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  • 51. Fang, Wenwen
    et al.
    Paananen, Arja
    Vitikainen, Marika
    Koskela, Salla
    VTT Technical Research Centre of Finland Ltd.
    Westerholm-Parvinen, Ann
    Joensuu, Jussi
    Landowski, Christopher
    Penttilä, Merja
    Linder, Markus
    Laaksonen, Päivi
    Elastic and pH responsive hybrid interfaces created with engineered resilin and nanocellulose2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 6, p. 1866-1873Article in journal (Refereed)
    Abstract [en]

    We investigated how a genetically engineered resilin fusion protein modifies cellulose surfaces. We characterized the pH-responsive behavior of a resilin-like polypeptide (RLP) having terminal cellulose binding modules (CBM) and showed its binding to cellulose nanofibrils (CNF). Characterization of the resilin fusion protein at different pHs revealed substantial conformational changes of the protein, which were observed as swelling and contraction of the protein layer bound to the nanocellulose surface. In addition, we showed that employment of the modified resilin in cellulose hydrogel and nanopaper increased their modulus of stiffness through a cross-linking effect.

  • 52.
    Farahani, Saina Kishani
    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.
    Escalante, Alfredo
    Toriz, Guillermo
    Vilaplana, Francisco
    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.
    Gatenholm, Paul
    Hansson, Per
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Experimental and Theoretical Evaluation of the Solubility/Insolubility Spruce Xylan (Arabino Glucuronoxylan)2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1263-1270Article in journal (Refereed)
    Abstract [en]

    The molecular solubility of softwood arabinoglucuronoxylan (AGX) has been thoroughly investigated, and it has been shown that the chemical and physical structures of the extracted hemicellulose are not significantly influenced by different purification steps, but a transient molecular solubility of AGX was observed in aqueous media at low concentrations (1 g/L) when the dissolved macromolecules had a hydrodynamic diameter of up to 10 nm. A phase separation was detected when the concentration was increased to 15 g/L leading to an association of the smaller molecules into fractal structures with a considerably larger diameter, even though the dispersions were still transparent to ocular inspection. Dynamic Light Scattering and Cryo-Transmission Electron Microscopy showed dimensions in the range of 1000 nm. The phase separation of the sample was further characterized by estimating the χ-interaction parameter of AGX in water using the Flory-Huggins theory, and the results supported that water is a poor solvent for AGX. This behavior is crucial when films and hydrogels based on these biopolymers are made, since the association will dramatically affect barrier and mechanical properties of films made from these materials.

  • 53.
    Feng, Zhaoxuan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Takahiro, Danjo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Tadahisa, Iwata
    Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo.
    Albertsson, Ann-Christine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Recyclable fully biobased chitosan adsorbents spray-dried in one-pot to microscopic size and enhanced adsorption capacity2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 5, p. 1956-1964Article in journal (Refereed)
    Abstract [en]

    A facile one-pot spray-drying process was developed for fabrication and in-situ crosslinking of chitosan microspheres to improve the adsorption capacity by microscopic design. A fully biobased nature was achieved by utilizing genipin (GP) as a crosslinking agent and chitosan derived nano-graphene oxide (nGO) as a property tuner. The produced chitosan microspheres were further proven as powerful adsorbents for common wastewater contaminants such as anionic dyes and pharmaceutical contaminants, here modelled by methyl orange (MO) and diclofenac sodium (DCF). By regulating the amount of GP and nGO, as well as by controlling the process parameters including the spraydrying inlet temperature and post-heat treatment, the surface morphology, size, zeta potential and adsorption efficiency of the microspheres could be tuned accordingly. The adsorption efficiency for MO and DCF reached 98.9 and 100 %, respectively. The microspheres retained high DCF adsorption efficiency after six adsorption and desorption cycles and the recyclability was improved by incorporated nGO. The fabricated microspheres, thus, have great potential as reusable and eco-friendly adsorbents.

  • 54. Filonova, Lada
    et al.
    Kallas, Åsa M.
    KTH, School of Biotechnology (BIO).
    Greffe, Lionel
    KTH, School of Biotechnology (BIO).
    Teeri, Tuula T.
    Daniel, Geoffrey
    Johansson, Gunnar
    Mapping of crystalline cellulose and mannan on the surfaces of wood tissues and pulp fibers using carbohydrate binding modules2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 1, p. 91-97Article in journal (Refereed)
    Abstract [en]

    Carbohydrate binding modules (CBMs) are noncatalytic substrate binding domains of many enzymes involved in carbohydrate metabolism. Here we used fluorescent labeled recombinant CBMs specific for crystalline cellulose (CBM1(HjCel7A)) and mannans (CBM27(TmMan5) and CBM35(CjMan5C)) to analyze the complex surfaces of wood tissues and pulp fibers. The crystalline cellulose CBM1(HjCel7A) was found as a reliable marker of both bacterially produced and plant G-layer cellulose, and labeling of spruce pulp fibers with CBM1(HjCel7A) revealed a signal that increased with degree of fiber damage. The mannan-specific CBM27(TmMan5) and CBM35(CjMan5C) CBMs were found to be more specific reagents than a monoclonal antibody specific for (1 -> 4)-beta-mannan/galacto-(1 -> 4)-beta-mannan for mapping carbohydrates on native substrates. We have developed a quantitative fluorometric method for analysis of crystalline cellulose accumulation on fiber surfaces and shown a quantitative difference in crystalline cellulose binding sites in differently processed pulp fibers. Our results indicated that CBMs provide useful, novel tools for monitoring changes in carbohydrate content of nonuniform substrate surfaces, for example, during wood or pulping processes and possibly fiber biosynthesis.

  • 55.
    Finne, Anna
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Controlled synthesis of star-shaped L-lactide polymers using new spirocyclic tin initiators2002In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 4, p. 684-690Article in journal (Refereed)
    Abstract [en]

    The reaction between pentaerythritol ethoxylate compounds and dibutyltin oxide was developed as a route to synthesize two new spirocyclic tin initiators. The initiators were successfully synthesized and they were characterized by H-1 NMR and differential scanning calorimetry (DSC). The H-1 NMR spectra showed the characteristic signals for the methylene protons in the ether chains. Furthermore, the usefulness of the new initiators was examined in ring-opening polymerizations of L-lactide in chloroform at 60 degreesC. L-Lactide was polymerized at monomer-to-initiator ([M]/[I]) ratios between 20 and 500. The results indicated that the initiation was instantaneous and that the molecular weight distribution was very narrow, <1.13, The number average molecular weight could be controlled by the [M]/[I] ratio, and the yield was very high. H-1 NMR, size exclusion chromatography, and DSC were used to clarify the architecture, The expected results were obtained. The star-shaped polymers had a smaller hydrodynamic volume, and the melting point was lower than that obtained for the corresponding linear poly(L-lactide).

  • 56.
    Finne, Anna
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Andronova, Natalia
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Well-organized phase-separated nanostructured surfaces of hydrophilic/hydrophobic ABA triblock copolymers2003In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 4, no 5, p. 1451-1456Article in journal (Refereed)
  • 57.
    Fuoco, Tiziana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enhancing the Properties of Poly(epsilon-caprolactone) by Simple and Effective Random Copolymerization of epsilon-Caprolactone with p-Dioxanone2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 8, p. 3171-3180Article in journal (Refereed)
    Abstract [en]

    We have developed a straightforward strategy to obtain semicrystalline and random copolymers of epsilon-caprolactone (CL) and p-dioxanone (DX) with thermal stabilities similar to poly(epsilon-caprolactone), PCL, but with a faster- hydrolytic degradation rate-CL/DX-copolymers-are promising inks when printing scaffolds aimed for tissue engineering. Such copolymers behave similar to PCL and resorb faster. The copolymers were synthesized by bulk ring-opening copolymerization, achieving a high yield; a molecular weight, M-n, of 57-176 kg mol(-1); and an inherent viscosity of 1.7-1.9 dL g(-1). The copolymer microstructure consisted of long CL blocks that are separated by isolated DX units. The block length and the melting point were a linear function of the DX content. The copolymers crystallize as an orthorhombic lattice that is typical for PCL, and they formed more elastic, softer, and less hydrophobic films with faster degradation rates than PCL. Relatively high thermal degradation temperatures (above 250 C), similar to PCL, were estimated by thermogravimetric analysis, and copolymer filaments for three-dimensional printing and scaffolds were produced without thermal degradation.

