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  • 151.
    Carrick, Christopher
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre 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.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Immunoselective cellulose nanospheres: a versatile platform for nanotheranostics2014In: ACS Macro Letters, E-ISSN 2161-1653, Vol. 3, no 11, p. 1117-1120Article in journal (Refereed)
    Abstract [en]

    This paper describes a novel route for the preparation and functionalization of perfectly spherical cellulose nanospheres (CNSs), ranging from 100 to 400 nrn with a typical diameter of 160-170 nrn,for use in theranostics. The method of preparation enables both surface and interior bulk functionalization, and this presumably also makes the CNSs suitable for use in end-use applications other than theranostics. Surface functionalization was here demonstrated by antibody conjugation with an antibody specific toward the epidermal growth factor receptor (EGFR) protein, i.e., facilitating interaction with cancer cells having the EGFR. Besides showing specificity, the CNS-antibody conjugates showed a very low nonspecific binding. The CNSs could easily be bulk functionalized by embedding gold nanoparticles in the cellulose sphere matrix during CNS preparation to provide imaging contrast for diagnostic purposes.

  • 152.
    Cederholm, Linnea
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Transformation of lignin into biobased thermoset2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Combined microwave assisted extraction/degradation of technical lignin in green solvents was successfully employed to generate polyphenolic oligomers with lower Mw than the starting material. For Lignoboost, the highest liquid yield (65 %) was obtained in 20 min at 160 °C using ethanol as solvent. This is an increase in ethanol soluble yield with 38 % compared to solvent extraction. The highest yield for Lignosulfonate was obtained with methanol as solvent, at 160 °C for 20 min. Obtained liquid fractions were analysed by SEC, FT-IR, DSC, TGA, 31P-NMR and 2D-HSQC NMR in order to explain the mechanism of the increased yield, and to study the structural changes after microwave extraction/degradation. 2D-NMR indicates cleavage of β-O-4 inter-unit linkages, but also that some modification around the bond could take place. Lignin based thermosets were synthesised employing the polyesterification between lignin, citric acid and poly(ethylene glycol) (PEG). It was concluded that introduction of PEG into the system was crucial for a homogenous thermoset synthesis with a high gel content. From TGA analysis it could be concluded that the thermoset based on original Lignoboost had a lower thermal stability than the counterparts prepared from lower molecular weight fractions. This implies that the esterification reaction between original Lignoboost and the other co-monomers is obstruct by sterically hindrance, which means that pre-conditioning is positive for the final material properties.

  • 153. Champ, Simon
    et al.
    Koch, Oliver
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Feuerhake, Robert
    Haehnle, Hans-Joachim
    Biocidal coatings2006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Biocidal multilayered system, characterized in that it comprises at least the following layers: - an anionic or cationic carrier, preferably cellulose as anionic carrier, - on this carrier alternating polymeric cationic and anionic layers starting with a layer having a charge opposite to that of the carrier, - wherein at least one layer is hydrophobically modified.

  • 154.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, M.
    Olsson, Rickard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    A novel chitosan/wheat gluten biofoam fabricated by spontaneous mixing and vacuum-drying2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 114, p. 94191-94200Article in journal (Refereed)
    Abstract [en]

    A new type of chitosan and wheat gluten biofoam is presented. The pore structure achieved relied solely on the specific mixing and phase distribution when a film was cast from an aqueous mixture of chitosan/wheat gluten solution, in the absence of any chemical blowing agent, porogen or expanding gas. The foam was obtained when the liquid phase was removed by vacuum drying, without the need for the traditional freeze-drying that is frequently used for pore formation. Soft foam samples could be prepared with stiffnesses from 0.3 to 1.2 MPa and a high rebound resilience (64 and 94% at compressive strains of 80 and 20%, respectively). The foams were relatively ductile and did not require any plasticiser to allow for in-plane deformation (20% compression) and smaller bending. Only open pores with sizes of the order of 70-80 μm were observed by microscopy. The density of all the foams was ∼50 kg m-3, due to the high porosity (96% air). The foams showed a rapid and large uptake of both non-polar (limonene) and polar (water) liquids. When immersed in these liquids for 1 second, the maximum uptake recorded was 40 times the initial mass of the foam for limonene and 8 times for water.

  • 155.
    Chen, Guo-Qiang
    et al.
    Tsinghua Univ, CSSB, Sch Life Sci, Beijing 100084, Peoples R China..
    Albertsson, Ann-Christine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Polyhydroxyalkanoates and Other Biopolymers2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 9, p. 3211-3212Article in journal (Other academic)
  • 156.
    Chen, Pan
    et al.
    Rhein Westfal TH Aachen, AICES Grad Sch, D-52062 Aachen, Germany..
    Ogawa, Yu
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Tokyo, Grad Sch Agr & Life Sci, Dept Biomat Sci, Bunkyo Ku, Tokyo 1138657, Japan..
    Nishiyama, Yoshiharu
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Grenoble Alpes, CERMAV, F-38000 Grenoble, France..
    Bergenstråhle Wohlert, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mazeau, Karim
    CERMAV, CNRS, F-38000 Grenoble, France.;Univ Grenoble Alpes, CERMAV, F-38000 Grenoble, France..
    Energetically favored alternative hydrogen bond of cellulose II and cellulose IIII2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 157.
    Cho, Sung-Woo
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Aging and heat-sealing properties of films based on wheat gluten2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Recently the research interest of the possibility of using wheat gluten (WG) as packaging material has greatly increased due to its combination of high gas barrier, attractive mechanical, film-forming and renewable properties. The source is also readily available and inexpensive on a worldwide basis. The glycerol-plasticized WG films cast from pH 4 and pH 11 solutions were investigated in order to understand the mechanisms behind the undesired aging. The film prepared from the pH 11 solution was mechanically more stable upon aging than the pH 4 film, which was initially very ductile but turning brittle with time. It was revealed that the protein structure of the pH 4 film was initially less polymerized/aggregated and the polymerization increased during storage but it did not reach the degree of aggregation of the pH 11 film, whereas deamidation was occurred and increased in the pH 11 film. During aging, the pH 4 film lost more mass than the pH 11 film mainly due to migration of glycerol but also due to some loss of volatile mass and the greater plasticizer loss of pH 4 film was presumably due to its initial lower degree of protein aggregation /polymerization. The glycerol migration of cast films exposed to a porous paper was further investigated with respect to pH of cast solution, glycerol content and film thickness since it was the main reason for deterioration of the properties. The opacity was also characterized. The glycerol migration was quantified using GC method in order to determine only glycerol content, but not other volatile substances. Glycerol content did not significantly change the opacity and pH 4 films showed good contact clarity because of less Maillard reaction. Glycerol was extensively migrating to the paper support and the migration seemed to be diffusion controlled. The heat sealability of WG films was investigated, using an impulse-hear sealer. It was observed that the WG films were readily sealable keeping up their integrity. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed.

  • 158.
    Cho, Sung-Woo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gällstedt, Mikael
    STFI-Packforsk AB .
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Comparison of properties of wheat gluten films prepared at pH 4 and pH 11; effects of glycerol content and film thicknessManuscript (Other academic)
  • 159.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Naderi, A.
    Iruthayaraj, J.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Vareikis, A.
    Makuska, R.
    Interfacial properties of bottle-brush polyelectrolytes2007In: PROCEEDINGS OF BALTIC POLYMER SYMPOSIUM 2007 / [ed] Makuska, R., Vilnius: VILNIUS UNIV. , 2007, p. 77-81Conference paper (Refereed)
    Abstract [en]

    This article is focused on interfacial properties of bottle brush polyelectrolytes, where side-chains are attached along a polymer backbone. This class of polymer has been much less studied than block copolymers, which is particularly true for bottle brush polyelectrolytes with a high graft density. We have explored how the graft density and charge density of such polymers affect surface properties, as well as some bulk properties. The adsorption of this class of polymer onto negatively charged silica and mica surfaces has been determined. On mica adsorption is driven by electrostatic forces whereas on silica both electrostatic forces and interactions between silica and ethylene oxide chains drive the adsorption. On silica the adsorbed amount is very sensitive to solution ionic strength and pH. We also report on surface interactions and frictional forces obtained between surfaces coated with bottle brush polyelectrolytes.

