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  • 201.
    Xu, Yunsheng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hua, Geng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Isosorbide as Core Component for Tailoring Biobased Unsaturated Polyester Thermosets for a Wide Structure- Property Window2018Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 7, s. 3077-3085Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biobased unsaturated polyester thermosets as potential replacements for petroleum-based thermosets were designed. The target of incorporating rigid units, to yield thermosets with high thermal and mechanical performance, both in the biobased unsaturated polyester (UP) and reactive diluent (RD) while retaining miscibility was successfully achieved. The biobased unsaturated polyester thermosets were prepared by varying the content of isosorbide, 1,4-butanediol, maleic anhydride, and succinic anhydride in combination with the reactive diluent isosorbide-methacrylate (IM). Isosorbide was chosen as the main component in both the UP and the RD to enhance the rigidity of the formed thermosets, to overcome solubility issues commonly associated with biobased UPs and RDs and volatility and toxicity associated with styrene as RD. All UPs had good solubility in the RD and the viscosity of the mixtures was primarily tuned by the feed ratio of isosorbide but also by the amount of maleic anhydride. The flexural modulus and storage modulus were tailorable by altering the monomer composition The fabricated thermosets had superior thermal and mechanical properties compared to most biobased UP thermosets with thermal stability up to about 250 degrees C and a storage modulus at 25 degrees C varying between 0.5 and 3.0 GPa. These values are close to commercial petroleum-based UP thermosets. The designed tailorable biobased thermosets are, thus, promising candidates to replace their petroleum analogs.

  • 202.
    Yang, Xuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berthold, Fredrik
    RISE Res Inst Sweden, Master Samuelsgatan 60, SE-11121 Stockholm, Sweden..
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Preserving Cellulose Structure: Delignified Wood Fibers for Paper Structures of High Strength and Transparency2018Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 7, s. 3020-3029Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt %) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10 degrees). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young's modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as "glue" in the interfiber region, improving both mechanical and optical properties of papers. Holocellulose fibers may be affordable and applicable candidates for making special paper/composites where high mechanical performance and/or optical transmittance are of interest.

  • 203.
    Yin, Yafang
    et al.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Salmen, Lennart
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Effect of Steam Treatment on the Properties of Wood Cell Walls2011Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, nr 1, s. 194-202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Steam treatment is a hygrothermal method of potential industrial significance for improving the dimensional stability and durability of wood materials. The steaming results in different chemical and micromechanical changes in the nanostructured biocomposite that comprise a wood cell wall. In this study, spruce wood (Picea abies Karst.) that had been subjected to high-temperature steaming up to 180 degrees C was examined, using imaging Fourier Transform Infrared (FT-IR) microscopy and nanoindentation to track changes in the chemical structure and the micromechanical properties of the secondary cell wall. Similar changes in the chemical components, due to the steam treatment, were found in earlywood and latewood. A progressive degradation of the carbonyl groups in the glucuronic acid unit of xylan and a loss of mannose units in the glucomannan backbone, that is, a degradation of glucomannan, together with a loss of the C=O group linked to the aromatic skeleton in lignin, was found. The development of the hygroscopic and micromechanical properties that occurred with an elevation in the steam temperature correlated well with this pattern of degradation in the constituents in the biocomposite matrix in the cell wall (hemicellulose and lignin).

  • 204.
    Zhao, Weifeng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Sichuan University, China.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Zhao, Changsheng
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    In Situ Synthesis of Magnetic Field-Responsive Hemicellulose Hydrogels for Drug Delivery2015Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 8, s. 2522-2528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A one-pot synthetic methodology for fabricating stimuli-responsive hemicellulose-based hydrogels was developed that consists of the in situ formation of magnetic iron oxide (Fe3O4) nanoparticles during the covalent cross-linking of O-acetyl-galactoglucomannan (AcGGM). The Fe3O4 nanoparticle content controlled the thermal stability, macrostructure, swelling behavior, and magnetization of the hybrid hydrogels. In addition, the magnetic field-responsive hemicellulose hydrogels (MERHHs) exhibited excellent adsorption and controlled release profiles with bovine serum albumin (BSA) as the model drug. Therefore, the MFRHHs have great potential to be utilized in the biomedical field for tissue engineering applications, controlled drug delivery, and magnetically assisted bioseparation. Magnetic field-responsive hemicellulose hydrogels, prepared using a straightforward one-step process, expand the applications of biomass-derived polysaccharides by combining the renewability of hemicellulose and the magnetism of Fe3O4 nanoparticles.