  • 58.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Salerno, Italy.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Sannio, Italy.
    A Route to Aliphatic Poly(ester)s with Thiol Pendant Groups: From Monomer Design to Editable Porous Scaffolds2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 4, p. 1383-1394Article in journal (Refereed)
    Abstract [en]

    Biodegradable aliphatic polyesters such as poly(lactide) and poly(ϵ-caprolactone), largely used in tissue engineering applications, lack suitable functional groups and biological cues to enable interactions with cells. Because of the ubiquity of thiol groups in the biological environment and the pliability of thiol chemistry, we aimed to design and synthesize poly(ester) chains bearing pendant thiol-protected groups. To achieve this, 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a lactide-type monomer possessing a pendant thiol-protected group, was synthesized. This molecule, when used as a monomer in controlled ring-opening polymerization in combination with lactide and ϵ-caprolactone, appeared to be a convenient "building block" for the preparation of functionalized aliphatic copolyesters, which were easily modified further. A polymeric sample bearing pyridyl disulfide groups, able to bind a cysteine-containing peptide, was efficiently obtained from a two-step modification reaction. Porous scaffolds were then prepared by blending this latter copolymer sample with poly(l-lactide-co-ϵ-caprolactone) followed by salt leaching. A further disulfide exchange reaction performed in aqueous medium formed porous scaffolds with covalently linked arginine-glycine-aspartic acid sequences. The scaffolds were characterized by thermal and mechanical tests, and scanning electron microscopy surface images revealed a highly porous morphology. Moreover, a cytotoxicity test indicated good cell viability.

  • 59.
    Fuoco, Tiziana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mathisen, Torbjorn
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Poly(L-lactide) and Poly(L-lactide-co-trimethylene carbonate) Melt-Spun Fibers: Structure-Processing-Properties Relationship2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1346-1361Article in journal (Refereed)
    Abstract [en]

    l-Lactide/trimethylene carbonate copolymers have been produced as multifilament fibers by high-speed melt-spinning. The relationship existing between the composition, processing parameters and physical properties of the fibers has been disclosed by analyzing how the industrial process induced changes at the macromolecular level, i.e., the chain microstructure and crystallinity development. A poly(l-lactide) and three copolymers having trimethylene carbonate contents of 5, 10 and 18 mol % were synthesized with high molecular weight (M n ) up to 377 kDa and narrow dispersity. Their microstructure, crystallinity and thermal properties were dictated by the composition. The spinnability was then assessed for all the as-polymerized materials: four melt-spun multifilament fibers with increasing linear density were collected for each (co)polymer at a fixed take-up speed of 1800 m min -1 varying the mass throughput during the extrusion. A linear correlation resulted between the as-spun fiber properties and the linear density. The as-spun fibers could be further oriented, developing more crystallinity and improving their tensile properties by a second stage of hot-drawing. This ability was dependent on the composition and crystallinity achieved during the melt-spinning and the parameters selected for the hot-drawing, such as temperature, draw ratio and input speed. The crystalline structure evolved to a more stable form, and the degree of crystallinity increased from 0-52% to 25-66%. Values of tensile strength and Young's modulus up to 0.32-0.61 GPa and 4.9-8.4 GPa were respectively achieved.

  • 60.
    Galland, Sylvian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berthold, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Innventia AB, Sweden.
    Prakobna, Kasinee
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Holocellulose nanofibers of high molar mass and small diameter for high-strength nanopaper2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 8, p. 2427-2435Article in journal (Refereed)
    Abstract [en]

    Wood cellulose nanofibers (CNFs) based on bleached pulp are different from the cellulose microfibrils in the plant cell wall in terms of larger diameter, lower cellulose molar mass, and modified cellulose topochemistry. Also, CNF isolation often requires high-energy mechanical disintegration. Here, a new type of CNFs is reported based on a mild peracetic acid delignification process for spruce and aspen fibers, followed by low-energy mechanical disintegration. Resulting CNFs are characterized with respect to geometry (AFM, TEM), molar mass (SEC), and polysaccharide composition. Cellulose nanopaper films are prepared by filtration and characterized by UV-vis spectrometry for optical transparency and uniaxial tensile tests. These CNFs are unique in terms of high molar mass and cellulose-hemicellulose core-shell structure. Furthermore, the corresponding nanopaper structures exhibit exceptionally high optical transparency and the highest mechanical properties reported for comparable CNF nanopaper structures.

  • 61. Gallstedt, M.
    et al.
    Mattozzi, Alessandro
    KTH, Superseded Departments, Polymer Technology.
    Johansson, E.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments, Polymer Technology.
    Transport and tensile properties of compression-molded wheat gluten films2004In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 5, no 5, p. 2020-2028Article in journal (Refereed)
    Abstract [en]

    Mechanical and transport properties were assessed on wheat gluten films with a glycerol content of 25-40%, prepared by compression molding for 5-15 min at temperatures between 90 and 130 degreesC. Effects of storing the films up to 24 days, in 0 and 50% relative humidity (RH), were assessed by tensile measurements. The films were analyzed with respect to methanol zero-concentration diffusivity, oxygen permeability (OP), water vapor permeability (WVP), Cobb(60) and sodium dodecyl sulfate (SDS) solubility coupled with sonication. The SDS solubility and methanol diffusivity were lower at the higher molding temperature. Higher glycerol content resulted in higher OP (90-95% RH), WVP, and Cobb(60) values, due to the plasticizing and hygroscopic effects. Higher glycerol contents gave a lower fracture stress, lower Young's modulus, lower fracture strain, and less strain hardening. The mold time had less effect on the mechanical properties than mold temperature and glycerol content. The fracture stress and Young's modulus increased and the fracture strain decreased with decreasing moisture content.

  • 62.
    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.

  • 63.
    Ghanadpour, Maryam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Carosio, Federico
    Larsson, Per Tomas
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Phosphorylated Cellulose Nanofibrils: A Renewable Nanomaterial for the Preparation of Intrinsically Flame-Retardant Materials2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 10, p. 3399-3410Article in journal (Refereed)
    Abstract [en]

    Cellulose from wood fibers can be modified for use in flame-retardant composites as an alternative to halogen-based compounds. For this purpose, sulfite dissolving pulp fibers have been chemically modified by phosphorylation, and the resulting material has been used to prepare cellulose nanofibrils (CNF) that have a width of approximately 3 nm. The phosphorylation was achieved using (NH4)(2)HPO4 in the presence of urea, and the degree of substitution by phosphorus was determined by X-ray photoelectron spectroscopy, conductometric titration, and nuclear magnetic resonance spectroscopy. The presence of phosphate groups in the structure of CNF has been found to noticeably improve the flame retardancy of this material. The nanopaper sheets prepared from phosphorylated CNF showed self-extinguishing properties after consecutive applications of a methane flame for 3 s and did not ignite under a heat flux of 35 kW/m(2), as shown by flammability and cone calorimetry measurements, respectively.

