive based on hemicelluloses derived from pulp processes2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 54.
    Francon, Hugo
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Benselfelt, Tobias
    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, Coating Technology.
    Granberg, Hjalmar
    RISE Bioecon, Stockholm, Sweden..
    Larsson, Per A.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, 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. KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    3D printable nanocellulose aerogels via a green crosslinking approach and a facile evaporation procedure2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 55.
    Frodeson, Stefan
    et al.
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Lindén, Pär
    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.
    Henriksson, Gunnar
    Karlstad Univ, Dept Engn & Chem Sci, Chem Engn, SE-65188 Karlstad, Sweden..
    Berghel, Jonas
    Karlstad Univ, Dept Engn & Chem Sci, Environm & Energy Syst, SE-65188 Karlstad, Sweden..
    Compression of Biomass Substances-A Study on Springback Effects and Color Formation in Pellet Manufacture2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 20Article in journal (Refereed)
    Abstract [en]

    In order to increase the use of a variated raw material base for pellet production with a maintained density level, knowledge of the biomaterials' ability to counteract any springback effects is essential. In this study, the springback effects were investigated for single press produced pellets from cellulose, hemicelluloses, pectin, and two woods at different moisture contents. The change in pellet coloring was also tested through a spectrophotometer for both xylan and carboxymethyl cellulose (CMC) pellets. The results show that the density of xylan pellets is much higher than glucomannan, for both green and cured pellets, and that the length of the pellets, as well as springback contribution, differ between the hemicelluloses. The study also presents results showing that both xylan and CMC pellets have a mutually identical spectrum and that the changes in the structure of xylan are not only related to moisture content, but are also pressure-related. The study also postulates that the color difference of the xylan pellets is a result of physical changes in the structure, as opposed to being of a chemical nature.

  • 56.
    Fu, Qiliang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), 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 Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hierarchically structured nanoporous template based on balsa wood2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 57.
    Fu, Qiliang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Honeycomb like templates prepared from balsa wood2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    In the current study, we have used sodium chlorite and sodium hydroxide as extraction solutions, to remove lignin and hemicelluloses from the Balsa (Ochroma Lagopus) wood tissues, without damaging the wood honeycomb architecture. Surface morphologies are studied using scanning electron microscopy (SEM). In addition, sugars analysis of the chemically extracted wood is reported. 

  • 58.
    Fu, Qiliang
    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.
    Yan, Min
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jungstedt, Erik
    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.
    Yang, Xuan
    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.
    Li, Yuanyuan
    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.
    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.
    Transparent plywood as a load-bearing and luminescent biocomposite2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 164, p. 296-303Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) structures in research studies were either thin and highly anisotropic or thick and isotropic but weak. Here, transparent plywood (TPW) laminates are investigated as load-bearing biocomposites with tunable mechanical and optical performances. Structure-property relationships are analyzed. The plies of TPW were laminated with controlled fiber directions and predetermined stacking sequence in order to control the directional dependence of modulus and strength, which would give improved properties in the weakest direction. Also, the angular dependent light scattering intensities were investigated and showed more uniform distribution. Luminescent TPW was prepared by incorporation of quantum dots (QDs) for potential lighting applications. TPW can be designed for large-scale use where multiaxial load-bearing performance is combined with new optical functionalities.

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  • 59. Geng, Lihong
    et al.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Zhan, Chengbo
    Ansari, Farhan
    Sharma, Priyanka R.
    Peng, Xiangfang
    Hsiao, Benjamin S.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Understanding the Mechanistic Behavior of Highly Charged Cellulose Nanofibers in Aqueous Systems2018In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, no 4, p. 1498-1506Article in journal (Refereed)
    Abstract [en]

    Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380-1360 mu mol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G') decreased dramatically at a given frequency threshold. This behavior is discussed in relation to the breakup of the entangled flocs and network in the suspension. The analysis of the mechanistic behavior of CNF aqueous suspensions by the crowding factor provides useful insight for fabricating high-performance nanocellulose-based materials.

  • 60.
    Geng, Shiyu
    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. Luleå Univ Technol, Div Mat Sci, Dept Engn Sci & Math, SE-97187 Luleå, Sweden.
    Yao, Kun
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Zhou, Qi
    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), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Oksman, Kristiina
    Luleå Univ Technol, Div Mat Sci, Dept Engn Sci & Math, SE-97187 Luleå, Sweden.;Univ Oulu, Fibre & Particle Engn, FI-90014 Oulu, Finland..
    High-Strength, High-Toughness Aligned Polymer-Based Nanocomposite Reinforced with Ultralow Weight Fraction of Functionalized Nanocellulose2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 10, p. 4075-4083Article in journal (Refereed)
    Abstract [en]

    Multifunctional lightweight, flexible, yet strong polymer-based nanocomposites are highly desired for specific applications. However, the control of orientation and dispersion of reinforcing nanoparticles and the optimization of the interfacial interaction still pose substantial challenges in nanocellulose-reinforced polymer composites. In this study, poly(ethylene glycol) (PEG)-grafted cellulose nanofibers have demonstrated much better dispersion in a poly(lactic acid) (PLA) matrix as compared to unmodified nanocellulose. Through a uniaxial drawing method, aligned PLA/nanocellulose nanocomposites with high strength, high toughness, and unique optical behavior can be obtained. With the incorporation of 0.1 wt % of the PEG-grafted cellulose nanofibers in PLA, the ultimate strength of the aligned nanocomposite reaches 343 MPa, which is significantly higher than that of other aligned PLA-based nanocomposites reported previously. Moreover, its ultimate strength and toughness are enhanced by 39% and 70%, respectively, as compared to the aligned nanocomposite reinforced with unmodified cellulose nanofibers. In addition, the aligned nanocomposite film is highly transparent and possesses an anisotropic light scattering effect, revealing its significant potential for optical applications.

  • 61.
    Ghanadpour, Maryam
    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.
    Carosio, F.
    Ruda, M. C.
    Wågberg, 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.
    Tuning the Nanoscale Properties of Phosphorylated Cellulose Nanofibril-Based Thin Films to Achieve Highly Fire-Protecting Coatings for Flammable Solid Materials2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 38, p. 32543-32555Article in journal (Refereed)
    Abstract [en]

    Ultrathin nanocomposite films were prepared by combining cellulose nanofibrils (CNFs) prepared from phosphorylated pulp fibers (P-CNF) with montmorillonite (MMT), sepiolite (Sep) clay, or sodium hexametaphosphate (SHMP). The flame-retardant and heat-protective capability of the prepared films as casings for a polyethylene (PE) film was investigated. Heating the coated PE in air revealed that the polymer film was thoroughly preserved up to at least 300 °C. The P-CNF/MMT coatings were also able to completely prevent the ignition of the PE film during cone calorimetry, but neither the P-CNF/Sep nor the P-CNF/SHMP coating could entirely prevent PE ignition. This was explained by the results from combined thermogravimetry Fourier transform infrared spectroscopy, which showed that the P-CNF/MMT film was able to delay the release of PE decomposition volatiles and shift its thermal degradation to a higher temperature. The superior flame-retardant performance of the P-CNF/MMT films is mainly attributed to the unique compositional and structural features of the film, where P-CNF is responsible for increasing the char formation, whereas the MMT platelets create excellent barrier and thermal shielding properties by forming inorganic lamellae within the P-CNF matrix. These films showed a tensile strength of 304 MPa and a Young's modulus of 15 GPa with 10 wt % clay so that this composite film was mechanically stronger than the previously prepared CNF/clay nanopapers containing the same amount of clay. 