  • 205.
    Zheng, Jukuan
    et al.
    University of Akron, United States .
    Kontoveros, Dimitria
    University of Akron, United States .
    Lin, Fei
    University of Akron, United States .
    Hua, Geng
    University of Akron, United States .
    Reneker, Darrell H.
    University of Akron, United States .
    Becker, Matthew L.
    University of Akron, United States .
    Willits, Rebecca K.
    University of Akron, United States .
    Enhanced Schwann Cell Attachment and Alignment Using One-Pot “Dual Click” GRGDS and YIGSR Derivatized Nanofibers2015Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 1, s. 357-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using metal-free click chemistry and oxime condensation methodologies, GRGDS and YIGSR peptides were coupled to random and aligned degradable nanofiber networks postelectrospinning in a one-pot reaction. The bound peptides are bioactive, as demonstrated by Schwann cell attachment and proliferation, and the inclusion of YIGSR with GRGDS alters the expression of the receptor for YIGSR. Additionally, aligned nanofibers act as a potential guidance cue by increasing the aspect ratio and aligning the actin filaments, which suggest that peptide-functionalized scaffolds would be useful to direct SCs for peripheral nerve regeneration.

  • 206.
    Zhou, Juan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Butchosa, Núria
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Jayawardena, H. Surangi N.
    University of Massachusetts, United States .
    Park, JaeHyeung
    University of Massachusetts, United States .
    Zhou, Qi
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi. University of Massachusetts, United States .
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Synthesis of Multifunctional Cellulose Nanocrystals for Lectin Recognition and Bacterial Imaging2015Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 4, s. 1426-1432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multifunctional cellulose nanocrystals have been synthesized and applied as a new type of glyconanomaterial in lectin binding and bacterial imaging. The cellulose nanocrystals were prepared by TEMPO-mediated oxidation and acidic hydrolysis, followed by functionalization with a quinolone fluorophore and carbohydrate ligands. The cellulose nanocrystals were subsequently applied in interaction studies with carbohydrate-binding proteins and in bacterial imaging. The results show that the functional cellulose nanocrystals could selectively recognize the corresponding cognate lectins. In addition, mannosylated nanocrystals were shown to selectively interact with FimH-presenting E. coli, as detected by TEM and confocal fluorescence microscopy. These glyconanomaterials provide a new application of cellulose nanocrystals in biorecognition and imaging.

  • 207.
    Zhu Ryberg, Yingzhi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Conceptual approach to renewable barrier film design based on wood hydrolysate2011Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, nr 4, s. 1355-1362Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass is converted to oxygen barriers through a conceptually unconventional approach involving the preservation of the biomass native interactions and macromolecular components and enhancing the effect by created interactions With a co-component. A combined calculation/assessment model is elaborated to understand, quantify, and predict which compositions that provide an intermolecular affinity high enough to mediate the molecular packing needed to create a functioning barrier. The biomass used is a wood hydrolysate, a polysaccharide-rich but not highly refined mixture where a fair amount of the native intermolecular and intramolecular hernicelluloses-lignin interactions are purposely preserved, resulting in barriers with very low oxygen permeabilities (OP) both at 50 and 80% relative humidity and, considerably lower OPs than coatings based on the corresponding highly purified spruce hemicellulose, O-acetyl galactoglucomannan (AcGGM). The component interactions and, mutual affinities effectively mediate an immobilization of the chain segments in a dense disordered structure, modeled through the Hansen's solubility parameter concept and quantified on the nanolength scale by positron annihilation lifetime spectrum (PALS).