  • 160.
    Claudino, Mauro
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Thiol−ene Coupling of Renewable Monomers: at the forefront of bio-based polymeric materials2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Plant derived oils bear intrinsic double-bond functionality that can be utilized directly for the thiol–ene reaction. Although terminal unsaturations are far more reactive than internal ones, studies on the reversible addition of thiyl radicals to 1,2-disubstituted alkenes show that this is an important reaction. To investigate the thiol–ene coupling reaction involving these enes, stoichiometric mixtures of a trifunctional propionate thiol with monounsaturated fatty acid methyl esters (methyl oleate or methyl elaidate) supplemented with 2.0 wt.% Irgacure 184 were subjected to 365-nm UV-irradiation and the chemical changes monitored. Continuous (RT– FTIR) and discontinuous (NMR and FT–Raman) techniques were used to follow the progress of the reaction and reveal details of the products formed. Experimental results supported by numerical kinetic simulations of the system confirm the reaction mechanism showing a very fast cis/trans-isomerization of the alkene monomers (<1.0 min) when compared to the total disappearance of double-bonds, indicating that the rate-limiting step controlling the overall reaction is the hydrogen transfer from the thiol involved in the formation of final product. The loss of total unsaturations equals thiol consumption throughout the entire reaction; although product formation is strongly favoured directly from the trans-ene. This indicates that initial cis/trans-isomer structures affect the kinetics. High thiol–ene conversions could be easily obtained at reasonable rates without major influence of side-reactions demonstrating the suitability of this reaction for network forming purposes from 1,2-disubstituted alkenes. To further illustrate the validity of this concept in the formation of cross-linked thiol–ene films a series of globalide/caprolactone based copolyesters differing in degree of unsaturations along the backbone were photopolymerized in the melt with the same trithiol giving amorphous elastomeric materials with different thermal and viscoelastic properties. High thiol–ene conversions (>80%) were easily attained for all cases at reasonable reaction rates, while maintaining the cure behaviour and independent of functionality. Parallel chain-growth ene homopolymerization was considered negligible when compared with the main coupling route. However, the comonomer feed ratio had impact on the thermoset properties with high ene-density copolymers giving networks with higher glass transition temperature values (Tg) and a narrower distribution of cross-links than films with lower ene composition. The thiol–ene systems evaluated in this study serve as model example for the sustainable use of naturally-occurring 1,2-disubstituted alkenes at making semi-synthetic polymeric materials in high conversions with a range of properties in an environment-friendly way.

  • 161.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Thiol-ene coupling of 1,2-disubstituted alkene monomers: The kinetic effect of cis/trans-isomer structures2010In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 46, no 12, p. 2321-2332Article in journal (Refereed)
    Abstract [en]

    The free-radical induced reaction between a tri-functional thiol (2-ethyl-(hydroxymethyl)-1,3-propanediol trimercapto propionate) and two 1,2-disubstituted alkenes (methyl oleate and methyl elaidate) has been investigated under photochemical conditions. The photoreaction was monitored via time-resolved FUR, Raman and NMR spectroscopy to provide insights about the kinetics and efficiency in end-product formation. The information collected was subjected to numerical modelling using the GEPASI software using pre-established literature values for the rate coefficients in order to verify the proposed reaction scheme. The results confirm the thiol-ene reaction mechanism showing a very fast cis/trans-isomerization (<1.0 min) when compared with the total disappearance of unsaturations, indicating that the rate-limiting step controlling the reaction is the hydrogen transfer from the thiol involved in the formation of product. High thiol-ene conversions can be obtained at reasonable rates without major influence of side-reactions when performed in bulk indicating that this reaction is suitable for network forming purposes with mono-unsaturated fatty acid methyl esters derivatives. The kinetic and mechanistic information collected provides a basis for the design of new thiol-ene systems aiming at material and coating applications.

  • 162.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Mathevet, Jeanne-Marie
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Bringing D-limonene to the scene of bio-based thermoset coatings via free-radical thiol-ene chemistry: macromonomer synthesis, UV-curing and thermo-mechanical characterization2014In: Polymer Chemistry, ISSN 1759-9954, Vol. 5, no 9, p. 3245-3260Article in journal (Refereed)
    Abstract [en]

    The increasing pursuit for bio-based plastic materials led us to investigate the potential use of the monoterpene limonene in thermoset synthesis using the free-radical mediated thiol-ene reaction. The high efficiency of this reaction to prepare multifunctional ene-terminated resins, as intermediary macromolecular precursors, for thermosets synthesis was demonstrated under thermal and photoinitiated conditions. Although an excess of terpene favors formation of well-defined macromonomers in organic solution, the characteristic low-vapor pressure of limonene hinders its simple removal (or recycling) via evaporation after synthesis. Alteration to an initial thiol-ene stoichiometry of 1 : 0.5 enables production of high molecular weight resins in the form of 'hyperbranched oligomeric-like' structures having moderate polydispersity. UV-curing of these polyfunctional resins combined with equal mole compositions of multifunctional alkyl ester 3-mercapto propionates yields highly sticky, amorphous and flexible elastomers with different thermo-mechanical properties. These can be further modulated by varying the amount of unreacted thiol occluded within the networks working as a plasticizer. Introduction of a renewable cycloaliphatic structure into the materials offers a convenient way to enhance the glass-transition temperature and stiffness of traditional thiol-ene networks. The materials synthesized may be considered potentially useful as sealants and adhesives in a wide variety of applications including organic coatings. The versatility of UV-irradiation over thermal initiation makes this method particularly suitable for green industrial synthesis processes via thiol-ene chemistry using limonene and multifunctional thiols. The thiol-ene system evaluated herein serves as a model example for the sustainable incorporation of natural diolefinic monomers into semisynthetic thiol-ene networks exhibiting a range of thermo-mechanical properties.

  • 163.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    van der Meulen, Inge
    Eindhoven University of Technology, Laboratory of Polymer Chemistry, Eindhoven, The Netherlands.
    Trey, Stacy
    SP Trätek, SP Technical Research Institute of Sweden, Stockholm.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Heise, Andreas
    Eindhoven University of Technology, Laboratory of Polymer Chemistry, Eindhoven, The Netherlands.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Photoinduced thiol-ene cross-linking of globalide/ε-caprolactone copolymers: curing performance and resulting thermoset properties2012In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 50, no 1, p. 16-24Article in journal (Refereed)
    Abstract [en]

    The increasing demand for bioderived polymers led us to investigate the potential use of the macrolactone globalide in thermoset synthesis via the photoinduced thiolene reaction. A series of six lipase-catalyzed poly(globalide-caprolactone) copolyesters bearing internal main-chain unsaturations ranging from 10 to 50 and 100 mol % were successfully crosslinked in the melt with equal amounts of thiol groups from trimethylolpropane-trimercapto propionate affording fully transparent amorphous elastomeric materials with different thermal and viscoelastic properties. Three major conclusions can be drawn from this study: (i) high thiol-ene conversions (> 80%) were easily attained for all cases, while maintaining the cure behavior, and irrespective of functionality at reasonable reaction rates; (ii) parallel chain-growth homopropagation of the ene monomer is insignificant when compared with the main thiolene coupling route; and (iii) high ene-density copolymers result in much lower extracted sol fractions and high T(g) values as a result of a more dense and homogeneous crosslinked network. The thiol-ene system evaluated in this contribution serve as model example for the sustainable use of naturally occurring 1,2-disubstituted alkenes in making semisynthetic polymeric materials in high conversions with a range of properties.

  • 164. Cozzolino, C. A.
    et al.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Iotti, M.
    Sacchi, B.
    Piga, A.
    Farris, S.
    Exploiting the nano-sized features of microfibrillated cellulose (MFC) for the development of controlled-release packaging2013In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 110, p. 208-216Article in journal (Refereed)
    Abstract [en]

    Microfibrillated cellulose (MFC) was used in this study to prepare films containing an active molecule, lysozyme, which is a natural antimicrobial agent. The main goal of this research was to assess the potential for exploiting the nano-sized dimension of cellulose fibrils to slow the release of the antimicrobial molecule, thus avoiding a too-quick release into the surrounding medium, which is a major disadvantage of most release systems. For this purpose, the release kinetics of lysozyme over a 10-day period in two different media (pure water and water/ethanol 10. wt.%) were obtained, and the experimental data was fitted with a solution of Fick's second law to quantify the apparent diffusion coefficient (D). The results indicate that the MFC retained lysozyme, presumably due to electrostatic, hydrogen, and ion-dipole interactions, with the largest release of lysozyme-approximately 14%-occurring from the initial amount loaded on the films. As expected, ethanol as a co-solvent slightly decreased the diffusion of lysozyme from the MFC polymer network. The addition of two potential modulating release agents-glycerol and sodium chloride-was also evaluated. Findings from this work suggest that MFC-based films can be considered a suitable candidate for use in controlled-release packaging systems.