  • 64.
    Gicquel, Erwan
    et al.
    Univ Grenoble Alpes, CNRS, Grenoble INP, LGP2, F-38000 Grenoble, France..
    Martin, Caine
    Univ Grenoble Alpes, CNRS, Grenoble INP, LGP2, F-38000 Grenoble, France..
    Gauthier, Quentin
    Univ Grenoble Alpes, CNRS, Grenoble INP, LGP2, F-38000 Grenoble, France..
    Engström, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Abbattista, Clara
    Univ Grenoble Alpes, CNRS, Grenoble INP, LGP2, F-38000 Grenoble, France..
    Carlmark, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cranston, Emily D.
    Univ British Columbia, Dept Chem & Biol Engn, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada.;Univ British Columbia, Dept Wood Sci, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada..
    Jean, Bruno
    Univ Grenoble Alpes, CNRS, CERMAV, F-38000 Grenoble, France..
    Bras, Julien
    Univ Grenoble Alpes, CNRS, Grenoble INP, LGP2, F-38000 Grenoble, France.;Inst Univ France, F-75000 Paris, France..
    Tailoring Rheological Properties of Thermoresponsive Hydrogels through Block Copolymer Adsorption to Cellulose Nanocrystals2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 7, p. 2545-2556Article in journal (Refereed)
    Abstract [en]

    This study investigates the adsorption of a block copolymer composed of a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) cationic polyelectrolyte and a poly(di(ethylene glycol) methyl ethermethacrylate) (PDEGMA) on oxidized cellulose nanocrystals (TO-CNCs) to produce hydrogels. PDMEAMA-b-PDEGMA was synthesized by atom-transfer radical polymerization. The extent and dynamics of the adsorption of PDMAEMA-b-PDEGMA on TO-CNCs were determined by electromechanical microbalance and optical techniques. Electrostatic adsorption was identified on TO-CNCs with the quaternized block copolymer. Small-angle neutron scattering experiments were performed to investigate the polymer behavior on the TO-CNC surfaces. Depending on the temperature, block copolymer induces the aggregation of nanocrystals after adsorption by connecting CNCs bundles with block copolymer chains. A reversible liquid-to-gel transition, triggered by temperature, was clearly detected by rheological measurements for the copolymer-CNC mixtures. At the optimal copolymer to CNC ratio the viscosity increased by 4 orders of magnitude at low shear rates. These stimuli-responsive CNC-based materials could be used as injectable biomedical systems.

  • 65.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Simultaneous Polymerization and Polypeptide Particle Production via Reactive Spray-Drying2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 9, p. 2930-2936Article in journal (Refereed)
    Abstract [en]

    A method for producing polypeptide particles via in situ polymerization of N-carboxyanhydrides during spray-drying has been developed. This method was enabled by the development of a fast and robust synthetic pathway to polypeptides using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an initiator for the ring-opening polymerization of N-carboxyanhydrides. The polymerizations finished within 5 s and proved to be very tolerant toward impurities such as amino acid salts and water. The formed particles were prepared by mixing the monomer, N-carboxyanhydride of L-glutamic acid benzyl ester (NCA(Glu)) and the initiator (DBU) during the atomization process in the spray-dryer and were spherical with a size of similar to 1 um. This method combines two steps; making it a straightforward process that facilitates the production of polypeptide particles. Hence, it furthers the use of spray-drying and polypeptide particles in the pharmaceutical industry.

  • 66.
    Glavas, Lidija
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Olsén, Peter
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Achieving Micelle Control through Core Crystallinity2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 11, p. 4150-4156Article in journal (Refereed)
    Abstract [en]

    We have designed a pathway for controlling the critical micelle concentration and micelle size of polyester-based systems. This was achieved by creating an array of different copolymers with semicrystalline or amorphous hydrophobic blocks. The hydrophobic block was constructed through ring-opening polymerization of epsilon-caprolactone, L-lactide, and epsilon-decalactone, either as homopolymers or random copolymers, using PEG as both the initiator and the hydrophilic block. Micelles formed with amorphous cores exhibited considerably higher critical micelle concentrations than those with semicrystalline cores. Micelles with amorphous cores also became larger in size with an increased molecular weight of the hydrophobic bock, in contrast to micelles with semicrystalline cores, which displayed the opposite behavior. Hence, core crystallinity was found to be a potent tool for tailoring micelle properties and thereby facilitating the optimization of drug delivery systems. The introduction of PEG-P epsilon DL also proved to be a valuable asset in the tuning of micelle properties.

  • 67.
    Gullfot, Fredrika
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Ibatullin, Farid
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sundqvist, Gustav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Davies, Gideon
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Functional Characterization of Xyloglucan Glycosynthases from GH7, GH12, and GH16 Scaffolds2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 7, p. 1782-1788Article in journal (Refereed)
    Abstract [en]

    Glycosynthases, hydrolytically inactive mutant glycosidases that catalyze glycosylation reactions using glycosyl fluoride donor substrates, are emerging as useful tools for the synthesis of large, complex polysaccharides [Faijes, M.; Planas, A. Carbohydr. Res. 2007, 342, 1581-1594]. Guided by wild-type xyloglucanase activity, we have produced and characterized new glycosynthases for the synthesis of xyloglucan oligo- and polysaccharides, based on family GH7, GH12, and GH16 scaffolds. The Humicola insolens GH7 glycosynthase, HiCel7B E197S, is capable of synthesizing nongalactosylated, XXXG-based homoxyloglucan up to Mw 60000 [G = Glcβ(1→4); X = Xylα(1→6)Glcβ(1→4); L = Galβ(1→2)Xylα(1→6)Glcβ(1→4)], which is among the largest products so far obtained with glycosynthase technology. Novel glycosynthases based on the GH16 xyloglucan hydrolase from Tropaeolum majus (nasturtium), TmNXG1, are capable of synthesizing XLLG-based xyloglucan oligosaccharides at rates feasible for preparative synthesis, thus providing an essential expansion of product range. Finally, a new glycosynthase based on the recently characterized GH12 xyloglucanase from Bacillus licheniformis, BlXG12 E155A, can perform the condensation of xyloglucosyl fluorides, albeit at poor rates. Altogether, the high catalytic efficiency demonstrated by HiCel7B E197S and the extended product range provided by TmNXG1 E94A are key achievements toward a robust and versatile method for the preparative synthesis of homogeneous xyloglucans with regular substitution patterns not available in nature. Such compounds enable in vitro experimental studies regarding the role of particular structural elements for xyloglucan properties and its interaction with cellulose.

  • 68.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Facile Synthesis of Degradable and Electrically Conductive Polysaccharide Hydrogels2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 7, p. 2601-2609Article in journal (Refereed)
    Abstract [en]

    Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and crosslinker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery.

  • 69.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Molecular Achitecture of electroactive and biodegradable copolymers composed of polyactide and carboxyl-capped aniline trimer2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, p. 855-863Article in journal (Refereed)
    Abstract [en]

    wo-, four-, and six-armed branched copolymers with electroactive and biodegradable properties were synthesized by coupling reactions between poly(l-lactides) (PLLAs) with different architecture and carboxyl-capped aniline trimer (CCAT). The aniline oligomer CCAT was prepared from amino-capped aniline trimer and succinic anhydride. FT-IR, NMR, and SEC analyses confirmed the structure of the branched copolymers. UV−vis spectra and cyclic voltammetry of CCAT and copolymer solution showed good electroactive properties, similar to those of polyaniline. The water contact angle of the PLLAs was the highest, followed by the undoped copolymer and the doped copolymers. The values of doped four-armed copolymers were 54−63°. Thermal properties of the polymers were studied by DSC and TGA. The copolymers had better thermal stability than the pure PLLAs, and the Tg between 48−58 °C and Tm between 146−177 °C of the copolymers were lower than those of the pure PLLA counterparts. This kind of electroactive and biodegradable copolymer has a great potential for applications in cardiovascular or neuronal tissue engineering.

  • 70.
    Gustafsson, Emil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johansson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Direct Adhesive Measurements between Wood Biopolyrner Model Surfaces2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 10, p. 3046-3053Article in journal (Refereed)
    Abstract [en]

    For the first time the dry adhesion was measured for an all-wood biopolymer system using Johnson-Kendall-Roberts (JKR) contact mechanics. The polydimethylsiloxane hemisphere was successfully surface-modified with a Cellulose I model surface using layer-by-layer assembly of nanofibrillated cellulose and polyethyleneimine. Flat surfaces of cellulose were equally prepared on silicon dioxide substrates, and model surfaces of glucomannan and lignin were prepared on silicon dioxide using spin-coating. The measured work of adhesion on loading and the adhesion hysteresis was found to be very similar between cellulose and all three wood polymers, suggesting that the interaction between these biopolymers do not differ greatly. Surface energy calculations from contact angle measurements indicated similar dispersive surface energy components for the model surfaces. The dispersive component was dominating the surface energy for all surfaces. The JKR work of adhesion was lower than that calculated from contact angle measurements, which partially can be ascribed to surface roughness of the model surfaces and overestimation of the surface energies from contact angle determinations.