  • 62.
    Ghanadpour, Maryam
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wicklein, Bernd
    Carosio, Federico
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    All-natural and highly flame-resistant freeze-cast foams based on phosphorylated cellulose nanofibrils2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 8, p. 4085-4095Article in journal (Refereed)
    Abstract [en]

    Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application. Here, light-weight and flame-resistant nanostructured foams are produced by combining cellulose nanofibrils prepared from phosphorylated pulp fibers (P-CNF) with microfibrous sepiolite clay using the freeze-casting technique. The resultant nanocomposite foams show excellent flame-retardant properties such as self-extinguishing behavior and extremely low heat release rates in addition to high flame penetration resistance attributed mainly to the intrinsic charring ability of the phosphorylated fibrils and the capability of sepiolite to form heat-protective intumescent-like barrier on the surface of the material. Investigation of the chemical structure of the charred residue by FTIR and solid state NMR spectroscopy reveals the extensive graphitization of the carbohydrate as a result of dephosphorylation of the modified cellulose and further dehydration due to acidic catalytic effects. Originating from the nanoscale dimensions of sepiolite particles, their high specific surface area and stiffness as well as its close interaction with the phosphorylated fibrils, the incorporation of clay nanorods also significantly improves the mechanical strength and stiffness of the nanocomposite foams. The novel foams prepared in this study are expected to have great potential for application in sustainable building construction.

  • 63.
    Gioia, Claudio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Lo Re, Giada
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH Royal Inst Technol, Stockholm, 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. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Tunable polymer systems containing well-characterized derivatives from lignin2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 64.
    Gioia, Claudio
    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.
    Lo Re, Giada
    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.
    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.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Tunable thermosetting epoxies based on fractionated and well-characterized lignins2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Article in journal (Refereed)
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  • 65.
    Giummarella, Nicola
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fundamental Aspects of Lignin Carbohydrate Complexes (LCC): Mechanisms, Recalcitrance and Material concepts2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Covalent bonds between lignin and carbohydrates, forming a matrix referred to as lignin carbohydrate complexes (LCC), remain one of the most controversial topics in wood chemistry. A key issue is whether they are formed during chemical and mechanical pretreatments of the compact wood structure or actually present in wood prior to isolation. A fundamental understanding of their origin and reactivity is vital to unravel their role in wood formation and recalcitrance. Recalcitrance, specifically, has affected the successful development of effective and clean fractionation of wood polymers.

    To address the above-mentioned concerns, we have developed a novel mild universal and quantitative fractionation protocol of LCC that, when combined with robust spectroscopic analytical tools, including a variety of NMR techniques, GC MS and SEC, reveals deeper insights into the molecular structure of LCC.

    This method was applied to both hardwood and softwood LCCs and revealed interesting findings on molecular-level regulatory mechanism for lignin carbohydrate (LC) bond formation such as the role of acetylation in hemicelluloses. Moreover, the role of LC bonds on recalcitrance during subcritical water extraction was unveiled.

    Bio-mimicking in vitro lignin polymerization was adopted to investigate whether LC bonds are native or formed during isolation from wood. For the first time, direct evidence lending support that they are formed in wood cells was demonstrated, thus corroborating the mechanisms suggested in the literature.  

    Furthermore, based on the overall LCC study, we suggest a sequence for how LC bonds may form in vitro.

    Finally, of special interest to material science, the unveiled LC bond formation mechanism inspired a green, biomimetic, one-pot synthesis of functionalized lignin starting from monomeric components. Excellent selectivity of functionalization is reported and production of lignin-based recyclable materials, based on the premise of this functionalization philosophy, is discussed.

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  • 66.
    Giummarella, Nicola
    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.
    Balakshin, Mikhail
    Koutaniemi, Sanna
    Kärkönen, Anna
    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.
    Nativity of lignin carbohydrate bonds substantiated by biomimetic synthesis2019In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, no 20, p. 5591-5601Article in journal (Refereed)
    Abstract [en]

    The question of whether lignin is covalently linked to carbohydrates in native wood, forming what is referred to as lignin–carbohydrate complexes (LCCs), still lacks unequivocal proof. This is mainly due to the need to isolate lignin from woody materials prior to analysis, under conditions leading to partial chemical modification of the native wood polymers. Thus, the correlation between the structure of the isolated LCCs and LCCs in situ remains open. As a way to circumvent the problematic isolation, biomimicking lignin polymerization in vivo and in vitro is an interesting option. Herein, we report the detection of lignin–carbohydrate bonds in the extracellular lignin formed by tissue-cultured Norway spruce cells, and in modified biomimetic lignin synthesis (dehydrogenation polymers). Semi-quantitative 2D heteronuclear singular quantum coherence (HSQC)-, 31P -, and 13C-NMR spectroscopy were applied as analytical tools. Combining results from these systems, four types of lignin–carbohydrate bonds were detected; benzyl ether, benzyl ester, γ-ester, and phenyl glycoside linkages, providing direct evidence of lignin–carbohydrate bond formation in biomimicked lignin polymerization. Based on our findings, we propose a sequence for lignin–carbohydrate bond formation in plant cell walls.

  • 67.
    Giummarella, Nicola
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Gioia, Claudio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Civil, Chemical, Environmental and Materials Engineering. Universita´ di Bologna.
    Lawoko, Martin
    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.
    A One-Pot Biomimetic Synthesis of Selectively Functionalized Lignins from Monomers: A Green Functionalization Platform2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 21, no 11, p. 5579-5585Article in journal (Refereed)
    Abstract [en]

    Lignin is the most abundant renewable source of phenolic compound with great application potential in renewable materials, biofuels and platform chemicals. Current technology for producing cellulose-rich fibers co-produces heterogeneous lignin, which includes an untapped source of monomeric phenolics. One such monomer also happen to be the main monomer in soft wood lignin biosynthesis, namely coniferyl alcohol. Herein, we investigate the potential of coniferyl alcohol as a platform monomer for the biomimetic production of tailored functionalized oligolignols with desirable properties for material synthesis. Accordingly, a bifunctional molecule with at least one carboxyl-ended functionality is included with coniferyl alcohol in biomimetic lignin synthesis to, in one-pot, produce a functionalized lignin. The functionalization mechanism is a nucleophilic addition reaction to quinone methide intermediate of lignin polymerization. The solvent systems applied were pure water or 50% aqueous acetone. Several bi-functional molecules differing in the second functionality were successfully inserted in the lignin demonstrating the platform component of this work. Detailed characterizations were performed by a combination of NMR techniques which include 1H NMR, COSY-90, 31P NMR, 13C NMR, 13C APT, HSQC, HMBC and HSQC TOCSY. Excellent selectivity towards benzylic carbon and high functionalization degree were noted. The structure of lignin was tailored through solvent system choice, with the 50% aqeuous acetone producing a skeletal structure favorable for high functionalization degrees. Finally, material concepts are demonstrated using classical Thiol-ene- and Diels Alder- chemistries to show potential for thermoset- and thermoplastic- concepts, respectively. The functionalization concept presents unprecedentent opportunities for green production of lignin-based recyclable biomaterials.