  • 165.
    Cozzolino, Carlo A.
    et al.
    University of Sassari.
    Blomfeldt, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Piga, Antonio
    University of Sassari.
    Piergiovanni, Luciano
    Farris, Stefano
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Dye release behavior from polyvinyl alcohol films in a hydro-alcoholic medium: Influence of physicochemical heterogeneity2012In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 403, p. 45-53Article in journal (Refereed)
    Abstract [en]

    In this paper we investigated the release kinetics of a model drug-like compound (Coomassie brilliant blue) from polyvinyl alcohol (PVOH) films into a hydro-alcoholic solution as a function of the physicochemical properties of the polymer matrix. After 33 days of monitoring, the total amount released ranged from 10% for the high hydrolysis degree/low molecular weight PVOH films to 60% for the low hydrolysis degree/low molecular weight films. Mathematical modeling allowed for an estimation of the two diffusion coefficients (D 1 and D 2) that characterized the release profile of the dye from the films. The degree of hydrolysis dramatically affected both the morphology and the physical structure of the polymer network. A high hydroxyl group content was also associated with the shifting of second order and first order transitions toward higher temperatures, with a concurrent increase in crystallinity. Moreover, the higher the degree of hydrolysis, the higher the affinity of the polymer to the negatively charged molecule dye. Selection of the polymer matrix based on physicochemical criteria may help in achieving different release patterns, thereby representing the first step for the production of polymer systems with modulated release properties.

  • 166.
    Cranston, Emily D.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Eita, Mohamed
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Johansson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Netrval, Julia
    Salajkova, Michaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Arwin, Hans
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Determination of Young's Modulus for Nanofibrillated Cellulose Multilayer Thin Films Using Buckling Mechanics2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 4, p. 961-969Article in journal (Refereed)
    Abstract [en]

    The Young's modulus of multilayer films containing nanofibrillated cellulose (NFC) and polyethyleneimine (PEI) was determined Using the strain-induced elastic buckling instability for mechanical measurements (SLEBIMM) technique.(1) Multilayer films were built up on polydimethylsiloxane substrates using electrostatic layer-by-layer assembly. At 50% relative humidity, SIEBIMM gave a constant Young's modulus of 1.5 +/- 0.2 GPa for 35-75 run thick films. Conversely, in vacuum, the Young's modulus was 10 times larger, at 17.2 +/- 1.2 GPa. A slight decrease in buckling wavelength with increasing strain was observed by scanning electron microscopy with in situ compression, and above 10% strain, extensive cracking parallel to the compressive direction occurred. We conclude that whereas PEI acts as a "glue" to hold multiple layers of NFC together, it prevents full development of hydrogen bonding and specific fibril-fibril interactions, and at high humidity, its hygroscopic nature decreases the elastic modulus when compared with pure NFC films.

  • 167. Cunha, Ana G.
    et al.
    Lundahl, Meri
    Ansari, Mohd Farhan
    Johansson, Leena-Sisko
    Campbell, Joseph M.
    Rojas, Orlando J.
    Surface Structuring and Water Interactions of Nanocellulose Filaments Modified with Organosilanes toward Wearable Materials2018In: ACS APPLIED NANO MATERIALS, ISSN 2574-0970, Vol. 1, no 9, p. 5279-5288Article in journal (Refereed)
    Abstract [en]

    Colloidal dispersions of cellulose nanofibrils (CNFs) are viable ternatives to cellulose II dissolutions used for filament spinning. e porosity and water vapor affinity of CNF filaments make them itable for controlled breathability. However, many textile plications also require water repellence. Here, we investigated the fects of postmodification of wet-spun CNF filaments via chemical vapor position (CVD). Two organosilanes with different numbers of methyl bstituents were considered. Various surface structures were achieved, ther as continuous, homogeneous coating layers or as ree-dimensional, hairy-like assemblies. Such surface features reduced e surface energy, which significantly affected the interactions with ter. Filaments with water contact angles of up to 116 were obtained, d surface energy measurements indicated the possibility of developing phiphobicity. Dynamic vapor sorption and full immersion experiments re carried out to inquire about the interactions with water, whether the liquid or gas forms. Mechanical tests revealed that the wet rength of the modified filaments were almost 3 times higher than that the unmodified precursors. The hydrolytic and mechanical stabilities the adsorbed layers were also revealed. Overall, our results shed ght on the transformation of aqueous dispersions of CNFs into laments that are suited for controlled interactions with water via ncurrent hydrolysis and condensation reactions in CVD, while intaining the moisture buffering capacity and breathability of related ructures.

  • 168.
    Dabbagh, Sandra
    KTH, School of Chemical Science and Engineering (CHE).
    Oxidative Degradation of Polyether In Contact with Minerals2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Oxidative degradation of adhesives based on silane terminated polypropylene oxide and polypropylene oxide (PPO) was studied. The combination of rapeseed oil and PPO as plasticizer in the parquet adhesive gave rise to oxidative degradation in contact with screeds of certain minerals. In order to investigate the degradation process in parquet adhesive two experimental approaches were employed in parallel. The first method was ageing of a solid adhesive-screed system at elevated temperature. It was done in order to evaluate the effect of contact between adhesives and screed in different adhesive-screed systems. Another purpose was also to identify the degradation procedure in a system resembling reality. The second method used was ageing of a soluble mixture of pure PPO with selected plant oils; in order to study the affect of oils unsaturations on the PPO by FTIR.

    FTIR was used to monitor the degradation of samples after different exposure periods. Unfortunately, interference from the adhesive additives made monitoring of the degradation process difficult in this approach. On the other hand, the optical inspection of the samples degradation process gave a clearer overview. A second method, looking only at two components mixed e.g. PPO and Oil, gave clear FTIR spectra showing that the oxidation process of rapeseed oil started in the period before fifteen days ageing at 75 oC.

    The combination of FTIR and optical inspection gave a clear image of the adhesive degradation process. Interaction between unsaturated carboxylic acid in the vegetable oils and PPO can increase the degradation rate of parquet adhesives by a radical mechanism. Another parameter affecting the degradation is the interfacial interaction between adhesive containing PPO-Rapeseed oil as plasticizer and screed with high alkalinity, porosity and humidity. The alkaline and humid conditions in the screed probably increase the hydrolysis of rapeseed oil. Further, the porosity of the screed provides a large surface area enabling the plasticizer to be exposed to plenty of oxygen from the air. Therefore, the plasticizer is not only exposed to hydrolysis but also oxidation. This would support the observation of migration of the rapeseed oil, since it is known that carboxylic acid has affinity to calcium sulfate anhydrite in the screed material. Migration and oxidation of rapeseed oils carboxylic acid generate radicals, which accelerate the degradation of PPO in the adhesive film. This process correlated with disappearance of PPO absorbance band from the spectrum.

  • 169.
    Das, Oisik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Prakash, Chaitra
    Univ Auckland, Ctr Adv Composite Mat, Dept Mech Engn, Auckland 1142, New Zealand..
    Lin, Richard J. T.
    Univ Auckland, Ctr Adv Composite Mat, Dept Mech Engn, Auckland 1142, New Zealand..
    Nanoindentation and flammability characterisation of five rice husk biomasses for biocomposites applications2019In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 125, article id UNSP 105566Article in journal (Refereed)
    Abstract [en]

    Five different rice husks (RHs) having different geographical origins were characterised for their mechanical and fire reaction properties using nanoindentation and cone calorimetry, respectively. Analyses relating to ash and extractives contents, density and morphologies were also performed. The RHs had statistically similar extractives content, nanoindentation properties and peak heat release rates (PHRRs). The polypropylene-based composites made from these RHs also had insignificant differences in their tensile moduli, elongation and PHRR values. The RH inclusion conserved the tensile/flexural strengths while enhancing the moduli of the composites, as compared to the neat polypropylene. The material characteristics being ubiquitous amongst the different RH types enable the creation of biocomposites with foreseeable performance properties. Moreover, the individual nanoindentation and fire reaction properties of the RI-Is allowed the presaging of the bulk biocomposites' properties using theoretical models. Good agreements between predicted and experimental moduli/PHRRs were achieved using rule of mixtures and Halpi-Pegano models.