  • 71. Gustavsson, M. T.
    et al.
    Persson, P. V.
    Iversen, T.
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Modification of cellulose fiber surfaces by use of a lipase and a xyloglucan endotransglycosylase2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 1, p. 196-203Article in journal (Refereed)
    Abstract [en]

    A strategy for the modification of cellulose fiber surfaces was developed that used the ability of Candida antarctica lipase B (CALB) to acylate carbohydrates with high regioselectivity, combined with the transglycosylating activity of the Populus tremula x P. tremuloides xyloglucan endotransglycosylase 16A (PttXET16A). Xyloglucan oligosaccharides (XGOs) prepared from tamarind xyloglucan were acylated with CALB as a catalyst and vinyl stearate or gamma-thiobutyrolactone as acyl donors to produce carbohydrate molecules with hydrophobic alkyl chains or reactive sulfhydryl groups, respectively. The modified XGOs were shown to act as glycosyl acceptors in the transglycosylation reaction catalyzed by PttXET16A and could therefore be incorporated into high M-r xyloglucan chains. The resulting xyloglucan molecules exhibited a high affinity for cellulose surfaces, which enabled the essentially irreversible introduction of fatty acid esters or thiol groups to cellulose fibers.

  • 72.
    Gustavsson, Malin T.
    et al.
    KTH, Superseded Departments, Biotechnology.
    Persson, P. V.
    Iversen, T.
    Hult, Karl
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Martinelle, Mats
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Polyester coating of cellulose fiber surfaces catalyzed by a cellulose-binding module-Candida antarctica lipase B fusion protein2004In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 5, no 1, p. 106-112Article in journal (Refereed)
    Abstract [en]

    A new approach to introduce polymers to cellulosic materials was developed by using the ability of a cellulose-binding module-Candida antarctica lipase B conjugate to catalyze ring-opening polymerization of epsilon-caprolactone in close proximity to cellulose fiber surfaces. The epsilon-caprolactone was introduced to the cellulose surfaces either by simple addition of liquid monomer or through gas phase. The effects of water activity and temperature on the lipase-catalyzed polymerization process were investigated. Analysis showed that the water content in the system primarily regulated the obtained polymer molecular weight, whereas the temperature influenced the reaction rate. The hydrophobicity of the obtained surfaces did not arise from covalent attachment of the poly(epsilon-caprolactone) to the surface hydroxyl groups but rather from surface-deposited polymers which could be readily extracted. The degree of lipase-catalyzed hydrolysis through introduction of water to the polymer-coated cellulose fiber surfaces was also investigated and shown to be significant.

  • 73. Haider, N.
    et al.
    Karlsson, Sigbritt
    KTH, Superseded Departments, Polymer Technology.
    Kinetics of migration of antioxidants from polyolefins in natural environments as a basis for bioconversion studies2000In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 1, no 3, p. 481-487Article in journal (Refereed)
    Abstract [en]

    Plastics ending up in soil or landfill environment will eventually be degraded. At the same time a slow migration of additives from the plastics will occur. The additives and the degradation products of these and the polymer are potential compounds for bioconversion. To predict the rate of the migration of antioxidants from polyolefins, a medium-density polyethylene film MDPE containing two commercial antioxidants, Irganox 1010 and Irgafos 168, was exposed to simulated landfill environments, viz. aqueous media at pH 5 and 7, with temperatures of 25, 50, 80, and 105 degreesC and solid-to-liquid ratios of 1:5. The migration process of the antioxidants was studied by an ultrasonic extraction technique using chloroform as extraction solvent to recover the nonmigrated antioxidants from the polymeric matrix, followed by quantitative analysis of the extracted antioxidants by high performance liquid chromatography (HPLC) with acetonitrile as the mobile phase and a wavelength of 280 nm. It was found that the release of both Irganox 1010 and Irgafos 168 increases at higher temperature, longer time, and lower pH. Moreover, the migration of Irgafos 168 proceeds faster than that of Irganox 1010 at lower temperatures while at higher temperatures the opposite behavior was observed. No degradation of the polymeric matrix was detected under the testing time. Migration processes included diffusion of the antioxidants within the polymer and their desorption from the surface of the polymer into the boundary layers of leachate. In general, the kinetic of the migration process was well described by first-order equations while an Arrhenius-type relationship was applicable for the temperature dependence of the constants. The general constants calculated for the migration processes were applied to the prediction of the time required for complete release of the antioxidants under different landfill conditions.

  • 74.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Indicator products: A new tool for lifetime prediction of polymeric materials2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 2, p. 775-779Article in journal (Refereed)
    Abstract [en]

    The possible correlation between the degree of degradation in the polymer matrix and the release of indicator products was investigated. The degree of degradation was measured by following the molar mass changes by size exclusion chromatography, while indicator products were analyzed by gas chromatography -mass spectrometry. The degree of degradation in polyethylene and polyethylene vinyl acetate matrix after thermooxidation was found to be in correlation with the amount of dicarboxylic acids and lactones formed during aging, while the degree of degradation in photooxidized polyethylene could be predicted from the amount of dicarboxylic acids. The relative amount of lactones compared to the relative amount of dicarboxylic acids increased if the oxidation temperature was increased. However, the total amount of indicator products was in correlation with the remaining number average molar mass and the number of chain scissions caused by oxidation. The amount of butanedioic acid and butyrolactone correlated well with the total amount of dicarboxylic acids and lactones, respectively. Thus, instead of the whole compound classes, butanedioic acid or butyrolactone alone could be used as indicators of oxidation. The detected correlation offers a novel tool for making lifetime predictions and studying the long-term properties of polymeric materials.

  • 75.
    Hansson, Susanne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Trouillet, Vanessa
    KIT Institute for Applied Materials (IAM-ESS).
    Tischer, Thomas
    KIT Institut für Technische Chemie und Polymerchemie.
    Goldmann, Anja
    KIT Institut für Technische Chemie und Polymerchemie.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Barner-Kowollik, Christopher
    KIT Institut für Technische Chemie und Polymerchemie.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Grafting Efficiency of Synthetic Polymers onto Biomaterials: A comparative study of grafting- from versus grafting- to2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 1, p. 64-74Article in journal (Refereed)
    Abstract [en]

    In the present study, the two grafting techniques grafting-from - by activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) - and grafting-to - by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) - were systematically compared, employing cellulose as a substrate. In order to obtain a meaningful comparison, it is crucial that the graft lengths of the polymers that are grafted from and to the substrates are essentially identical. Herein, this was achieved by utilizing the free polymer formed in parallel to the grafting-from reaction as the polymer for the grafting-to reaction. Four graft lengths were investigated, and the molar masses of the four free polymers (21 ≤ Mn ≤ 100 kDa; 1.07 ≤ M ≤ 1.26), i.e. the polymers subsequently employed in the grafting-to reaction, were shown to be in the same range as the molar masses of the polymers grafted from the surface (23 ≤ Mn ≤ 87 kDa; 1.08 ≤ M ≤ 1.31). The molecular weights of the chains grafted from the surface were established after cleavage from the cellulose substrates via size exclusion chromatography (SEC). High-resolution Fourier transform infrared microscopy (FT-IRM) was employed as an efficient tool to study the spatial distribution of the polymer content on the grafted substrates. In addition, the functionalized substrates were analyzed by X-ray photoelectron spectroscopy (XPS), contact angle (CA) measurements, and field-emission scanning electron microscopy (FE-SEM). For cellulose substrates modified via the grafting-from approach, the content of polymer on the surfaces increased with increasing graft length, confirming the possibility to tailor not only the length of the polymer grafts but also the polymeric content on the surface. In comparison, for the grafting-to reaction, the grafted content could not be controlled by varying the length of the preformed polymer: the polymer content was essentially the same for the four graft lengths. Consequently, the obtained results, when employing cellulose as a substrate and under these conditions, suggest that the grafting-from approach is superior to the grafting-to technique with respect to controlling the distribution of the polymeric content on the surface.