  • 68.
    Giummarella, Nicola
    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.
    Lindén, Pär 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.
    Areskogh, Dimitri
    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.
    Fractional profiling of kraft lignin structure: Unravelling insights on lignin reaction mechanisms2019In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485Article in journal (Refereed)
    Abstract [en]

    The kraft process is the main process used for the production of chemical pulps. In this process, an efficient delignification is achieved, yielding bleachable grade pulps. In recent years, there has been interest in valorization of the dissolved lignins, prompted by the development of technically feasible processes to retrieve it from the black liquor. However, the structural-, functional-, and size-related heterogeneities of lignin present both analytical challenges and challenges in developing new applications. Hence, refining of the crude product is essential. Herein, advanced NMR characterization (13C NMR, APT/DEPT NMR, 31P NMR, HSQC, HMBC, HSQC-TOCSY) was applied to profile the detailed molecular structures of refined kraft lignins and unravel mechanistic insights on important lignin reactions during kraft pulping. From this structural analysis of the lignins, a model oligomer was synthesized and analyzed to provide support to the effect that a retro-aldol reaction in combination with radical recombination reactions play a significant role in the formation of the reconstituted fraction of kraft lignin. In this regard, a new type of linkage accounting for approximately 10% of the interunits in kraft lignin is reported.

  • 69.
    Giummarella, Nicola
    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, Wood Chemistry and Pulp Technology.
    Pu, Yunqiao
    Ragauskas, Arthur J
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    A Critical Review on the Analysis of Lignin Carbohydrate Bonds2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270Article in journal (Refereed)
    Abstract [en]

    Replacing fossil-based resources with renewable alternatives is generally acknowledged as a critical component to address several of today's environmental concerns. In this context, lignocellulosic biomass is an attractive, sustainable resource. However, the constitutional biopolymers of interest are locked in the structural complexity of the plant cell walls, which defines their properties and contributes to fractionation recalcitrance. One of the key suspects restricting fractionation of the biopolymers in high yield is the presence of lignin-carbohydrate bonds forming a matrix referred to as Lignin-Carbohydrate Complexes (LCC). Nevertheless, covalent bonds between lignin and carbohydrates, remain one of the most controversial topics in lignocellulose chemistry. This challenge can be attributed to the slow progress made in their research, which also forms the basis for this review. Herein, we will critically discuss the literature with a particular focus on the latest characterization and analytical techniques. Discussions on existing techniques and, importantly the drawbacks with them should be compelling to researchers in the area, especially at this time when crucial issues surrounding the realization of biorefineries need to be addressed.

  • 70.
    Goliszek, M.
    et al.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Podkoscielna, B.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Fila, K.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Riazanova, A. V.
    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.
    Aminzadeh, Selda
    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.
    Sevastyanova, O.
    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.
    Gun'ko, V. M.
    Chuiko Inst Surface Chem, 17 Gen Naumov Str, UA-03164 Kiev, Ukraine..
    Synthesis and structure characterization of polymeric nanoporous microspheres with lignin2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 5843-5862Article in journal (Refereed)
    Abstract [en]

    Nanoporous microspheres with divinylbenzene (DVB), styrene (St), and lignin were synthesized by an emulsion-suspension polymerization method. Several types of lignins were used: (1) kraft lignin before (L-unmod) and after modification with methacryloyl chloride (L-Met) and (2) low-molecular-weight kraft lignin unmodified (LWL-unmod) and modified with methacrylic anhydride (LWL-Met). LWL was prepared by ultrafiltration of industrial black liquor using a ceramic membrane with a molecular weight (Mw) cut-off of 5 kDa. The synthesis was optimized by addition of different amounts of lignins. The microsphere texture was characterized using low-temperature nitrogen adsorption and small angle X-ray scattering analyses. The microspheres were nano- and mesoporous with a specific surface area in the range of 0.1-409 m(2)/g. The morphology of the copolymers was studied using field emission scanning electron microscopy and atomic force microscopy. The thermal properties were studied using differential scanning calorimetry and thermogravimetric analysis methods. A significant difference in the microsphere roughness is affected by lignins due to the presence of lignin nanoparticles at the surface of the microspheres. Molecular modeling was used to predict the sorption properties of the copolymers affected by various fields around the particles. The particle size, polydispersity and zeta potential of the St + DVB, L-Met + St + DVB and L-unmod + St + DVB samples were measured by dynamic light scattering. Additionally, the point of zero charge of the samples was determined using potentiometric titration. The materials studied have a great potential for sorption processes due to their developed porosity and the presence of a number of active surface functionalities. [GRAPHICS] .

  • 71.
    Goliszek, M.
    et al.
    Department of Polymer Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, Lublin, 20-031, Poland.
    Wiącek, A. E.
    Department of Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, Lublin, 20-031, Poland.
    Wawrzkiewicz, M.
    Department of Inorganic Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, Lublin, 20-031, Poland.
    Sevastyanova, Olena
    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.
    Podkościelna, B.
    Department of Polymer Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Sq. 3, Lublin, 20-031, Poland.
    The impact of lignin addition on the properties of hybrid microspheres based on trimethoxyvinylsilane and divinylbenzene2019In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 120, article id 109200Article in journal (Refereed)
    Abstract [en]

    Hybrid microspheres of trimethoxyvinylsilane, divinylbenzene and lignin were synthesized by a suspension polymerization method. Commercially available alkali lignin and the methanol fraction of softwood kraft lignin were used as the bio-component of polymeric microspheres. The methanol fraction of lignin had a high content of phenolic groups and low molecular weight which are desirable features for further methacrylation. The physicochemical and electrokinetic properties of the synthesized materials were analyzed in detail. The preliminary modification of the hybrids with lignin had a noticeable positive effect on the stability and electrokinetic properties of the final products compared to those of unmodified microspheres composed of divinylbenzene and trimethoxyvinylsilane (DVB-TMVS). Thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis, and the morphology was studied using scanning electron microscopy. The microsphere texture was characterized using low-temperature nitrogen adsorption. The microspheres were mesoporous with a specific surface area in the range of 149–305 m2/g. The porosity of the hybrid materials was influenced by the type and modification of the lignin; microspheres with modified lignin in general had more developed porous structures. The applicability of the porous materials obtained as sorbents for the removal of dyes was confirmed in a batch experiment. The mechanism of interactions between dyes and a bio-sorbent containing lignin may involve electrostatic interactions between the positively charged nitrogen atoms of the dye molecule and the dissociated functional groups of the adsorbent, hydrogen bonding and π-π interactions.