  • 170.
    Das, Oisik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Rasheed, Faiza
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Kim, Nam Kyeun
    Univ Auckland, Dept Mech Engn, Ctr Adv Composite Mat, Auckland, New Zealand..
    Johansson, Eva
    Swedish Univ Agr Sci, Fac Landscape Planning Hort & Crop Prod Sci, Dept Plant Breeding, S-23053 Alnarp, Sweden..
    Capezza, Antonio Jose
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Kalamkarov, Alexander L.
    Dalhousie Univ, Dept Mech Engn, Halifax, NS B3H 4R2, Canada..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Polymer Mat Div, Dept Fibre & Polymer Technol, S-10044 Stockholm, Sweden..
    The development of fire and microbe resistant sustainable gluten plastics2019In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 222, p. 163-173Article in journal (Refereed)
    Abstract [en]

    This study shows the improvement of fire and microbe resistance of sustainable (protein) plastics (i.e. wheat gluten, WG), by using triethylene glycol diamine and dialdehyde. In addition, an anti-microbial agent (lanosol) was also used separately and in combination with the diamine/dialdehyde. The network formed by the diamine and dialdehyde, during the production of compression-moulded plates, resulted in high fire performance index, large amount of char and low thermal decomposition rate. The best fire resistance was obtained by the combination of the dialdehyde and lanosol, which also yielded a char with the intact surface. The peak-heat-release-rate of this material was only 38% of that of the pure gluten material. This material also showed anti-bacterial (E. coli) properties. However, the diamine was more effective than the combination of dialdehyde/lanosol. Gluten materials with diamine resisted mould growth during a 22 days test at a relative humidity of 100%. The gluten material with the lanosol applied to the sample surface resisted mould growth during a three-week test at both ambient temperature and 37 degrees C. Despite the relatively high contents of the difunctional reagents used (15 wt%), leading to an increased stiffness in most cases, only the network formed with glyoxal resulted in a decrease in water uptake as compared to the pure gluten material.

  • 171. Dax, Daniel
    et al.
    Soledad Chavez, Maria
    Xu, Chunlin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Process Chemistry Centre, C/o Laboratory of Wood and Paper Chemistry, Åbo Akademi University, Finland .
    Willfor, Stefan
    Teixeira Mendonca, Regis
    Sanchez, Julio
    Cationic hemicellulose-based hydrogels for arsenic and chromium removal from aqueous solutions2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 111, p. 797-805Article in journal (Refereed)
    Abstract [en]

    In this work the synthesis of hemicellulose-based hydrogels and their application for the removal of arsenic and chromium ions is described. In a first step O-acetyl galactoglucomannan (GGM) was subjected to a transesterification applying glycidyl methacrylate (GMA) for the synthesis of novel GGM macromonomers. Two distinguished and purified GGM fractions with molar mass of 7.1 and 28 kDa were used as starting materials. The resulting GGM macromonomers (GGM-MA) contained well-defined amounts of methacrylate groups as determined by H-1 NMR spectroscopy. Selected GGM-MA derivatives were consecutively applied as a crosslinker in the synthesis of tailored hydrogels using [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA) as monomer. The swelling rate of the hydrogels was determined and the coherence between the swelling rate and the hydrogel composition was examined. The morphology of the GGM-based hydrogels was analysed by SEM and the hydrogels revealed a high surface area and were assessed in respect to their ability to remove arsenate and chromate ions from aqueous solutions. The presented bio-based hydrogels are of high interest especially for the mining industries as a sustainable material for the treatment of their highly contaminated wastewaters.

  • 172. Dax, Daniel
    et al.
    Xu, Chunlin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Langvik, Otto
    Hemming, Jarl
    Backman, Peter
    Willför, Stefan
    Synthesis of SET-LRP-Induced Galactoglucomannan-Diblock Copolymers2013In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 51, no 23, p. 5100-5110Article in journal (Refereed)
    Abstract [en]

    Polysaccharides are biorenewable and biodegradable starting materials for the development of functional materials. The synthesis of a monofunctional macroinitiator for single electron transfer-living radical polymerization was successfully developed from a wood polysaccharide-O-acetyl galactoglucomannan (GGM) using a beforehand synthesized amino-functional -bromoisobutyryl derivative applying reductive amination. The GGM macroinitiator was employed to initiate a controlled radical polymerization of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA), methyl methacrylate (MMA), and N-isopropylacrylamide (NIPAM) using Cu-0/Me-6-Tren as a catalyst. The either charged or amphiphilic GGM-b-copolymers with different chain lengths of the synthetic block were successfully synthesized without prior hydrophobization of the GGM chain and dimethyl sulfoxide (DMSO) or DMSO/water mixtures were used as solvents. This novel synthetic approach may find untapped potentials particularly for the development of polysaccharide-based amphiphilic additives for cosmetics or paints and for the design of novel temperature or pH responsive polymers with such potential applications as in drug delivery systems or in biocomposites.

  • 173. de Francisco, Raquel
    et al.
    Tiemblo, Pilar
    Hoyos, Mario
    Gonzalez-Arellano, Camino
    Garcia, Nuria
    Berglund, 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.
    Synytska, Alla
    Multipurpose Ultra and Superhydrophobic Surfaces Based on Oligodimethylsiloxane-Modified Nanosilica2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, p. 18998-19010Article in journal (Refereed)
    Abstract [en]

    Nonfluorinated hydrophobic surfaces are of interest for reduced cost, toxicity, and environmental problems. Searching for such surfaces together with versatile processing, A200 silica nanoparticles are modified with an oligodimethylsiloxane and used by themselves or with a polymer matrix. The goal of the surface modification is controlled aggregate size and stable suspensions. Characterization is done by NMR, microanalysis, nitrogen adsorption, and dynamic light scattering. The feasibility of the concept is then demonstrated. The silica aggregates are sprayed in a scalable process to form ultrahydrophobic and imperceptible coatings with surface topographies of controlled nanoscale roughness onto different supports, including nanofibrillated cellulose. To improve adhesion and wear properties, the organosilica was mixed with polymers. The resulting composite coatings are characterized by FE-SEM, AFM, and contact angle measurements. Depending on the nature of the polymer, different functionalities can be developed. Poly(methyl methacrylate) leads to almost superhydrophobic and highly transparent coatings. Composites based on commercial acrylic car paint show "pearl-bouncing" droplet behavior. A light-emitting polyfluorene is synthesized to prepare luminescent and water repellent coatings on different supports. The interactions between polymers and the organosilica influence coating roughness and are critical for wetting behavior. In summary, the feasibility of a facile, rapid, and fluorine-free hydrophobization concept was successfully demonstrated in multipurpose antiwetting applications.

  • 174.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose degradation in the Vasa: The role of acids and rust2013In: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, Vol. 58, no 4, p. 308-313Article in journal (Refereed)
    Abstract [en]

    The oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron-rich surface wood differs from the interior wood in that it displays higher pH and cellulose with higher molecular weight. The objective of this study was to determine why there is a difference in cellulose degradation, pH, and oxalic acid amount between the surface region and the interior of the Vasa timbers. Analysis of cellulose weight average molecular weight by size exclusion chromatography was performed, as well as quantification of oxalic acid and iron by high-performance anion exchange chromatography and atomic emission spectroscopy, respectively. It was found that a decrease in iron content coincides with an increase in oxalic acid concentration and a drop in pH at a certain depth from the wood surface. When iron-rich surface wood samples from the Vasa were mixed with an aqueous solution of oxalic acid, a fast increase of pH over time was observed. Neither interior wood poor in iron nor the fresh oak reference showed the same neutralizing effect during the time of measurement. This indicates that the presence of iron (rust) causes a neutralization of the wood, through the formation of iron(III) oxalato complexes, thus protecting the wood from oxalic acid hydrolysis. This effect was not observed to the same extent for other acids observed in Vasa wood (sulfuric, formic, glycolic, and acetic acids).