  • 76. Harrisson, Simon
    et al.
    Drisko, Glenna L.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Wooley, Karen L.
    Hybrid Rigid/Soft and Biologic/Synthetic Materials: Polymers Grafted onto Cellulose Microcrystals2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 4, p. 1214-1223Article in journal (Refereed)
    Abstract [en]

    Rigid nanoscale polymer rods were prepared by grafting preformed amine-terminated poly(styrene) and poly(tert-butyl acrylate) onto oxidized cellulose microcrystals. Low polydispersity polymers, grown using atom transfer radical polymerization, were characterized and purified prior to cellulose attachment. Oxidation of the cellulose microcrystal led to the formation of carboxylic acids on the surface of the microcrystals. Covalent attachment of the polymers onto the cellulose microcrystals was achieved via a carbodiimide-mediated amidation reaction. The length and diameter of the polymer-cellulose composites increased upon surface modification. Typically, polymer-cellulose composites are synthesized by a grafting-from method because it can be difficult to obtain sufficient graft density using a grafting-to preparation. However, the composites reported here comprised 60-64% grafted polymer by mass. This degree of grafting-to allowed the composite to form stable suspensions in organic solvents.

  • 77.
    Hartman, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sjöberg, John
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Surface- and bulk-modified galactoglucomannan hemicellulose films and film laminates for versatile oxygen barriers2006In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 7, no 6, p. 1983-1989Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to create oxygen barrier films based on the hemicellulose O-acetylgalactoglucomannan (AcGGM) that show high resistance toward moisture-rich conditions. We have applied Williamson benzylation, a classic derivatization method of carbohydrates, as well as two different methods for surface grafting, and, finally, lamination of unmodified hemicellulose films with the synthesized hydrophobic benzylgalactoglucomannan (BnGGM). It was found that the thermoplastically behaving BnGGM could form independent transparent and strong films that were easy to handle. As expected, their resistance toward water was very high, and the oxygen barrier properties showed drastically lower sensitivity toward moisture than films from the corresponding unmodified material. The surface grafting and lamination methods were approached in order to try and combine excellent barrier properties with moisture tolerance. It was found that the grafting methods applied had a positive effect in this direction; however, lamination turned out to be an even more promising option.

  • 78.
    Hassanzadeh, Salman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Adolfsson, Karin H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wu, Duo
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Supramolecular Assembly of Biobased Graphene Oxide Quantum Dots Controls the Morphology of and Induces Mineralization on Poly(epsilon-caprolactone) Films2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 1, p. 256-261Article in journal (Refereed)
    Abstract [en]

    Biobased 2D graphene oxide quantum dots (GOQDs) were synthesized from waste paper via carbon nanosphere intermediates and evaluated as property-enhancing additives for poly(epsilon-caprolactone) (PCL). The morphology of PCL films was controlled by supramolecular assembly of the small, 2D GOQDs in the polymer matrix. Phase behavior studies of PCL-GOQD in the solid state indicated concentration-dependent self-association of GOQD sheets, which was confirmed by SEM observations. Depending on the GOQD concentration, the formation of, e.g., spheres and stacked sheets was observed. GOQDs also induced mineralization on the surface of the films. A calcium phosphate (CaP) mineralization test revealed that the density of growing CaP crystals was controlled by the type of GOQD aggregates formed. Thus, utilization of the aggregation behavior of small GOQD sheets in polymeric matrices paves the way for tuning the morphology and properties of nanocomposites.

  • 79.
    Hatton, Fiona L.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ruda, M.
    Lansalot, M.
    D'Agosto, F.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Xyloglucan-Functional Latex Particles via RAFT-Mediated Emulsion Polymerization for the Biomimetic Modification of Cellulose2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 4, p. 1414-1424Article in journal (Refereed)
    Abstract [en]

    Herein, we report a novel class of latex particles composed of a hemicellulose, xyloglucan (XG), and poly(methyl methacrylate) (PMMA), specially designed to enable a biomimetic modification of cellulose. The formation of the latex particles was achieved utilizing reversible addition-fragmentation chain transfer (RAFT) mediated surfactant-free emulsion polymerization employing XG as a hydrophilic macromolecular RAFT agent (macroRAFT). In an initial step, XG was functionalized at the reducing chain end to bear a dithioester. This XG macroRAFT was subsequently utilized in water and chain extended with methyl methacrylate (MMA) as hydrophobic monomer, inspired by a polymerization-induced self-assembly (PISA) process. This yielded latex nanoparticles with a hydrophobic PMMA core stabilized by the hydrophilic XG chains at the corona. The molar mass of PMMA targeted was varied, resulting in a series of stable latex particles with hydrophobic PMMA content between 22 and 68 wt % of the total solids content (5-10%). The XG-PMMA nanoparticles were subsequently adsorbed to a neutral cellulose substrate (filter paper), and the modified surfaces were analyzed by FT-IR and SEM analyses. The adsorption of the latex particles was also investigated by quartz crystal microbalance with dissipation monitoring (QCM-D), where the nanoparticles were adsorbed to negatively charged model cellulose surfaces. The surfaces were analyzed by atomic force microscopy (AFM) and contact angle (CA) measurements. QCM-D experiments showed that more mass was adsorbed to the surfaces with increasing molar mass of the PMMA present. AFM of the surfaces after adsorption showed discrete particles, which were no longer present after annealing (160 °C, 1 h) and the roughness (Rq) of the surfaces had also decreased by at least half. Interestingly, after annealing, the surfaces did not all become more hydrophobic, as monitored by CA measurements, indicating that the surface roughness was an important factor to consider when evaluating the surface properties following particle adsorption. This novel class of latex nanoparticles provides an excellent platform for cellulose modification via physical adsorption. The utilization of XG as the anchoring molecule to cellulose provides a versatile methodology, as it does not rely on electrostatic interactions for the physical adsorption, enabling a wide range of cellulose substrates to be modified, including neutral sources such as cotton and bacterial nanocellulose, leading to new and advanced materials.

  • 80.
    Henriksson, Marielle
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Isaksson, Per
    Solid Mechanics Department, Mid Sweden University, Sundsvall.
    Lindström, Tom
    STFI-Packforsk AB.
    Nishino, Takashi
    Chemical Science and Engineering Department, Faculty of Engineering, Kobe University.
    Cellulose nanopaper structures of high toughness2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 6, p. 1579-1585Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils offer interesting potential as a native fibrous constituent of mechanical performance exceeding the plant fibers in current use for commercial products. In the present study, wood nanofibrils are used to prepare porous cellulose nanopaper of remarkably high toughness. Nanopapers of different porosities and from nanofibrils of different molar mass are prepared. Uniaxial tensile tests are performed and structure-property relationships are discussed. The high toughness of highly porous nanopaper is related to the nanofibrillar network structure and high mechanical nanofibril performance. Also, molar mass correlates with tensile strength. This indicates that nanofibril fracture controls ultimate strength. Furthermore, the large strain-to-failure means that mechanisms, such as interfibril slippage, also contributes to inelastic deformation in addition to deformation of the nanofibrils themselves.

  • 81.
    Holmgren, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Zhang, Liming
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effects of a Biologically Relevant Antioxidant on the Dehydrogenative Polymerization of Coniferyl Alcohol2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 12, p. 3378-3382Article in journal (Refereed)
    Abstract [en]

    Dehydrogenation polymers (DHPs or synthetic lignins) were synthesized from coniferyl alcohol by enzymatic oxidation in the presence of ascorbic acid to study the potential effects of an antioxidant upon their structure. Specific interunit substructures (beta-O-4', beta-beta', and beta-5') were quantified by C-13 NMR, which showed how ascorbic acid altered their amounts compared with control syntheses without this antioxidant, especially by increasing the amount of beta-O-4' substructures. The effect of ascorbic acid increased with its concentration. Surprisingly, no influence on the sizes of the synthetic lignins, as determined by size exclusion chromatography, was observed. The chemistry of this antioxidant effect during dehydrogenative polymerization and the potential biological significance (cell wall lignification) of these observations are discussed.