  • 72.
    Goliszek, Marta
    et al.
    Marie Curie Sklodowska Univ, Fac Chem, Dept Polymer Chem, M Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Podkoscielna, Beata
    Marie Curie Sklodowska Univ, Fac Chem, Dept Polymer Chem, M Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Sevastyanova, Olena
    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.
    Gawdzik, Barbara
    Marie Curie Sklodowska Univ, Fac Chem, Dept Polymer Chem, M Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Chabros, Artur
    Marie Curie Sklodowska Univ, Fac Chem, Dept Polymer Chem, M Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    The Influence of Lignin Diversity on the Structural and Thermal Properties of Polymeric Microspheres Derived from Lignin, Styrene, and/or Divinylbenzene2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 18, article id 2847Article in journal (Refereed)
    Abstract [en]

    This work investigates the impact of lignin origin and structural characteristics, such as molecular weight and functionality, on the properties of corresponding porous biopolymeric microspheres obtained through suspension-emulsion polymerization of lignin with styrene (St) and/or divinylbenzene (DVB). Two types of kraft lignin, which are softwood (Picea abies L.) and hardwood (Eucalyptus grandis), fractionated by common industrial solvents, and related methacrylates, were used in the synthesis. The presence of the appropriate functional groups in the lignins and in the corresponding microspheres were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR), while the thermal properties were studied by differential scanning calorimetry (DSC). The texture of the microspheres was characterized using low-temperature nitrogen adsorption. The swelling studies were performed in typical organic solvents and distilled water. The shapes of the microspheres were confirmed with an optical microscope. The introduction of lignin into a St and/or DVB polymeric system made it possible to obtain highly porous functionalized microspheres that increase their sorption potential. Lignin methacrylates created a polymer network with St and DVB, whereas the unmodified lignin acted mainly as an eco-friendly filler in the pores of St-DVB or DVB microspheres. The incorporation of biopolymer into the microspheres could be a promising alternative to a modification of synthetic materials and a better utilization of lignin.

  • 73.
    Gowda, Krishne, V
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Brouzet, Christophe
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lefranc, Thibault
    Univ Claude Bernard, Univ Lyon, ENS Lyon, CNRS,Lab Phys, F-69342 Lyon, France..
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Effective interfacial tension in flow-focusing of colloidal dispersions: 3-D numerical simulations and experiments2019In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 876, p. 1052-1076, article id PII S0022112019005664Article in journal (Refereed)
    Abstract [en]

    An interface between two miscible fluids is transient, existing as a non-equilibrium state before complete molecular mixing is reached. However, during the existence of such an interface, which typically occurs at relatively short time scales, composition gradients at the boundary between the two liquids cause stresses effectively mimicking an interfacial tension. Here, we combine numerical modelling and experiments to study the influence of an effective interfacial tension between a colloidal fibre dispersion and its own solvent on the flow in a microfluidic system. In a flow-focusing channel, the dispersion is injected as core flow that is hydrodynamically focused by its solvent as sheath flows. This leads to the formation of a long fluid thread, which is characterized in three dimensions using optical coherence tomography and simulated using a volume of fluid method. The simulated flow and thread geometries very closely reproduce the experimental results in terms of thread topology and velocity flow fields. By varying the interfacial tension numerically, we show that it controls the thread development, which can be described by an effective capillary number. Furthermore, we demonstrate that the applied methodology provide the means to measure the ultra-low but dynamically highly significant effective interfacial tension.

  • 74.
    Guccini, Valentina
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.
    Carlson, Annika
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Yu, Shun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden .
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Salazar-Alvarez, German
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden .
    Highly proton conductive membranes based on carboxylated cellulose nanofibres and their performance in proton exchange membrane fuel cells2019In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 43, p. 25032-25039Article in journal (Refereed)
    Abstract [en]

    The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in situ as a function of CNF surface charge density (600 and 1550 μmol g−1), counterion (H+ or Na+), membrane thickness and fuel cell relative humidity (RH 55 to 95%). The structural evolution of the membranes as a function of RH, as measured by Small Angle X-ray Scattering, shows that water channels are formed only above 75% RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (H+ or Na+). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm−1 at 30 °C between 65 and 95% RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈30% thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells.

  • 75.
    Guccini, Valentina
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Yu, Shun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Agthe, Michael
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;Univ Hamburg, Ctr Free Electron Laser Sci, D-22761 Hamburg, Germany..
    Gordeyeva, Korneliya
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Trushkina, Yulia
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Fall, Andreas
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden..
    Schuetz, Christina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;Univ Luxembourg, Phys & Mat Sci Res Unit, L-1511 Luxembourg, Luxembourg..
    Salazar-Alvarez, German
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Inducing nematic ordering of cellulose nanofibers using osmotic dehydration2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 48, p. 23157-23163Article in journal (Refereed)
    Abstract [en]

    The formation of nematically-ordered cellulose nanofiber (CNF) suspensions with an order parameter f(max) approximate to 0.8 is studied by polarized optical microscopy, small-angle X-ray scattering (SAXS), and rheological measurements as a function of CNF concentration. The wide range of CNF concentrations, from 0.5 wt% to 4.9 wt%, is obtained using osmotic dehydration. The rheological measurements show a strong entangled network over all the concentration range whereas SAXS measurements indicate that at concentrations >1.05 wt% the CNF suspension crosses an isotropic-anisotropic transition that is accompanied by a dramatic increase of the optical birefringence. The resulting nanostructures are modelled as mass fractal structures that converge into co-existing nematically-ordered regions and network-like regions where the correlation distances decrease with concentration. The use of rapid, upscalable osmotic dehydration is an effective method to increase the concentration of CNF suspensions while partly circumventing the gel/glass formation. The facile formation of highly ordered fibers can result in materials with interesting macroscopic properties.

  • 76.
    Gunnarsson, Maria
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden..
    Bernin, Diana
    Univ Gothenburg, Swedish NMR Ctr, SE-40530 Gothenburg, Sweden.;Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem React Engn, S-41296 Gothenburg, Sweden..
    Ostlund, Asa
    RISE Bioecon, Res Inst Sweden, Drottning Kristinas Vag 67, S-11428 Stockholm, Sweden..
    Hasani, Merima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Div Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Techno..
    The CO2 capturing ability of cellulose dissolved in NaOH(aq) at low temperature2018In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 20, no 14, p. 3279-3286Article in journal (Refereed)
    Abstract [en]

    Herein, we explore the intrinsic ability of cellulose dissolved in NaOH(aq) to reversibly capture CO2. The stability of cellulose solutions differed significantly when adding CO2 prior to or after the dissolution of cellulose. ATR-IR spectroscopy on cellulose regenerated from the solutions, using ethanol, revealed the formation of a new carbonate species likely to be cellulose carbonate. To elucidate the interaction of cellulose with CO2 at the molecular level, a C-13 NMR spectrum was recorded on methyl -d-glucopyranoside (MeO-Glcp), a model compound, dissolved in NaOH(aq), which showed a difference in chemical shift when CO2 was added prior to or after the dissolution of MeO-Glcp, without a change in pH. The uptake of CO2 was found to be more than twice as high when CO2 was added to a solution after the dissolution of MeO-Glcp. Altogether, a mechanism for the observed CO2 capture is proposed, involving the formation of an intermediate cellulose carbonate upon the reaction of a cellulose alkoxide with CO2. The intermediate was observed as a captured carbonate structure only in regenerated samples, while its corresponding NMR peak in solution was absent. The reason for this is plausibly a rather fast hydrolysis of the carbonate intermediate by water, leading to the formation of CO32-, and thus increased capture of CO2. The potential of using carbohydrates as CO2 capturing agents in NaOH(aq) is shown to be simple and resource-effective in terms of the capture and regeneration of CO2.