  • 175.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Degradation reactions in vasa wood2011In: Shipwrecks 2011, 2011, p. 114-116Conference paper (Refereed)
  • 176.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    Sandberg, Teresia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Chemical analysis of wood extractives and lignin in the oak wood of the 380 year old Swedish warship Vasa2011Conference paper (Refereed)
    Abstract [en]

    In order to map the source of oxalic acid in the interior wood of the Vasa ship, an analysis of wood extractives (tannins) was conducted. Samples used for analysis were PEG-impregnated dry Vasa wood, waterlogged Vasa wood and a reference material (fresh oak). The wood material was ground and extracted with an acetone/water-mixture. In the reference sample, several types of tannins were found such as the isomers castalagin/vescalagin and grandinin and their dimmers roburin A/D and roburin B/C respectively. The results have been confirmed by NMR spectroscopy and MALDI-TOF. The interior of the waterlogged Vasa wood contained small amounts of monomers, whereas the dry, PEG treated Vasa revealed no discernible amounts of hydrolysable tannins or other easily soluble compounds. Furthermore, an analysis of lignin was made by means of chemical degradation (thioacidolysis). A decrease in the amount of β-O-4 bonds in the lignin structure would imply a formation of easily oxidized free phenolics. The products were analyzed by GC-MS, which revealed no dramatic differences between the Vasa samples and the reference. The results were confirmed by CP/MAS NMR by analyzing the differences in the aromatic region (150∼160 ppm) as well as the carbonyl region (190∼200 ppm).

  • 177.
    Dedic, Dina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sandberg, Teresia
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Iversen, Tommy
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Analysisof lignin and extractives in the oak wood of the 17th century warship Vasa2011Manuscript (preprint) (Other (popular science, discussion, etc.))
  • 178.
    Deming, Timothy J.
    et al.
    Univ Calif Los Angeles, Dept Bioengn, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Dept Chem & Biochem, Los Angeles, CA 90095 USA..
    Klok, Harm-Anton
    Ecole Polytech Fed Lausanne, Inst Mat, Batiment MXD,Stn 12, CH-1015 Lausanne, Switzerland.;Inst Sci & Ingn Chim, Lab Polymeres, Batiment MXD,Stn 12, CH-1015 Lausanne, Switzerland..
    Armes, Steven P.
    Univ Sheffield, Dept Chem, Dainton Bldg,Brook Hill, Sheffield S3 7HF, S Yorkshire, England..
    Becker, Matthew L.
    Univ Akron, Dept Polymer Sci, Akron, OH 44325 USA..
    Champion, Julie A.
    Georgia Inst Technol, Sch Chem & Biomol Engn, Atlanta, GA 30332 USA..
    Chen, Eugene Y. -X.
    Colorado State Univ, Dept Chem, Ft Collins, CO 80523 USA..
    Heilshorn, Sarah C.
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA..
    van Hest, Jan C. M.
    Eindhoven Univ Technol, Dept Biomed Engn, POB 513, NL-5600 MB Eindhoven, Netherlands.;Eindhoven Univ Technol, Dept Chem Engn & Chem, POB 513, NL-5600 MB Eindhoven, Netherlands..
    Irvine, Darrell J.
    MIT, Dept Mat Sci & Engn, Koch Inst Integrat Canc Res, Dept Biol Engn, Cambridge, MA 02139 USA..
    Johnson, Jeremiah A.
    MIT, Dept Chem, Program Polymers & Soft Matter, Cambridge, MA 02139 USA.;MIT, Koch Inst Integrat Canc Res, Cambridge, MA 02139 USA..
    Kiessling, Laura L.
    MIT, Dept Chem, 77 Massachusetts Ave, Cambridge, MA 02139 USA..
    Maynard, Heather D.
    Univ Calif Los Angeles, Dept Bioengn, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Dept Chem & Biochem, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Calif NanoSyst Inst, 570 Westwood Plaza, Los Angeles, CA 90095 USA..
    de la Cruz, Monica Olvera
    Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA.;Northwestern Univ, Dept Chem, 2145 Sheridan Rd, Evanston, IL 60208 USA.;Northwestern Univ, Dept Chem & Biol Engn, Evanston, IL 60208 USA.;Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA..
    Sullivan, Millicent O.
    Univ Delaware, Dept Chem & Biomol Engn, Newark, DE 19716 USA..
    Tirrell, Matthew V.
    Univ Chicago, Inst Mol Engn, Chicago, IL 60637 USA..
    Anseth, Kristi S.
    Univ Colorado, Dept Chem & Biol Engn, Boulder, CO 80309 USA.;Univ Colorado, BioFrontiers Inst, Boulder, CO 80309 USA..
    Lecommandoux, Sebastien
    Univ Bordeaux, CNRS, Bordeaux INP, LCPO,UMR 5629, 16 Ave Pey Berland, F-33600 Pessac, France..
    Percec, Simona
    Temple Univ, Dept Chem, Philadelphia, PA 19122 USA..
    Zhong, Zhiyuan
    Soochow Univ, Coll Chem Chem Engn & Mat Sci, Biomed Polymers Lab, Suzhou 215123, Peoples R China.;Soochow Univ, Coll Chem Chem Engn & Mat Sci, Jiangsu Key Lab Adv Funct Polymer Design & Applic, Suzhou 215123, Peoples R China..
    Albertsson, Ann-Christine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Polymers at the Interface with Biology2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 8, p. 3151-3162Article in journal (Other academic)
  • 179. Ditta, L. A.
    et al.
    Dahlgren, Björn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Sabatino, M. A.
    Dispenza, C.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    The role of molecular oxygen in the formation of radiation-engineered multifunctional nanogels2019In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 114, p. 164-175Article in journal (Refereed)
    Abstract [en]

    Nanogels are very promising biomedical nanodevices. The classic “radiation chemistry-based” approach to synthetize nanogels consists in the irradiation with pulsed electron beams of dilute, N 2 O-saturated, aqueous solutions of water-soluble polymers of the “crosslinking type”. Nanogels with controlled size and properties are produced in a single irradiation step with no recourse to initiators, organic solvents and surfactants. This paper combines experimental syntheses, performed with two e-beam irradiation setups and dose-ranges, starting from poly(N-vinyl pyrrolidone) solutions of various concentrations, both in N 2 O-saturated and air-saturated initial conditions, with the numerical simulations of the radiation chemistry of aqueous solutions of a radical scavanger exposed to the same irradiation conditions used in the experiments. This approach provides a methodology to predict the impact of system and irradiation conditions on the water radiation chemistry, which in turn affect the nanogel features in terms of molecular and physico-chemical properties. In particular, the crucial role of initial and transient concentration of molecular oxygen is revealed. This work also proposes a very simple and effective methodology to quantitatively measure the double bonds formed in the systems from disporportionation and chain scission reactions, competing with inter-/intra-molecular crosslinking.

  • 180.
    Dong, Qian
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    An experimental method to identify various oxygen species transported in oxides2007In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 306, no 1-2, p. 166-172Article in journal (Refereed)
    Abstract [en]

    Oxygen transport in oxides can take place in molecular, atomic and ionic form. An experimental method is described which separates the contributions of molecules, atoms and ions to the overall oxygen transport in oxides. The method comprises gas phase analysis and the use of oxygen isotopes O-16 and O-18. In the general case, exposure to non-equilibrated O-2 containing 60-70% O-18 is optimal to obtain the highest accuracy in the measurement. The method is exemplified by distinguishing non-ionic (molecular and atomic) oxygen transport from ionic oxygen transport in a commercial yttria-stabilized zirconia (YSZ) sample in the temperature range of 600-900 degrees C. There is approximately 35% molecular, 20% atomic transport and 45% ionic oxygen transport in YSZ at 600 degrees C. It is found that the fraction percent of non-ionic oxygen transport decreases with increasing temperature, and ionic oxygen transport increases sharply with increasing temperature.

  • 181.
    Dongfang, Li
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wood cellulose activation dissolution, and hydrophobization2015Doctoral thesis, comprehensive summary (Other academic)
  • 182.
    Du, Xueyu
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Deepening the insights of lignin structure: Lignin-carbohydrate complex (LCC) fractionation and characterization and Kraft lignin amination2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improvement of kraft pulping delignification efficiency and value-addition of industrial kraft lignin are two attractive topics. The proposal that delignification is deteriorated by the presence of lignin-carbohydrate complex (LCC) is still being debated. Therefore, it is theoretically and practically important to investigate various LCC structures from native wood and their changes during different treatments. Currently, however, there is no effective LCC fractionation method that could quantitatively isolate all LCC fractions and be applicable for all types of lignocellulosic materials. The fractionation should also be followed by comprehensive and reliable structural characterisation. Additionally the Kraft lignin has a heterogeneous structure and poor properties. Structural modification is therefore one possible solution for creating more economical benefits than the presently direct combustion for heat.