  • 82.
    Hua, Geng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Exploiting Ring-Opening Aminolysis–Condensation as a Polymerization Pathway to Structurally Diverse Biobased Polyamides2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    A pathway to biobased polyamides (PAs) via ring-opening aminolysis–condensation (ROAC) under benign conditions with diverse structure was designed. Ethylene brassylate (EB), a plant oil-derived cyclic dilactone, was used in combination with an array of diamines of diverse chemical structure, and ring-opening of the cyclic dilactone EB was revealed as a driving force for the reaction. The ROAC reactions were adjusted, and reaction conditions of 100 °C under atmospheric pressure using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst for 24 h were optimal. The structures of the polyamides were confirmed by mass spectroscopy, FTIR, and NMR, and the PAs had viscosity average molecular weights (Mη) of ∼5–8 kDa. Glassy or semicrystalline PAs with glass transition temperatures between 48 and 55 °C, melting temperatures of 120–200 °C for the semicrystalline PAs, and thermal stabilities above 400 °C were obtained and were comparable to the existing PAs with similar structures. As a proof-of-concept of their usage, one of the PAs was shown to form fibers by electrospinning and films by melt pressing. Compared to conventional methods for PA synthesis, the ROAC route portrayed a reaction temperature at least 60–80 °C lower, could be readily carried out without a low-pressure environment, and eliminated the use of solvents and toxic chemicals. Together with the plant oil-derived monomer (EB), the ROAC route provided a sustainable alternative to design biobased PAs.

  • 83.
    Hui, Sun
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Wirsen, Anders
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Electron beam-induced graft polymerization of acrylic acid and immobilization of arginine-glycine-aspartic acid-containing peptide onto nanopatterned polycaprolactone2004In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 5, no 6, p. 2275-2280Article in journal (Refereed)
    Abstract [en]

    Electron beam- (EB-) induced graft polymerization of acrylic acid and the subsequent immobilization of arginine-glycine-aspartic acid (RGD) peptide onto nanopatterned polycaprolactone with parallel grooves is reported. A high concentration of carboxylic groups was introduced onto the polymer substrate by EB-induced polymerization of acrylic acid. In the coupling of the RGD peptide to the carboxylated polymer surface a three-step peptide immobilization process was used. This process included the activation of surface carboxylic acid into an active ester intermediate by use of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), the introduction of disulfide groups by use of 2-(2-pyridinyldithio)ethanamine tie hydrochloride (PDEA), and final immobilization of the peptide via a thioldisulfide exchange reaction. The extent of coupling was measured by UV spectroscopy. A preliminary study of the in vitro behavior of keratinocytes (NCTC 2544) cultured on the acrylic acid-grafted and RGD peptide-coupled surface showed that most cells grown on the coupled samples had a spread-rounded appearance, while the majority of cells tended to be elongated along the grooves on uncoupled substrates.

  • 84.
    Höglund, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Migration and Hydrolysis of Hydrophobic Polylactide Plasticizer2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 1, p. 277-283Article in journal (Refereed)
    Abstract [en]

    Hydrophobic plasticizer protects polylactide (PLA) against hydrolytic degradation but still migrates to aging medium and there undergoes further hydrolysis contributing to the spectrum of degradation products. PLA plasticized with hydrophobic acetyl tributyl citrate (ATC) plasticizer showed a slower degradation rate compared with pure PLA because of the increased hydrophobicity of the material. The enhanced bulk hydrophobicity also overcame the degradation enhancing effect of hydrophilic surface grafting. In addition to plasticization with ATC, some of the samples were also surface grafted with acrylic acid. The materials were subjected to hydrolysis at 37 and 60 degrees C for up to 364 days to compare the effect of hydrophobic and hydrophilic bulk and surface modifications. Although considered insoluble in water, the plasticizer was detected in the water solutions immediately upon immersion of the materials, and the relative abundance of the ATC degradation products increased with hydrolysis time.

  • 85.
    Höglund, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Controllable Degradation Product Migration from Cross-Linked Biomedical Polyester-Ethers through Predetermined Alterations in Copolymer Composition2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 6, p. 2025-2032Article in journal (Refereed)
    Abstract [en]

    Uniformly degrading biomaterials with adjustable degradation product migration rates were customized by combining the advantages of cross-linked poly(epsilon-caprolactone) with the hydrophilic character of poly(1,5-dioxepan-2-one). Hydrolytic degradation of these random cross-linked networks using 2,2'-bis-(epsilon-caprolactone-4-yl) propane (BCP) as the cross-linking agent was studied for up to 546 days in phosphate buffer solution at pH 7.4 and 37 degrees C. The hydrophilicity of the materials was altered by varying the copolymer compositions. After different hydrolysis times the materials were characterized, and the degradation products were extracted from the buffer solution and analyzed. Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, scanning electron microscopy, and gas chromatography-mass spectrometry were used to observe the changes taking place during the hydrolysis. From the results it was concluded that degradation profiles and migration of degradation products are controllable by tailoring the hydrophilicity of cross-linked polyester-ether networks.

  • 86.
    Ibn Yaich, Anas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Wood Hydrolysate Barriers: Performance Controlled via Selective Recovery2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 2, p. 466-473Article in journal (Refereed)
    Abstract [en]

    Films and coatings were produced from a noncellulosic polysaccaride-rich wood hydrolysate (WH) and the resulting oxygen barrier performance was improved by a selective choice of upgrading conditions. The WH was obtained from process water in the hydrothermal treatment of hardwood and subjected to one of three alternative upgrading treatments, resulting in xylan-rich fractions with significant differences in structure, composition, and properties of the recovered WH fractions, which in turn had a major impact on their performance with respect to tensile and oxygen barrier properties. The WH in the least upgraded state, the crudest fraction, produced films with the best performance in terms of oxygen permeability and was superior to corresponding films based on highly purified hemicellulose.

  • 87. Inkinen, Saara
    et al.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sodergard, Anders
    From Lactic Acid to Poly(lactic acid) (PLA): Characterization and Analysis of PLA and Its Precursors2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 3, p. 523-532Article, review/survey (Refereed)
    Abstract [en]

    The quality of the monomers lactic acid and lactide as well as the chemical changes induced during polymerization and processing are crucial parameters for controlling the properties of the resulting poly(lactic acid) (PLA) products. This review presents the most important analysis and characterization methods for quality assessment of PLA and its precursors. The impurities typically present in lactic acid or lactide monomers and their possible origins and effects on resulting PLA products are discussed. The significance of the analyses for the different polymer production stages is considered, and special applications of the methods for studying features specific for PLA-based materials are highlighted.

  • 88. Jansson, Ronnie
    et al.
    Thatikonda, Naresh
    Lindberg, Diana
    Rising, Anna
    Johansson, Jan
    Nygren, Per-Åke
    KTH, School of Biotechnology (BIO), Protein Technology.
    Hedhammar, My
    Recombinant Spider Silk Genetically Functionalized with Affinity Domains2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 5, p. 1696-1706Article in journal (Refereed)
    Abstract [en]

    Functionalization of biocompatible materials for presentation of active protein domains is an area of growing interest. Herein, we describe a strategy for functionalization of recombinant spider silk via gene fusion to affinity domains of broad biotechnological use. Four affinity domains of different origin and structure; the IgG-binding domains Z and C2, the albumin-binding domain ABD, and the biotin-binding domain M4, were all successfully produced as soluble silk fusion proteins under nondenaturing purification conditions. Silk films and fibers produced from the fusion proteins were demonstrated to be chemically and thermally stable. Still, the bioactive domains are concluded to be folded and accessible, since their respective targets could be selectively captured from complex samples, including rabbit serum and human plasma. Interestingly, materials produced from mixtures of two different silk fusion proteins displayed combined binding properties, suggesting that tailor-made materials with desired stoichiometry and surface distributions of several binding domains can be produced. Further, use of the IgG binding ability as a general mean for presentation of desired biomolecules could be demonstrated for a human vascular endothelial growth factor (hVEGF) model system, via a first capture of anti-VEGF IgG to silk containing the Z-domain, followed by incubation with hVEGF. Taken together, this study demonstrates the potential of recombinant silk, genetically functionalized with affinity domains, for construction of biomaterials capable of presentation of almost any desired biomolecule.