  • 77.
    Gunnarsson, Maria
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Forest Prod & Chem Engn, S-41296 Gothenburg, Sweden..
    Hasani, Merima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Div Forest Prod & Chem Engn, S-41296 Gothenburg, Sweden.
    Bernin, Diana
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem React Engn, S-41296 Gothenburg, Sweden..
    Influence of urea on methyl beta-D-glucopyranoside in alkali at different temperatures2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 18, p. 9413-9422Article in journal (Refereed)
    Abstract [en]

    The dissolution efficiency plays an important role on the properties of regenerated cellulose-based products. Urea is known to be one of the additives aiding to improve cellulose dissolution in the NaOH(aq) system. The acting mechanism caused by urea has been debated and one of the hypothesis is that urea could induce a conformational change on cellulose, which promotes dissolution. Here we used NMR spectroscopy on a model system for cellulose, namely, methyl beta-D-glucopyranoside (beta-MeO-Glcp) and compared chemical shifts and J couplings, which both are indicators for conformational changes, as a function of temperature and upon the addition of urea. We found that in NaOH(aq), the hydroxymethyl group changes its conformation in favour of the population of the gt rotamer, while the presence of urea induced temperature dependent conformational changes. Heteronuclear Overhauser effect experiments showed that urea associates with cellulose but in a non-specific manner. This suggests that urea rather than binding to the carbohydrate, changes the chemical environment inducing a change in conformation of beta-MeO-Glcp and likely also for cellulose when dissolved in NaOH(aq) with urea.

  • 78.
    Gunnarsson, Maria
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden..
    Hasani, Merima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers University of Technology, Stockholm, SE-100 44, Sweden.
    Bernin, Diana
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem React Engn, SE-41296 Gothenburg, Sweden..
    The potential of magnetisation transfer NMR to monitor the dissolution process of cellulose in cold alkali2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 18, p. 9403-9412Article in journal (Refereed)
    Abstract [en]

    Cellulose is the most important biopolymer on earth and, when derived from e.g. wood, a promising alternative to for example cotton, which exhibits a large environmental burden. The replacement depends, however, on an efficient dissolution process of cellulose. Cold aqueous alkali systems are attractive but these solvents have peculiarities, which might be overcome by understanding the acting mechanisms. Proposed dissolution mechanisms are for example the breakage of hydrophobic interactions and partly deprotonation of the cellulose hydroxyl groups. Here, we performed a mechanistic study using equimolar aqueous solutions of LiOH, NaOH and KOH to elucidate the dissolution process of microcrystalline cellulose (MCC). The pH was the highest for KOH(aq) followed by NaOH(aq) and LiOH(aq). We used a combination of conventional and advanced solution-state NMR methods to monitor the dissolution process of MCC by solely increasing the temperature from - 10 to 5 degrees C. KOH(aq) dissolved roughly 25% of the maximum amount of MCC while NaOH(aq) and LiOH(aq) dissolved up to 70%. Water motions on nanoscale timescales present in non-frozen water, remained unaffected on the addition of MCC. Magnetisation transfer (MT) NMR experiments monitored the semi-rigid MCC as a function of temperature. Interestingly, although NaOH(aq) and LiOH(aq) were able to dissolve a similar amount at 5 degrees C, MT spectra revealed differences with increasing temperature, suggesting a difference in the swollen state of MCC in LiOH(aq) already at - 10 degrees C. Furthermore, MT NMR shows a great potential to study the water exchange dynamics with the swollen and semi-rigid MCC fraction in these systems, which might give valuable insights into the dissolution mechanism in cold alkali.

  • 79.
    Guo, Yaxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Yao, Zhaoyang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Timmer, Brian J. J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Sheng, Xia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Fan, Lizhou
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Li, Yuanyuan
    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.
    Zhang, Fuguo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, Dalian 116024, Peoples R China..
    Boosting nitrogen reduction reaction by bio-inspired FeMoS containing hybrid electrocatalyst over a wide pH range2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 62, p. 282-288Article in journal (Refereed)
    Abstract [en]

    A facile preparation of bio-inspired and morphology controllable catalytic electrode FeS@MoS2/CFC, featuring a carbon fiber cloth (CFC) covered with FeS dotted MoS2 nanosheets, has been established. Synergy between the CFC as a self-standing conductive substrate and the FeS nanoparticle dotted MoS2 nanosheets with abundant active sites makes the noble-metal-free catalytic electrode FeS@MoS2/CFC highly efficient in nitrogen reduction reaction (NRR), with an ammonia production rate of 8.45 mu g h(-1) cm(-2) and excellent long-term stability at -0.5 V in pH neutral electrolyte. Further electrolysis in acidic and alkaline electrolytes revealed the overall NRR catalytic activity of this electrode over a wide pH range.

  • 80.
    Hajian, Alireza
    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.
    Cellulose–Assisted Dispersion of Carbon Nanotubes: From Colloids to Composites2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is a challenge to disperse nanoparticles to obtain a nanostructured composite. This thesis aims at providing a new route to fabricate carbon nanotube (CNT) composites and suggests mechanisms for nanocellulose–CNT interactions. This route is based on unmodified CNT dispersed in water with the help of nanocellulose. Chemical functionalization of the CNTs and the addition of surfactants are avoided. Thus, the mechanical and electrical properties of such nanotube composites can be improved.

    Cellulose derivatives can disperse and stabilize carbon nanotubes in water. Nanocellulose particles, such as cellulose nanofibrils (CNF), are a new form of cellulose derivatives that are able to disperse and stabilize untreated carbon nanotubes in water. The utilization of the hybrid CNF–CNT dispersions are shown to lead to strong nanostructured composites with high nanotube content and conductivity. The mechanism behind the dispersive action of nanocellulose for nanotubes is explored and studied in detail. The dispersive ability of the nanocellulose leads to improved properties of CNF–CNT composites.

    Apart from studies of structure and properties of composite fibers and films, two different functional materials are studied in detail. One is to form conductive patterns on cellulose nanopaper for the stable function of printed electronics in various environmental conditions and during handling. The second is to use a water-soluble cellulosic polymer–nanotube dispersion to fabricate superelastic aerogels without any chemical crosslinking or the addition of another component. This makes the aerogels easily recyclable (redispersible in water) and opens a new route for recyclable superelastic CNT composite aerogels.

  • 81.
    Hajian, Alireza
    et al.
    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.
    Conductive and strong nanocomposites based on cellulose nanofibrils and carbon nanotubes2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    Single-wall carbon nanotubes (SWNTs) can be dispersed with the aid of cellulose nanofibrils (CNF) in aqueous medium. The dispersions have high stability and quality that can be utilized into self-assembly of functional composites having high electrical conductivity and strength. The composites were then carefully analyzed in terms of their mechanical and electrical properties as well as dispersion quality. 