    In this work, an LCC fractionation method has been developed, which preserves original lignin and lignin-carbohydrate (LC) bonding structures and is nearly quantitative. It is universally applicable for hardwood, softwood or non-wood species. A whole set of subsequent analytical tools for the comprehensive elucidation of the different LCC fractions has also been established and applied. After applying the LCC fractionation and characterisation:

    1). spruce wood was found to consist of 49.5% glucan-lignin (GL), 30.9% glucomannan–lignin (GML) and 12.0% xylan–lignin (XL). Although the LC and lignin-lignin (LL) linkage signals could not be directly observed by a 400 MHz NMR instrument, these linkages have been clearly observed by a 600 MHz NMR instrument equipped with a cryogenic probe after enzymatic hydrolysis. The LC bondings include phenyl glycoside, benzyl ether and γ-ester. Based on the LL bond frequencies, GML is less condensed than XL.

    2). a general lignin biodegradation mechanism by the laccase-mediator system (LMS) has been proposed, which mainly involves Cα oxidation and Cα-Cβ bond cleavage of the lignin side chain and eventually aromatic ring cleavage. The LMS delignification efficiency depends largely on the species of the applied laccase and mediator. Some LMS has been proven to possess an obvious capacity for hexenuronic acid (HexA) removal. For Kraft pulp bleaching, there are potential benefits of various combinations among biological treatment (by LMS), non-oxidative chemical (by urea treatment, U), and mechanical treatment (by refining, R).

    In addition, it has been demonstrated in this work that the structures and properties of industrial softwood Kraft lignin (LignoBoost lignin) could largely be upgraded by amination via the Mannich reaction. With or without a phenolation pretreatment, the aminated lignins obtained are promising polycationic materials, especially in the application as colloidal suspensions. During this investigation of kraft lignin amination, NMR methods have been developed for the quantification of the N content introduced and for the deepened insights of the structural changes of the lignin. 

  • 183.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Rencoret, Jorge
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Del Rio, Jose C.
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Martinez, Angel
    Centro de Investigaciones Biologicas.
    Gutierrez, Ana
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Understanding Pulp Delignification by Laccase-Mediator Systems through Isolation and Characterization of Lignin-Carbohydrate Complexes2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 9, p. 3073-3080Article in journal (Refereed)
    Abstract [en]

    The effects and mechanism of pulp delignificabon by laccases in the presence of redox mediators have been investigated on unbleached eucalyptus kraft pulp treated with laccases from Pycnoporus cinnabarinus (PcL) and Myceliophthora thermophila (MtL) and 1-hydroxybenzotriazole (HBT) and methyl syringate (MeS) as mediators, respectively. Determination of the corrected kappa number in eucalyptus pulps after the enzymatic treatments revealed that the PcL-HBT system exhibited a more remarkable delignification effect than the MtL-MeS system. To obtain further insight, lignin-carbohydrate complexes were fractionated and subsequently characterized by nuclear magnetic resonance, thioacidolysis (followed by gas chromatography and size exclusion chromatography), and pyrolysis-gas chromatography-mass spectrometry (pyrolysis-GC-MS) analyses before and after the enzymatic treatments and their controls. We can conclude that the laccase mediator treatments altered the lignin structures in such a way that more lignin was recovered in the xylan-lignin fractions, as shown by Klason lignin estimation, with smaller amounts of both syringyl (5) and guaiacyl (G) uncondensed units, as shown by thioacidolysis and gas chromatography, especially after the PcL-HBT treatment. The laccase mediator treatment produced oxidation at C alpha and cleavage of C alpha and C beta bonds in pulp lignin, as shown by pyrolysis-GC-MS. The general mechanism of residual lignin degradation in the pulp by laccase-mediator treatments is discussed in light of the results obtained.

  • 184.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Modification of industrial softwood kraft lignin using Mannich reaction with and without phenolation pretreatment2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 52, p. 729-735Article in journal (Refereed)
    Abstract [en]

    The amination of industrial softwood kraft lignin was conducted using the Mannich reaction to modify the lignin structure for value-added applications. To understand the reaction mechanism and to quantify the amount of amine groups that were introduced, different types of NMR analyses were performed. The lignin was also pretreated by phenolation to increase its reactivity and the amount of the amine groups that were introduced. The Mannich reaction was very selective at the C-5 position of the guaiacyl units and complete under acidic conditions with similar to 11-fold amounts of reagents of dimethylamine and formaldehyde over either model lignin (4-hydroxy-3-methoxyacetophenone, HMAP) or industrial spruce kraft lignin (LignoBoost lignin, LBL). For LBL, 28 amine groups were introduced over 100 aromatic rings. By weight, the nitrogen content was 2.5%. The animated lignin was found to possess a higher molecular mass, reaching a Mp of 4.9 x 10(3) Da compared to the original 319 x 10(3) Da, and with a considerably increased dispersibility, especially in a dilute aqueous solution of hydrochloric acid (pH = 3), namely 5.2 mg/ml. With a preceding phenolation treatment, which increased the amount of phenolic aromatic rings available for the Mannich reaction, an introduction of 42 amine groups over 100 aromatic rings, or a nitrogen content of 4.8%, was obtained, which caused a further increase of the molecular mass to 5.1 x 10(3) Da (Mp) and of dispersibility in the aqueous solution of hydrochloric acid up to 32.0 mg/ml. The aminated lignins with or without the phenolation pretreatment formed very stable colloidal suspensions in water, with large particle sizes (391 and 39 nm), high zeta potentials (31.6 and 27.2 mV), and large charge densities (1.6 and 1.2 x 10(-7) equiv./ml, respectively). The potential value-added applications of these modified lignins with high amine contents include use as surfactant chemicals, polycationic materials and slow-release fertilisers, among others.

  • 185.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Perez Boada, Marta
    Centro de Investigaciones Biologicas.
    Rencoret, Jorge
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Martinez, Angel
    Centro de Investigaciones Biologicas.
    Gutierrez, Ana
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Lignin-carbohydrate and lignin-lignin linkages in different lignin-carbohydrate complexes from spruce woodManuscript (preprint) (Other academic)
    Abstract [en]

    In order to characterize lignin-carbohydrate (LC) and lignin-lignin (LL) linkages in different lignin-carbohydrate complexes (LCCs), the glucan-lignin (GL), glucomannan-lignin (GML) and xylan-lignin (XL) isolated from spruce wood have been enzymatically hydrolyzed, using endoglucanase plus b-glucosidase (for GL and GML) or xylanase (for XL), followed by 2D HSQC NMR and Py-GC/MS analysis. It has been found that the enzymatic hydrolysis removed effectively most of the polysaccharide parts in the LCCs and thus enriched the lignin contents and LCC linkages so that various LC and LL linkages could be well demonstrated by the 2D HSQC NMR analysis. Three typical LC linkages, i.e. benzyl ether, γ-ester and phenyl glycoside, have been directly observed in the enzymatically hydrolyzed GML (En-GML) and enzymatically hydrolyzed XL (En-XL). There are two types of benzyl ether linkages, with primary and secondary OH from carbohydrates. There are three types of carbohydrate units linked with lignin by the phenyl glycoside bonds in the En-GML while only one type is found in the En-XL. It seems that mannose and galactose are among the sugar units involved in the linkages since their relative amounts in the sugar compositions increased after the enzymatic hydrolysis. From the LL linkages observed in the 2D HSQC NMR spectra, it was revealed that the lignin existing in GML is less condensed than the lignin from XL due to a higher percentage of β-O-4 sub-structure found in the former (75 % vs. 66 %). On the other hand, more other substructures have been found present in the lignin from XL than GML, e.g. phenylcoumaran (17 % vs. 15 %), dibenzodioxocin (9 % vs. 5 %), resinol (11 % vs. 6 %), and spirodienone (2 % vs. 1 %), implying more condensed lignin structures present in the XL. From the Py-GC/MS analysis, the relative amounts of guaiacol and coniferyl alcohol fragments over the acetoguaiacone fragment, an internal marker, were largely increased after the enzymatic hydrolysis, supporting the presences of even higher amounts of the phenyl glucoside LC linkages in the original LCCs since some of the linkages should have been cleaved during the enzymatic hydrolysis. The NMR analysis of the En-GL was not successful probably due to the attachment of the enzymes onto the GL structure or the existence of the remained crystalline cellulose structures.