  • 89.
    Joby Kochumalayil, Jose
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Bergenstråhle-Wohlert, Malin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Bioinspired and highly oriented clay nanocomposites with a xyloglucan biopolymer matrix: Extending the range of mechanical and barrier properties2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 1, p. 84-91Article in journal (Refereed)
    Abstract [en]

    The development of clay bionanocomposites requires processing routes with nanostructural control. Moreover, moisture durability is a concern with water-soluble biopolymers. Here, oriented bionanocomposite coatings with strong in-plane orientation of clay platelets are for the first time prepared by continuous water-based processing. Montmorillonite (MTM) and a "new" unmodified biological polymer (xyloglucan (XG)) are combined. The resulting nanocomposites are characterized by FE-SEM, TEM, and XRD. XG adsorption on MTM is measured by quartz crystal microbalance analysis. Mechanical and gas barrier properties are measured, also at high relative humidity. The reinforcement effects are modeled. XG dimensions in composites are estimated using atomistic simulations. The nanostructure shows highly oriented and intercalated clay platelets. The reinforcement efficiency and effects on barrier properties are remarkable and are likely to be due to highly oriented and well-dispersed MTM and strong XG-MTM interactions. Properties are well preserved in humid conditions and the reasons for this are discussed.

  • 90.
    Johansson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lundström, Lisa
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Norgren, Magnus
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Adsorption Behavior and Adhesive Properties of Biopolyelectrolyte Multilayers formed from Cationic and Anionic Starch2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 7, p. 1768-1776Article in journal (Refereed)
    Abstract [en]

    Cationic starch (D.S. 0.065) and anionic starch (D.S. 0.037) were used to form biopolyelectrolyte multilayers. The influence of the solution concentration of NaCl on the adsorption of starch onto silicon oxide substrates and on the formation of multilayers was investigated using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). The wet adhesive properties of the starch multilayers were examined by measuring pull-off forces with the AFM colloidal probe technique. It was shown that polyelectrolyte multilayers (PEM) can be successfully constructed from cationic starch and anionic starch at electrolyte concentrations of 1 mM NaCl and 10 mM NaCl. The water content of the PEMs was approximately 80% at both electrolyte concentrations. However, the thickness of the PEMs formed at 10 mM NaCl was approximately twice the thickness formed at I mM NaCl. The viscoelastic properties of the starch PEMs, modeled as Voigt elements, were dependent on the polyelectrolyte that was adsorbed in the outermost layer. The PEMs appeared to be more rigid when capped by anionic starch than when capped by cationic starch. The wet adhesive pull-off forces increased with layer number and were also dependent oil the polyelectrolyte adsorbed in the outermost layer. Thus, starch PEM treatment has a large potential for increasing the adhesive interaction between solid substrates to levels higher than can be reached by a single layer of cationic starch.

  • 91.
    Johansson, Jan-Å
    et al.
    Ångström Laboratory, Department of Materials Chemistry, Uppsala University.
    Halthur, Tobias
    YKI, Institute for Surface Chemistry.
    Herranen, Merja
    Ångström Laboratory, Department of Materials Chemistry, Uppsala University.
    Söderberg, Lennart
    Center for Surface Biotechnology, Uppsala University.
    Elofsson, Ulla
    YKI, Institute for Surface Chemistry.
    Hilborn, Jöns
    Ångström Laboratory, Department of Materials Chemistry, Uppsala University.
    Build-up of Collagen and Hyaluronic Acid Polyelectrolyte2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 3, p. 1353-1359Article in journal (Refereed)
    Abstract [en]

    We have used a novel polyelectrolyte multilayer (PEM) coating consisting of the polyelectrolytes collagen and hyaluronic acid. The build-up by the layer-by-layer deposition technique is outlined by ex situ and in situ ellipsometric measurements. When collagen was added, the thickness of the PEM was increased, and the refractive index was decreased. Corresponding but opposite effects were noted when hyaluronic acid was added. These changes are considered to be explained by a diffusion mechanism. It was also found that the PEM layers were unstable at physiological pH. However, by cross-linking using N-(3-di-methylaminopropyl)-N-ethylcarbodiimide together with N-hydroxysuccinimide, a stable PEM layer resulted. These tissue friendly PEM layers are expected to have a great impact in the design of artificial extracellular matrixes. Also, the insertion of fluorescence labels demonstrates the potential for incorporation of other functionalities.

  • 92. Josefsson, Peter
    et al.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    The physical action of cellulases revealed by a quartz crystal microbalance study using ultrathin cellulose films and pure2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 1, p. 249-254Article in journal (Refereed)
    Abstract [en]

    The effects of fungal cellulases on model cellulose films were studied using a high-resolution quartz crystal microbalance (QCM) sensitive to minute changes of the nanometer thick model cellulose films. It was found that endoglucanases not only produce new end groups but also cause a swelling of the cellulose film. The cellobiohydrolases degraded the films quickly, which was detected as a rapid decrease in the remaining amount of cellulose on the QCM crystal. However, changing viscoelastic properties of the films also indicated a softening of the film during the degradation. A defined mixture of selected cellulases caused a significantly higher rate of degradation than only cellobiohydrolases. Cellulase synergism is discussed with the endoglucanase swelling effects and film softening added.

  • 93. Kaesdorf, Benjamin T.
    et al.
    Weber, Florian
    Petrou, Georgia
    KTH, School of Biotechnology (BIO), Glycoscience.
    Srivastava, Vaibhav
    KTH, School of Biotechnology (BIO), Glycoscience.
    Crouzier, Thomas
    KTH, School of Biotechnology (BIO), Glycoscience.
    Lieleg, Oliver
    Mucin-Inspired Lubrication on Hydrophobic Surfaces2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 8, p. 2454-2462Article in journal (Refereed)
    Abstract [en]

    In the human body, high-molecular-weight glycoproteins called mucins play a key role in protecting epithelial surfaces against pathogenic attack, controlling the passage of molecules toward the tissue and enabling boundary lubrication with very low friction coefficients. However, neither the molecular mechanisms nor the chemical motifs of those biomacromolecules involved in these fundamental processes are fully understood. Thus, identifying the key features that render biomacromolecules such as mucins outstanding boundary lubricants could set the stage for creating versatile artificial superlubricants. We here demonstrate the importance of the hydrophobic terminal peptide domains of porcine gastric mucin (MUCSAC) and human salivary mucin (MUCSB) in the processes of adsorbing to and lubricating a hydrophobic PDMS surface. Tryptic digestion of those mucins results in removal of those terminal domains, which is accompanied by a loss of lubricity as well as surface adsorption. We show that this loss can in part be compensated by attaching hydrophobic phenyl groups to the glycosylated central part of the mucin macromolecule. Furthermore, we demonstrate that the simple biopolysaccharide dextran can be functionalized with hydrophobic groups which confers efficient surface adsorption and good lubricity on PDMS to the polysaccharide.

  • 94.
    Kaldéus, Tahani
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Leggieri, Maria Rosella Telaretti
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sanchez, Carmen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    All-Aqueous SI-ARGET ATRP from Cellulose Nanofibrils Using Hydrophilic and Hydrophobic Monomers2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 5, p. 1937-1943Article in journal (Refereed)
    Abstract [en]

    An all-water-based procedure for "controlled" polymer grafting from cellulose nanofibrils is reported. Polymers and copolymers of poly(ethylene glycol) methyl ether methacrylate (POEGMA) and poly(methyl methacrylate) (PMMA) were synthesized by surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET ATRP) from the cellulose nanofibril (CNF) surface in water. A macroinitiator was electrostatically immobilized to the CNF surface, and its amphiphilic nature enabled polymerizations of both hydrophobic and hydrophilic monomers in water. The electrostatic interactions between the macroinitiator and the CNF surface were studied by quartz crystal microbalance with dissipation energy (QCM-D) and showed the formation of a rigid adsorbed layer, which did not desorb upon washing, corroborating the anticipated electrostatic interactions. Polymerizations were conducted from dispersed modified CNFs as well as from preformed modified CNF aerogels soaked in water. The polymerizations yielded matrix-free composite materials with a CNF content of approximately 1-2 and 3-6 wt % for dispersion-initiated and aerogel-initiated CNFs, respectively.