  • 82.
    Hajian, Alireza
    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.
    Fu, Qiliang
    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.
    Berglund, 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.
    Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 159, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Deformation mechanisms are largely unknown for superelastic carbon nanotube (CNT) aerogels, and this hampers materials design efforts. The CNT network in the cell walls is typically crosslinked or connected by a thermoset polymer phase. In order to create a recyclable superelastic aerogel, unmodified single or multi-walled CNTs were dispersed in water by adding to aqueous carboxymethyl cellulose (CMC) solution. Directional freeze-drying was used to form honeycombs with cell walls of random-in-the-plane CNTs in CMC matrix. Cell wall morphology and porosity were studied and related to CNT type and content, as well as elastic or plastic buckling of the cell walls under deformation. CMC acts as a physical crosslinker for the CNTs in a porous cell wall. Aerogel structure and properties were characterized before and after recycling. The conductivity of the composite aerogel with a density of 10 kg/m3, 99% porosity and 50 wt % single-walled CNT exceeds 0.5 S/cm. The potential of these superelastic and conductive aerogels for applications such as mechanoresponsive materials was examined in cyclic conductivity tests at different strains. This opens a new route for recyclable superelastic CNT composite aerogels, avoiding material loss, chemical treatment or addition of other components.

  • 83.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindstrom, Stefan
    Linkoping Univ, Div Solid Mech, Dept Management & Engn, Linkoping, Sweden..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nanocellulose as dispersant for carbon nanotube suspensions2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 84.
    Hajian, Alireza
    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.
    Wang, Zhen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    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.
    Hamedi, Mahiar M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose Nanopaper with Monolithically Integrated Conductive Micropatterns2019In: Advanced Electronic Materials, ISSN 2199-160X, Vol. 5, no 3, article id 1800924Article in journal (Refereed)
    Abstract [en]

    This work presents a route to fabricate micropatterned conductive structures where the conductors are monolithically integrated with nanocellulose-based paper. To fabricate conductive features, microstructures are patterned on filter papers using wax-printing, followed by vacuum filtration of carbon nanotubes (CNTs) or silver nanowires (AgNWs) dispersed in aqueous cellulose nanofibrils (CNFs). These patterns are then laminated onto a pure CNF substrate (both in gel-state) and dried to form cellulose nanopapers with integrated conductive micropatterns. Resolutions of the conductive features are shown down to 400 µm wide, 250 nm thick, and with conductivity values of 115 ± 5 S cm −1 for the CNF–CNT and 3770 ± 230 S cm −1 for the CNF–AgNW micropatterns. The nanopaper and the conductive patterns both constitute random fibrous networks, and they display similar ductility and swelling behavior in water. Thus, the integrated conductive micropatterns can withstand folding, as well as wetting cycles. This stability of the micropatterns makes them useful in various devices based on nanocellulose substrates. As an example, an electroanalytical nanopaper device that operates in wet conditions is demonstrated.

  • 85.
    Halysh, Vita
    et al.
    Igor Sikorsky Kyiv Polytech Inst, Peremogy Ave 37-4, UA-03056 Kiev, Ukraine.;Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Sevastyanova, Olena
    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.
    de Carvalho, Danila Morais
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Riazanova, Anastasiia
    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.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gomelya, Mykola
    Igor Sikorsky Kyiv Polytech Inst, Peremogy Ave 37-4, UA-03056 Kiev, Ukraine..
    Effect of oxidative treatment on composition and properties of sorbents prepared from sugarcane residues2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 139, article id UNSP 111566Article in journal (Refereed)
    Abstract [en]

    Efficient sorbents for the removal of cationic dye were prepared from sugarcane bagasse (stalk) and straw (leaves) by oxidative pre-treatment with hydrogen peroxide (H2O2) in acetic acid. The effects of variables, such as concentration of H2O2, temperature and time on the properties of the fiber sorbents obtained were studied according to a 2(3) full-factorial design. For comparison, an oxidative treatment of sugarcane biomass with glacial acetic acid was also used. The yields of the materials obtained and their chemical composition were characterized and compared. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy and benzene vapor adsorption were used to investigate the structural properties and morphology of the initial materials and sorbents. The sorption of methylene blue dye was used to assess the efficiency of dye removal by the sorbents. The pre-treatment conditions significantly affected the sorbent yield, their chemical composition (contents of cellulose, lignin and ash) as well as their sorption properties. The cellulosic sorbent (C-sorbent) from sugarcane bagasse obtained by pre-treatment with H2O2 in acetic acid and the lignocellulosic sorbent (LC-sorbent) from sugarcane straw obtained by pre-treatment with glacial acetic acid, had the highest sorption capacity for the methylene blue dye. For both types of sorbents, the sorption capacity increased with chemical pretreatment as a result of an increase in pore volume.

  • 86.
    Halysh, Vita
    et al.
    Igor Sikorsky Kyiv Polytech Inst, Fac Chem Engn, Dept Ecol & Technol Plant Polymers, Peremogy Avenu 37-4, UA-03056 Kiev, Ukraine.;Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Sevastyanova, Olena
    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.
    Riazanova, Anastasia V.
    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.
    Pasalskiy, Bogdan
    Kyiv Natl Univ Trade & Econ, Kyoto Str 19, UA-02156 Kiev, Ukraine..
    Budnyak, Tetyana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kartel, Mykola
    Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Walnut shells as a potential low-cost lignocellulosic sorbent for dyes and metal ions2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 8, p. 4729-4742Article in journal (Refereed)
    Abstract [en]

    Currently, it is necessary to develop new methods and materials for solving the problem of environmental pollution by various toxicants. For these purposes, vegetal materials can be used. In this study, efficient low-cost sorbents based on walnut shells, an agro-industrial by-product, were prepared by treatment with acetic acid or a mixture of acetic acid and hydrogen peroxide. It was shown that the treatments significantly affected the composition and structure of walnut shells and their sorption properties with respect to organic dyes (methylene blue, methyl violet, and murexide) and heavy metal ions. Methylene blue dye was used for additional studies on the effect of pH, contact time and kinetics of sorption. The maximum adsorption rate of the dye occurred within the first 30 min of contact, during which the concentration of methylene blue in the solution was reduced by more than half. Full sorption equilibrium was reached within 180-230 min for studied samples. The adsorption kinetics of methylene blue was found to best be described by pseudo-second-order kinetic model. It was shown that dyes adsorption processes were well described by Freundlich model, which takes into consideration the heterogeneity of the surface of the adsorbent. The obtained plant sorbents are characterized by a high sorption capacity for heavy metal ions (18-29 mg/g for Fe3+ and 33-44 mg/g for Cu-2). Due to their numerous advantages, such as the high sorption capacity, high availability and low cost of raw materials, simplicity of disposal and nontoxicity, the obtained natural sorbents may have a wide practical use in industrial wastewater treatment. [GRAPHICS] .

  • 87.
    Hasani, Merima
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden.
    Gunnarsson, Maria
    Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden..
    Swensson, Beatrice
    Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden..
    Bernin, Diana
    Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden..
    Dissolution of cellulose in NaOH(aq): an unexpected chemisorption of CO2(g)2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 88.
    Hedlund, Artur
    et al.
    Swerea IVF, Biobased Fibers, Argongatan 30, S-43153 Molndal, Sweden.;Chalmers Univ Technol, Forest Prod & Chem Engn, Gothenburg, Sweden..
    Kohnke, Tobias
    Swerea IVF, Biobased Fibers, Argongatan 30, S-43153 Molndal, Sweden..
    Hagman, Joel
    Lund Univ, Phys Chem, Box 124, S-22100 Lund, Sweden..
    Olsson, Ulf
    Lund Univ, Phys Chem, Box 124, S-22100 Lund, Sweden..
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Forest Prod & Chem Engn, Gothenburg, Sweden.;Chalmers Univ Technol, .
    Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1545-1563Article in journal (Refereed)
    Abstract [en]

    Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water2PrOHbutanonecyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid-liquid versus liquid-liquid phase separations. [GRAPHICS] .