  • 186. Dukette, Tiffany E
    et al.
    Mackay, Michael E
    Van Horn, Brooke
    Wooley, Karen L
    Drockenmuller, Eric
    Malkoch, Michael
    Hawker, Craig J
    Conformation of intramolecularly cross-linked polymer nanoparticles on solid substrates2005In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 5, no 9, p. 1704-1709Article in journal (Refereed)
    Abstract [en]

    The conformation of cross-linked, monomolecular, polystyrene nanoparticles on a solid substrate is considered as a function of cross-linking degree and substrate surface free energy. It is found that an extreme amount of cross-linking is necessary for the ca. 5-10 nm diameter nanoparticles to retain their original spherical shape, regardless of surface free energy. A lesser amount of cross-linking produces a nanoparticle that collapses to a pancake-like conformation on a high-energy substrate yet remains spherical on a low-energy surface. A simple model is developed to reveal the relationship between nanoparticle modulus and surface free energy to define the nanoparticle conformation.

  • 187.
    Duval, Antoine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Univ Roma Tor Vergata.
    Lange, Heiko
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Crestini, Claudia
    Modification of Kraft Lignin to Expose Diazobenzene Groups: Toward pH- and Light-Responsive Biobased Polymers2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 9, p. 2979-2989Article in journal (Refereed)
    Abstract [en]

    A pH- and light-responsive polymer has been synthesized from softwood kraft lignin by a two-step strategy that aimed to incorporate diazobenzene groups. Initially, styrene oxide was reacted with the phenolic hydroxyl groups in lignin, to offer the attachment of benzene rings, thus creating unhindered reactive sites for further modifications. The use of advanced spectroscopic techniques H-1 and P-31 NMR, UV and FTIR) demonstrated that the reaction was quantitative and selective toward the phenolic hydroxyl groups. In a second step, the newly incorporated benzene rings were reacted with a diazonium cation to form the target diazobenzene motif, whose formation was again thoroughly verified. As anticipated, the diazobenzene-containing kraft lignin derivatives showed a pH-dependent color change in solution and light-responsive properties resulting from the cis-trans photoisomerization of the diazobenzene group.

  • 188.
    Dånmark, Staffan
    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.
    Patarroyo, Manuel
    Institutionen for Odontologi, Karolinska Institute.
    Mustafa, Kamal
    Insititutt for klinisk Odontologi, Medicinska och Odontologiska Fakulteten, Universitetet i Bergen, Norge.
    Integrin-mediated adhesion of human mesenchymal stem cells to extracellular matrix proteins adsorbed to polymer surfaces2012In: Biomedical Materials, ISSN 1748-6041, E-ISSN 1748-605X, Vol. 7, no 3, p. 035011-Article in journal (Refereed)
    Abstract [en]

    In vitro, degradable aliphatic polyesters are widely used as cell carriers for bone tissue engineering, despite their lack of biological cues. Their biological active surface is rather determined by an adsorbed layer of proteins from the surrounding media. Initial cell fate, including adhesion and proliferation, which are key properties for efficient cell carriers, is determined by the adsorbed layer of proteins. Herein we have investigated the ability of human bone marrow derived stem cells (hBMSC) to adhere to extracellular matrix (ECM) proteins, including fibronectin and vitronectin which are present in plasma and serum. hBMSC expressed integrins for collagens, laminins, fibronectin and vitronectin. Accordingly, hBMSC strongly adhered to these purified ECM proteins by using the corresponding integrins. Although purified fibronectin and vitronectin adsorbed to aliphatic polyesters to a lower extent than to cell culture polystyrene, these low levels were sufficient to mediate adhesion of hBMSC. It was found that plasma- and serum-coated polystyrene adsorbed significant levels of both fibronectin and vitronectin, and fibronectin was identified as the major adhesive component of plasma for hBMSC; however, aliphatic polyesters adsorbed minimal levels of fibronectin under similar conditions resulting in impaired cell adhesion. Altogether, the results suggest that the efficiency of aliphatic polyesters cell carriers could be improved by increasing their ability to adsorb fibronectin.

  • 189.
    Dånmark, Staffan
    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.
    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.
    Mustafa, Kamal
    Insititutt for klinisk Odontologi, Medicinska och Odontologiska Fakulteten, Universitetet i Bergen, Norge.
    Enhanced Osteoconductivity of Degradable co-Polyester Scaffolds through Covalent Immobilization of BMP-2Manuscript (preprint) (Other academic)
  • 190.
    Dånmark, Staffan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gladnikoff, Micha
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Zelenina, Marina
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Mustafa, Kamal
    Insititutt for klinisk Odontologi, Medicinska och Odontologiska Fakulteten, Universitetet i Bergen, Norge.
    Russom, Aman
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Development of Novel Microfluidic Device for Long-Term in situ Monitoring of Live Cells in 3-dimensional MatricesManuscript (preprint) (Other academic)
  • 191.
    Edlund, Ulrica
    KTH, Superseded Departments, Polymer Technology.
    Design of new biodegradable polymer matrices for controlled drug delivery2000Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Conventional drug administration technologies display poorcontrollability, and lead to high plasma concentrations andshort duration times, which frequently lead to adverse effects.Controlled release technology aims at predictable andreproducible delivery of an active substance over an extendedperiod of time, yielding optimal response and prolongedefficiency, and thus offering considerable improvement of manytreatments. A powerful approach to controlled drug delivery isthe incorporation of the drug into a biodegradable polymericmatrix, which distributes the active substance in a controlledand sustained fashion as the polymer erodes.

    This thesis describes the design of novel biodegradablepolymer matrices for controlled and sustained drug delivery.New functional and biodegradable materials with variableproperties were obtained by homopolymer blending andcopolymerization of building blocks with specific, desirableproperties; poly(adipic anhydride) (PAA), poly(trimethylenecarbonate) (PTMC), poly(1,5-dioxepan-2-one) (PDXO),poly(L-lactide) (PLLA), poly(D,L-lactide) (PDLLA), andpoly(L-lactide-co-1,5-dioxepan-2-one) (P(L-LA-co-DXO).Techniques were developed for the preparation of drug-releasingmatrices in the form of films and microspheres. Variousanalysis techniques, including Differential ScanningCalorimetry,1H-Nuclear Magnetic Resonance, InfraredSpectrometry, Scanning Electron Microscopy, Size ExclusionChromatography and UV-VIS Spectroscopy, were used forcharacterization.

    Microspheres encapsulating therapeutic substances wereprepared from P(L-LA-co-DXO) and blends of PDXO with PLLA orPDLLA. The properties, storage stability,degradation and drugrelease characteristics of these matrices were explored,compared and evaluated with special regard to the morphologyand its impact on thein vitrobehavior. Sustained release of drugs wasobtained. The mode of release was strongly influenced by thehydrophilicity of the drug, and by the copolymer/blendcomposition and morphology. The lactide:DXO composition wasproven to be a versatile tool to control the morphology and inturn the rates and pattern of erosion and diffusion ofencapsulated agents from the matrices.

    Films were prepared from PTMC-PAA blends, in which PAA actedas a plasticizer. Loss of the fast-degrading PAA componentenhanced the porosity and hydration of the slow-degrading PTMC.A statistical full factorial model was designed to elucidatethe influence of matrix parameters and their interactions. ThePTMC-PAA ratio, the molecular weight of the PTMC, andinteractions amongst these factors significantly influenced therelease performance, mass loss and degree of plasticization andthe relationships obtained enabled the erosion and drug releasepattern to be predicted and controlled. Moisture uptake,storage stability at different relative humidities, and thesterilizability were determined to further explore theversatility of PTMC-PAA matrices. Thein vivolocal tissue response and biocompatibility ofPTMC-PAA implants was assessed in the anterior chamber ofrabbits eyes for 1 month. PTMC-rich matrices displayed goodbiocompatibility.

    Key factors that regulate the biological activity of thesepolymeric vehicles were identified as drug solubility,composition, molecular weight, stereochemical configuration,and morphology. By careful design, the degradation and drugrelease characteristics, e.g. kinetics and duration, can bealtered over a broad spectrum. This study shows that structuralchanges of the polymer backbone, and the modeling ofcomposition and morphology provide powerful means of tailoringsystems for specific applications.