  • 95. Karlsson, A.
    et al.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    New selective method for quantification of organosilanol groups in silicone pre-elastomers2002In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 4, p. 850-856Article in journal (Refereed)
    Abstract [en]

    The silicone elastomers used for drug delivery are normally reinforced by fumed silica, which contains a high density of silanol groups. These inorganic silanol groups have to be deactivated in order to avoid stiffening the uncured pre-elastomer. also called creep hardening. One commonly used way of achieving this deactivation is to mix the material with low molecular mass organosilanols at an elevated temperature, It is important to be able to quantify the nonbonded organosilanols remaining in the material after manufacture. Traditional testing does not distinguish between inorganic silanols and organosilanols, A new selective method for the quantification of organosilanol groups in silicone pre-elastomers has therefore been developed, This method is based on derivatization of the silanol groups with a Mixture of dimethylphenylchlorosilane and tetramethyldiphenylsilazane, so that the silanol group, are replaced with a dimethylphenyl group. The derivatized organosilanols are then determined by liquid chromatography using a size exclusion column and a UV detector. No interference was found from other groups normally present in medical grade pre-elastomers, such as vinyls, hydrides, and inorganic bonded silanol on silica or water. The results agreed well with the nonselective Karl Fischer titration for some short chain silanols.

  • 96.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. RISE Bioeconomy.
    Hansson, Per
    Uppsala University, Dep. of Pharmacy, Uppsala Biomedical Center.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Thermodynamics of the Water-Retaining Properties of Cellulose-Based Networks2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 4, p. 1603-1612Article in journal (Refereed)
    Abstract [en]

    Noncrystalline cellulose-based gel beads were used as a model material to investigate the effect of osmotic stress on a cellulosic network. The gel beads were exposed to osmotic stress by immersion in solutions with different concentrations of high molecular mass dextran and the equilibrium dimensional change of the gel beads was studied using optical microscopy. The volume fraction of cellulose was calculated from the volume of the gel beads in dextran solutions and their dry content and the relation between the cellulose volume fraction and the total osmotic pressure was thus obtained. The results show that the contribution to the osmotic pressure from counterions increases the water-retaining capacity of the beads at high osmotic pressures but also that the main factor controlling the gel bead collapse at high osmotic strains is the resistance to the deformation of the polymer chain network within the beads. Furthermore, the osmotic pressure associated with the deformation of the polymer network, which counteracts the deswelling of the beads, could be fitted to the Wall model indicating that the response of the cellulose polymer networks was independent of the charge of the cellulose. The best fit to the Wall model was obtained when the Flory-Huggins interaction parameter () of the cellulose-water system was set to 0.55-0.60, in agreement with the well-established insolubility of high molecular mass β-(1,4)-d-glucan polymers in water.

  • 97. Khabbaz, F.
    et al.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Great advantages in using a natural rubber instead of a synthetic SBR in a pro-oxidant system for degradable LDPE2000In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 1, no 4, p. 665-673Article in journal (Refereed)
    Abstract [en]

    Different pro-oxidant systems are used in degradable low-density polyethylene (LDPE). The main question is the degradation products and not the degradation time from the used materials. The pro-oxidant formulation used consisted of manganese stearate and natural rubber (NR) or manganese stearate and a synthetic, styrene-butadiene copolymer rubber (SBR). The samples were heated in air at 100 degreesC in sealed glass vials. The molecular weight changes were measured by size exclusion chromatography (SEC). The volatile and nonvolatile degradation products have been identified by gas chromatography-mass spectrometry (GC/MS). A wide variety of degradation products were identified, including ketones, carboxylic acids, keto acids, dicarboxylic acids, and furanones as a homologous series. Benzaldehyde, acetophenone, benzoic acid, benzyl benzoate, and two benzene derivative compounds were identified only in the LDPE-SBR system. These aromatic compounds originate from the styrene parr of SBR. The advantages using pro-oxidant containing NR are more effective degradation of LDPE without any aromatic degradation products.

  • 98. Kiemle, Sarah N.
    et al.
    Zhang, Xiao
    Esker, Alan R.
    Toriz, Guillermo
    Gatenholm, Paul
    Wallenberg Wood Sci Ctr, Gothenburg, Sweden.
    Cosgrove, Daniel J.
    Role of (1,3)(1,4)-beta-Glucan in Cell Walls: Interaction with Cellulose2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 5, p. 1727-1736Article in journal (Refereed)
    Abstract [en]

    (1,3)(1,4)-beta-D-Glucan (mixed-linkage glucan or MLG), a characteristic hemicellulose in primary cell walls of grasses, was investigated to determine both its role in cell walls and its interaction with cellulose and other cell wall polysaccharides in vitro. Binding isotherms showed that MLG adsorption onto microcrystalline cellulose is slow, irreversible, and temperature-dependent. Measurements using quartz crystal microbalance with dissipation monitoring showed that MLG adsorbed irreversibly onto amorphous regenerated cellulose, forming a thick hydrogel. Oligosaccharide profiling using endo-(1,3)(1,4)-beta-glucanase indicated that there was no difference in the frequency and distribution of (1,3) and (1,4) links in bound and unbound MLG. The binding of MLG to cellulose was reduced if the cellulose samples were first treated with certain cell wall polysaccharides, such as xyloglucan and glucuronoarabinoxylan. The tethering function of MLG in cell walls was tested by applying endo-(1,3)(1,4)-beta-glucanase to wall samples in a constant force extensometer. Cell wall extension was not induced, which indicates that enzyme-accessible MLG does not tether cellulose fibrils into a load-bearing network.

  • 99.
    Kishani, Saina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Xu, Wenyang
    Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
    Xu, Chunlin
    Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Solubility of Softwood Hemicelluloses2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 4, p. 1245-1255Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that the molecular solubility of softwood hemicelluloses is significantly influenced by pretreatment of the fibers, extraction, and downstream processing. To quantify these effects, four hemicellulose samples were extracted from different thermomechanical pulps of Norway spruce. The molecular solubility of the samples was characterized by size and molar mass distributions, and the morphology of the molecules was studied using high resolution microscopy techniques. All extracted samples were well dispersed in aqueous media creating transparent dispersions, but dynamic light scattering measurements showed that molecular solubility can only be achieved using specific pretreatments and extractions. The procedure yields acetylated galactoglucomannan (AcGGM)-rich hemicelluloses with an average molar mass of 21-35 kDa and a diameter up to 10 nm but also shows that water is a poor solvent for this sample since an association is detected as soon as the concentration is about 20 g/L. These associated hemicellulose dispersions are still absolutely dear on visual inspection, underlining the need for careful measurement when assessing the solubility of wood hemicelluloses.

  • 100.
    Kochumalayil, Joby Kochumalayil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Morimune, Seira
    Nishino, Takashi
    Ikkala, Olli
    Walther, Andreas
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nacre-Mimetic Clay/Xyloglucan Bionanocomposites: A Chemical Modification Route for Hygromechanical Performance at High Humidity2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 11, p. 3842-3849Article in journal (Refereed)
    Abstract [en]

    Nacre-mimetic bionanocomposites of high montmorillonite (MTM) clay content, prepared from hydra. colloidal suspensions, suffer from reduced strength and stiffness at high relative humidity. We address this problem by chemical modification of xyloglucan in (XG)/MTM nacremimetic nanocomposites, by subjecting the XG to regioselective periodate oxidation of side chains to enable it to form covalent cross-links to hydroxyl groups in neighboring XG chains or to the MTM surface. The resulting materials are analyzed by FTIR spectroscopy, thermogravimetric analysis, carbohydrate analysis, calorimetry, X-ray diffraction, scanning electron microscopy, tensile tests, and oxygen barrier properties. We compare the resulting mechanical properties at low and high relative humidity. The periodate oxidation leads to a strong increase in modulus and strength of the materials. A modulus of 30 GPa for cross-linked composite at 50% relative humidity compared with 13.7 GPa for neat XG/MTM demonstrates that periodate oxidation of the XG side chains leads to crucially improved stress transfer at the XG/MTM interface, possibly through covalent bond formation. This enhanced interfacial adhesion and internal cross-linking of the matrix moreover preserves the mechanical properties at high humidity condition and leads to a Young's modulus of 21 GPa at 90%RH.

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