  • 89.
    Henschen, Jonatan
    et al.
    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.
    Larsson, Per
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Antibacterial surface modification of nanocellulosic materials2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 90.
    Herrera, Martha
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Thitiwutthisakul, Kasinee
    SCG Packaging Publ Co Ltd, Prod & Technol Dev Ctr, Ban Pong 70110, Ratchaburi, Thailand..
    Yang, Xuan
    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.
    Rujitanaroj, Pim-on
    SCG Packaging Publ Co Ltd, Prod & Technol Dev Ctr, Ban Pong 70110, Ratchaburi, Thailand..
    Rojas, Ramiro
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Preparation and evaluation of high-lignin content cellulose nanofibrils from eucalyptus pulp2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 5, p. 3121-3133Article in journal (Refereed)
    Abstract [en]

    High Klason lignin content (23 wt%) cellulose nanofibrils (LCNF) were successfully isolated from eucalyptus pulp through catalyzed chemical oxidation, followed by high-pressure homogenization. LCNFs had a diameter of ca. 13 nm according to AFM evaluation. Dense films were obtained through vacuum filtration (nanopaper) and subjected to different drying methods. When drying under heat and mild vacuum (93 degrees C, 95 kPa) a higher water contact angle, lower roughness and oxygen transmission rate were observed, compared to those drying at room temperature under compression conditions. DSC experiments showed difference in signals associated to T-g of LCNF compared to CNF produced from spruce bleached pulp through enzymatic pre-treatment. The LCNF-based nanopaper showed mechanical properties slightly lower than for those made from cellulose nanofibrils, yet with increased hydrophobicity. In summary, the high-lignin content cellulose nanofibrils proved to be a suitable material for the production of low oxygen permeability nanopaper, with chemical composition close to native wood.

  • 91.
    Hua, Yong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Liu, Peng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    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), Chemical Engineering.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells2018In: SOLAR RRL, ISSN 2367-198X, Vol. 2, no 5, article id UNSP 1700073Article in journal (Refereed)
    Abstract [en]

    Spiro-OMeTAD has been the most commonly used hole-transport material in perovskite solar cells. However, this material shows intrinisic drawbacks, such as low hole mobility and conductivity in its pristine form, as well as self-aggregation when deposited as thin film. These are not beneficial properties for efficient hole transport and extraction. In order to address these issues, we have designed a new type of composite hole-transport materials based on a new metal-organic copper complex (CuH) and Spiro-OMeTAD. The incorporation of the molecularly bulky HTM CuH into the Spiro-OMeTAD material efficiently improves the hole mobility and suppresses the aggregation in the Spiro-OMeTAD film. As a result, the conversion efficiencies obtained for perovskite solar cells based on the composite HTM system reached as high as 18.83%, which is superior to solar cells based on the individual hole-transport materials CuH (15.75%) or Spiro-OMeTAD (14.47%) under the same working conditions. These results show that composite HTM systems may constitute an effective strategy to further improve the efficiency of perovskite solar cells.

  • 92.
    Huang, Tianxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chen, Chao
    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.
    Li, Dongfang
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Stockholm, Sweden..
    Hydrophobic and antibacterial textile fibres prepared by covalently attaching betulin to cellulose2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 93.
    Ingverud, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Exploring crosslinked networks of polymers and hybrid cellulose materials2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The field of polymer chemistry has in recent decades had an immense development, resulting in new functional materials with groundbreaking applications. This has been driven partly by strong interdisciplinary alliances between the fields of medicine, biology, chemistry, and materials science. Thermoresponsive block copolymers, have been built for their ability to self-assemble, giving possibility of encapsulation and release of medicine. The dendritic polymer family have been demonstrated as a prime example of highly reactive and interactive functional materials, suitable for biomedical applications. The importance of amines is greatly appreciated in general and especially in polymer chemistry, due to their nucleophilic characteristics in reactions, but also for their ability to interact with other species. There’s also an increase in awareness of standard of living, the effects of climate change and population growth. These are challenges, in need of our outmost focus and knowledge, to direct our path to, towards a more bio based circular economy. This starts, in Sweden, by taking better care of our forest and utilizing its resourceful crop. This thesis seek out spontaneous crosslinking, of various functional polymers, with focus towards hybridizing with nanocellulosic material.

    Initially, interactive permanently charged amine-functional thermoresponsive tri- and star-block copolymers were composed. These were evaluated and used as electrostatic macro-crosslinker of cellulose nanofibrils (CNFs), resulting in thermoresponsive, low dry weight content hydrogels, with notable temperature dependent storage modulus.

    Secondly, reactive and interactive amine-functional dendritic-linear-dendritic (DLD) species were constructed and evaluated in vitro and in vivo. The DLD scaffolds were utilized as fast-degrading, inhibiting surgical site infection (SSIs) antibacterial hydrogel coatings. The crosslinking of the poly(ethylene glycol) (PEG) system was optimized in order to create a two component system, which could be applied with dual syringes. This enabled instantaneous gelation under physiological conditions. The hydrogels moduli could be varied to match various tissues.

    Thirdly, insights and characterizations were provided in the commercial heterofunctional poly(amido amine) carboxylate hyperbranched Helux. Amine post-modifications and intrinsic heterofunctionality alterations of Helux were explored, by increasing the molecular weight and forming Helux self-crosslinked films. Furthermore, two component hydrogels based on Helux and PEG demonstrated curing temperature dependent moduli in the rheometer.

    Finally, utilizing Helux in combination with CNFs to demonstrate the potential to mix on the nanoscale without aggregation. The CNF-Helux could form hydrogels, and wet-stable thermo-crosslinked CNF-Helux composites assemblies such as films and aerogels, with further excess of amines ready for post-modifications of the crosslinked 3D-network.

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  • 94.
    Ingverud, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Erlandsson, Johan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Malkoch, Michael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    The combination of a dendritic polyampholyte and cellulose nanofibrils – a new type of functional materialManuscript (preprint) (Other academic)
  • 95.
    Jawerth, Marcus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Institute of Technology.
    Thermoset resins using technical lignin as a base constituent2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The need to find sustainable paths for our society is imminent to tackle environmental concerns of today. The majority of all plastic materials are produced from crude oil but in the future a much larger portion must originate from renewable resources to address some of these problems. Aromatic molecules are often used when producing rigid and thermally stable polymeric materials but there are few natural sources for them. One is, however, the wood component lignin that is produced on a large scale from chemical pulping processes of biomass. Lignins aromatic structures could be an alternative for non-renewable aromatics in e.g. thermoset applications.

    The heterogeneity of lignin does however present some problems in terms of e.g. dispersity, solubility, diverse functionality, and varying polymer backbone structure. To tackle these challenges, work-up of lignin and thorough characterization are important to be able to produce materials with predetermined, predictable, properties. Technical lignins have functional groups that can be utilized as chemical handles for further modifications required for different material systems e.g. phenols, aliphatic hydroxyls, and carboxylic acids.