  • 208.
    Zhu Ryberg, Yingzhi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Retrostructural model to predict biomass formulations for barrier performance2012Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, nr 8, s. 2570-2577Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Barrier performance and retrostructural modeling of the macromolecular components demonstrate new design principles for film formulations based on renewable wood hydrolysates. Hardwood hydrolysates, which contain a fair share of lignin coexisting with poly- and oligosaccharides, offer excellent oxygen-barrier performance. A Hansen solubility parameter (HSP) model has been developed to convert the complex hydrolysate structural compositions into relevant matrix oxygen-permeability data allowing a systematic prediction of how the biomass should be formulated to generate an efficient barrier. HSP modeling suggests that the molecular packing ability plays a key role in the barrier performance. The actual size and distribution of free volume holes in the matrices were quantified in the subnanometer scale with Positron annihilation lifetime spectroscopy (PALS) verifying the affinity-driven assembly of macromolecular segments in a densely packed morphology and regulating the diffusion of small permeants through the matrix. The model is general and can be adapted to determine the macromolecular affinities of any hydrolysate biomass based on chemical composition.

  • 209.
    Östmark, Emma
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Harrisson, Simon
    Center for Materials Innovation, Department of Chemistry, Washington University in Saint Louis.
    Wooley, Karen L.
    Center for Materials Innovation, Department of Chemistry, Washington University in Saint Louis.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Comb Polymers Prepared by ATRP from Hydroxypropyl Cellulose2007Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, nr 4, s. 1138-1148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydroxypropyl cellulose (HPC) was used as a core molecule for controlled grafting of monomers by ATRP, the aim being to produce densely grafted comb polymers. HPC was either allowed to react with an ATRP initiator or the first generation initiator-functionalized 2,2-bis(methylol)propionic acid dendron to create macroinitiators having high degrees of functionality. The macroinitiators were then "grafted from" using ATRP of methyl methacrylate (MMA) or hexadecyl methacrylate. Block copolymers were obtained by chain extending PMMA-grafted HPCs via the ATRP of tert-butyl acrylate. Subsequent selective acidolysis of the tert-butyl ester moieties was performed to form a block of poly(acrylic acid) resulting in amphiphilic block copolymer grafts. The graft copolymers were characterized by H-1 NMR and FT-IR spectroscopies, DSC, TGA, rheological measurements, DLS, and tapping mode AFM on samples spin coated upon mica. It was found that the comb (co)polymers were in the nanometer size range and that the dendronization had an interesting effect on the rheological properties.

  • 210.
    Östmark, Emma
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Lindqvist, Josefina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Nyström, Daniel
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Dendronized Hydroxypropyl Cellulose: Synthesis and Characterization of Biobased Nanoobjects2007Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, nr 12, s. 3815-3822Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dendronized polymers containing a cellulose backbone have been synthesized with the aim of producing complex molecules with versatile functionalization possibilites and high molecular weight from biobased starting materials. The dendronized polymers were built by attaching premade acetonide-protected 2,2-bis(methylol)propionic acid functional dendrons of generation one to three to a hydroxypropyl cellulose backbone. Deprotection or functionalization of the end groups of the first generation dendronized polymer to hydroxyl groups and long alkyl chains was performed, respectively. The chemical structures of the dendronized polymers were confirmed through analysis using H-1 NMR and FT-IR spectroscopies. From SEC analysis, the dendronized polymers were found to have an increasing polystyrene-equivalent molecular weight up to the second generation (M-n = 50 kg mol(-1)), whereas the polystyrene-equivalent molecular weight for the third generation was lower than for the second, although the same grafting density was obtained from H-1 NMR spectroscopy for the second and third generations. Tapping-mode atomic force microscopy was used to characterize the properties of the dendronized polymers in the dry state, exploring both the effect of the polar substrate mica and the less polar substrate highly oriented pyrolytic graphite (HOPG). It was found that the molecules were in the size range of tens of nanometers and that they were apt to undertake a more elongated conformation on the HOPG surfaces when long alkyl chains were attached as the dendron end-groups.

2345 201 - 210 of 210
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