    This thesis focuses on how to utilize solvent fractionated, relatively well-characterized, LignoBoost Kraft lignin to produce thermoset resins by chemical modification and a crosslinking procedure. An efficient procedure to selectively allylate the phenolics, the most abundant functionality, of the lignin fractions has been developed and evaluated as well as a curing procedure using a thiol crosslinker and a thiol-ene reaction. The produced materials were analysed with regards to material properties, density, and morphology. The resins based on the selectively allylated lignin fractions were furthermore evaluated as a potential matrix for carbon fibre composites. It was shown that the material samples could be processed by pre-impregnating carbon fibres and form composite materials. The molecules of the lignin fraction were also used as core substrates in a ring-opening polymerization to produce functional star co-polymers. The procedure was evaluated and it could be shown that the lignin backbone was subjected to substantial structural changes of lignin inter-unit linkages.

    Lignin being one of the few large resources of naturally occurring aromatics has a big potential to be used for material applications where rigidity and thermal stability is important. This thesis attempts to add a few pieces towards such a goal.

    The full text will be freely available from 2020-06-01 09:38
  • 96.
    Jawerth, Marcus
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Brett, Calvin
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Terrier, Cedric
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Larsson, Per Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Lundmark, Stefan
    Perstorp AB, Innovat, S-28480 Perstorp, Sweden..
    Johansson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH Royal Inst Technol, Div Coating Technol, Dept Fibre & Polymer Technol, S-10044 Stockholm, Sweden..
    Mechanical and Morphological Properties of Lignin-Based Thermosets2020In: ACS APPLIED POLYMER MATERIALS, ISSN 2637-6105, Vol. 2, no 2, p. 668-676Article in journal (Refereed)
    Abstract [en]

    The need for renewable alternatives for fossil-based aromatic material constituents is evident for a more sustainable society. Lignin is the largest source of naturally occurring aromatic compounds but has mainly been considered as waste material or energy source in the pulp and paper industry. Developments in extracting lignin from these processes provide a large source for renewable aromatic structures to be used in various applications. Producing thermosets out of lignin is a very promising route to utilize this raw material toward, for example, composite application. The buildup of the molecular network based on oligomeric lignin segments will be different from traditional thermoset analogues, where the constituents often are smaller molecules, and will have an effect on the material properties. In this work LignoBoost Kraft lignin is refined, chemically modified, and used to produce freestanding thermosets with different architectures and properties. These different thermosets are evaluated, and the possibilities to tailor the material properties through work-up and modification are demonstrated. Morphological studies on the formed thermosets using X-ray scattering show systematic differences in molecular stacking and aggregate sizes.

  • 97.
    Jawerth, Marcus
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Johansson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Renewable thermosetting resins based on refined technical lignin: fractionation, modification and valorization2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 98. Juang, Yu-Pu
    et al.
    Lin, You-Yu
    Chan, She-Hung
    Chang, Chun-Kai
    Shie, Jiun-Jie
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Guh, Jih-Hwa
    Liang, Pi-Hui
    Synthesis, distribution analysis and mechanism studies of N-acyl glucosamine-bearing oleanolic saponins2020In: Bioorganic chemistry (Print), ISSN 0045-2068, Vol. 99, p. 103835-Article in journal (Refereed)
    Abstract [en]

    A series of N-acyl glucosamine-bearingtriterpenoidsaponins has been synthesized with cytotoxic activities evaluated against HL-60, PC-3, HCT-116, and CT-26 tumor cells. Saponins incorporated anoleanolic acid (OA) triterpenoidal core exhibited the highest cytotoxic activity. To study the influence of the lengths of acyl-carbon chain onN-position of glucosamine, cells were treated with28-propargylamides and then reacted with an azido-fluorogenic probe under CuAACclickreactions to visualize the intact distributions of these compounds by confocal microscopy and flow cytometry; it was found that cytotoxic-active compounds (30–32) located in the cytosol and inactivecompounds bearing longer carbon chains (33–35) were impenetrable across cell membranes.Our study demonstrated the defined lipophilic acyl-carbon chain length can precisely regulate thecytotoxic activityof saponins, which is useful for the future development of cytotoxic agents.Furthermore, using quantitative proteomics and immunolabeling,the mechanism ofcytotoxicity induced by the synthetic saponin after membrane penetration could be a result of activation of death receptor pathway and inhibition of PI3K/Akt/mTOR pathway.

  • 99.
    Jungstedt, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Solid Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    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.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Biofibre Materials Centre, BiMaC.
    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.
    Mechanical properties of transparent high strength biocomposites from delignified wood veneer2020In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) based on delignified birch veneer and thermoplastic poly(methyl methacrylate) (PMMA) is investigated by uniaxial tensile tests and full-field strain analyses based on digital image correlation techniques. TW is considered as a composite of unidirectional fibers (wood veneer) in a matrix (PMMA). Four in-plane elastic constants along the material axes are reported to enable the usage of continuum mechanics and lamination theory. Longitudinal composite strength is as high as 270 MPa at a reinforcement content of only 25 vol%. The failure behavior is interpreted based on strain field development. Strong reinforcement effects were observed from delignified birch veneer. Despite the fragility of delignified veneers, this constituent provides unexpectedly high reinforcement due to the high cellulose content and favorable stress transfer mechanisms.

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  • 100.
    Kaldéus, Tahani
    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, Coating Technology.
    Surface modification approaches of cellulose nanofibrils and their effect on dispersibility2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the strive to find and develop sustainable bio-based materials an increased interest for nanocellulosic materials as attractive alternatives has arisen during the past decades. This can be attributed to their abundant renewability, remarkable inherent mechanical properties and their capability to be chemically modified. Cellulose nanofibrils (CNFs) are commonly obtained from wood pulp fibres and prepared through mechanical, chemical and/or enzymatic treatments. However, due to their hydrophilic nature and tendency to self-aggregate, their surface chemistry need to be altered to fully utilise their inherent properties and enable their usage in conventional large-scale industrial processes.

    This thesis work focuses on elucidating the fundamental aspects of the colloidal stability of highly concentrated CNF dispersions and the redispersibility of dried CNFs. Small amounts of amine-terminated poly(ethylene glycol) (PEG) were used to sterically stabilise the CNFs at higher fibril concentrations and delay the dispersion-arrested state transition (Paper I). The redispersibility of dried CNFs was studied for differently charged CNFs as a function of redispersing agents such as carboxymethyl cellulose (CMC), PEG and lignin (Paper II).

    This thesis presents green, facile modification approaches as well as strategies for improved dispersibility and compatibility with polymer matrices. The commercially established carboxymethylation process was expanded with a subsequent functionality step, yielding a mild, versatile one-pot protocol for the preparation of bi-functional CNFs (Paper III). Further, reactive amphiphilic macromolecules with targeted side-chain functionalities were used to compatibilise the CNF surface by water-based approaches. In the first study, a macroinitiator was used for the development of a versatile, yet facile, protocol for the controlled polymerisation of both hydrophilic and hydrophobic monomers in water from the CNF surface (Paper IV). In the second study, a reactive macro-compatibiliser was used to molecularly engineer the interface between CNFs and a polymer matrix by reactive-melt processing, yielding nanocomposites with improved stiffness while maintaining the deformability (Paper V).

    The full text will be freely available from 2020-12-31 11:00
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