    Keywords: controlled release, drug delivery, microspheres,polylactide, poly(1,5-dioxepan-2-one), poly(adipic anhydride),poly(trimethylene carbonate), degradation, blends

  • 192.
    Edlund, Ulrica
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Copolymerization and polymer blending of trimethylene carbonate and adipic anhydride for tailored drug delivery1999In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 72, no 2, p. 227-239Article in journal (Refereed)
    Abstract [en]

    The copolymerization in bulk and solution of trimethylene carbonate (TMC) with adipic anhydride (AA) as well as the blending of homopolymers are described. We show experimentally that the components are not copolymerizable but partially miscible, forming a microscopic dispersion without any visible signs of phase separation. Poly(adipic anhydride) (PAA) functions as a plasticizer, permitting an increase in the erosion rate by increasing the porosity and hydration. Drug delivery from the blends was evaluated. A statistical factorial model was designed to explore the influence of three important blend parameters and their interactions, making it possible to predict the erosion and drug-release behavior of the blend matrices. The PAA:poly(trimethylene carbonate) (PTMC) ratio and molecular weight of the polycarbonate component significantly influence the drug-release performance, mass loss, and degree of plasticization. The interaction among these factors also influences the blend properties. Plasticization of PTMC enhances the drug release to an extent that is dependent on the amount of PAA used. We demonstrate that blending offers a convenient alternative to copolymerization for the preparation of polymer matrices with predictable drug delivery.

  • 193.
    Edlund, Ulrica
    et al.
    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.
    Green living radical polymerization from hemicellulose-based macroinitiators2012In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 244Article in journal (Other academic)
  • 194.
    Edlund, Ulrica
    et al.
    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.
    Macroinitiator Halide Effects in Galactoglucomannan-Mediated Single Electron Transfer-Living Radical Polymerization2011In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 49, no 19, p. 4139-4145Article in journal (Refereed)
    Abstract [en]

    Chloro (Cl)- and bromo (Br)-functionalized macroinitiators were successfully prepared from the softwood hemicellulose O-acetylated galactoglucomannan (AcGGM) and then explored and evaluated with respect to their ability and efficiency of initiating single electron transfer-living radical polymerization (SET-LRP). Both halogenated species effectively initiate SET-LRP of an acrylate and a methacrylate monomer, respectively, yielding brushlike AcGGM graft copolymers, where the molecular weights are accurately controlled via the monomer:macroinitiator ratio and polymerization time over a broad range: from oligomeric to ultrahigh. The nature of the halogen does not influence the kinetics of polymerization strongly, however, for acrylate graft polymerization, AcGGM-Cl gives a somewhat higher rate constant of propagation, while methacrylate grafting proceeds slightly faster when the initiating species is AcGGM-Br. For both monomers, the macroinitiator efficiency is superior in the case of AcGGM-Br.

  • 195.
    Edlund, Ulrica
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Microspheres from poly(D,L-lactide)/poly(1,5-dioxepan-2-one) miscible blends for controlled drug delivery2000In: Journal of bioactive and compatible polymers (Print), ISSN 0883-9115, E-ISSN 1530-8030, Vol. 15, no 3, p. 214-229Article in journal (Refereed)
    Abstract [en]

    Novel biodegradable microspheres were designed from blends of poly(D,L-lactide) (PDLLA) and poly(1,5-dioxepan-2-one) (PDXO). The addition of PDXO to PDLLA yielded a more pliable and versatile matrix, where the properties can be controlled by means of composition. The components were fully miscible and formed homogeneous, amorphous, smooth and dense microspheres. Blend composition was a vital factor in determining the blend properties, morphology and in vitro degradation. Diclofenac sodium, a non-steroidal anti-inflammatory drug, was incorporated into PDLLA-PDXO microspheres of various composition ratios. Sustained release of drug was obtained. The degradation and release rates of PDLLA-PDXO microspheres were dependent on the blend composition, providing a powerful means of controlling drug delivery.

  • 196.
    Edlund, Ulrica
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Morphology engineering of a novel poly(L-lactide)/poly(1,5-dioxepan-2-one) microsphere system for controlled drug delivery2000In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 38, no 5, p. 786-796Article in journal (Refereed)
    Abstract [en]

    Morphology is presented as a powerful tool to control the in vitro degradation and drug release characteristics of novel drug delivery microspheres prepared from homopolymer blends of 1,5-dioxepan-2-one, DXO, and L-lactide, L-LA. Their performance in this respect was compared to analogous P(L-LA-co-DXO) microspheres. Blends formed denser and less porous microspheres with a higher degree of matrix crystallinity than copolymers of corresponding L-LA:DXO composition. The morphology differences of blends and copolymers, further adjustable by means of component ratio, are shown to have a vital impact on the in vitro performance. Sustained drug delivery was obtained from both copolymers and blends. Molecular weight; loss was retarded and diffusion-mediated release was inhibited in the latter case, further delaying the release process. The effects of storage on the physicochemical properties of these systems were evaluated under desiccated and moist conditions for 5 months. Storage-induced physicochemical changes, such as matrix crystallization and molecular weight decrease, were accelerated at higher relative humidities. P(L-LA-co-DXO) demonstrated higher moisture sensitivity than a PLLA-PDXO blend of corresponding composition. The more crystalline and dense morphology of blend microspheres may thus be considered an improvement of the storage stability.

  • 197.
    Edlund, Ulrica
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Novel drug delivery microspheres from poly(1,5-dioxepan-2-one-co-L-lactide)1999In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 37, no 12, p. 1877-1884Article in journal (Refereed)
    Abstract [en]

    Novel microspheres from copolymers of 1,5-dioxepan-2-one (DXO) and L-lactide (L-LA) were prepared by oil-in-water solvent evaporation and oil-in-oil solvent removal. The two preparation techniques were evaluated for sphere formulation and incorporation of two different drugs. Sustained release of these therapeutic substances was obtained. The consequences of altering the DXO : LA ratio, preparation method, and drug hydrophilicity were explored and identified as factors governing sphere quality, in vitro degradation, and drug release characteristics. We show that these relationships provide a powerful means of controlling the microsphere performance.

  • 198.
    Edlund, Ulrica
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Singh, K
    Fogelberg, I
    Lundgren, O
    Sterilization, storage stability and in vivo biocompatibility of poly(trimethylene carbonate)/poly(adipic anhydride) blends2000In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 21, no 9, p. 945-955Article in journal (Refereed)
    Abstract [en]

    Biodegradable blends of poly(trimethylene carbonate) (PTMC) and poly(adipic anhydride) (PAA) have been proven to be strong candidates for controlled drug delivery polymers in vitro. We now report on the stability, sterilizability and in vivo local tissue response of these matrices. Blend matrices were sterilized by beta-radiation or ethylene oxide gas treatment, stored at different times and temperatures, and analyzed for changes in physicochemical properties. Moisture uptake at different relative humidities and storage times was determined. Sterilization procedures induced hydrolysis of the matrices. Ethylene oxide gas sterilization had a significantly more marked effect upon the matrix properties than radiation treatment. The onset of degradation was reflected in a decrease of crystallinity and molecular weight along with a change of blend composition. A similar onset of matrix degradation was observed upon storage in air. The physicochemical properties of the blends were well preserved upon storage under argon atmosphere. Biocompatibility of PTMC/PAA implants was assessed in the anterior chamber of rabbits eyes for 1 month. At selected post-operative time points, aqueous humor was analyzed for white blood cells and the corneal thickness was measured. The results suggest good biocompatability of PTMC-rich matrices, whereas fast eroding PAA-rich matrices caused inflammatory responses, due to a burst release of degradation products.

  • 199.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Källrot, Martina
    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.
    Nano Patterened Covalent Surface Modification of Poly(ε-caprolactone)2005In: Israel Journal of Chemistry, ISSN 0021-2148, Vol. 45, no 4, p. 429-435Article in journal (Refereed)
    Abstract [en]

    Using our new vapor-phase grafting technique, we have simultaneously chemically and physically modified the surface of poly(e-caprolactone) (PCL) films. The substrates were covered with nano patterned silicone rubber stamps and subjected to UV irradiation in the presence of the solvent-free vapor phase of either N-vinyl pyrrolidone or maleic anhydride, and a photoinitiator, under reduced pressure. The treated films display a surface pattern of grafted channels of 450-nm width, as confirmed by AFM and SEM. The grafting was further verified with ATR-FTIR, and contact angle measurements show an increased wettability of the surfaces.

  • 200.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Källrot, Martina
    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.
    Single-Step Covalent Functionalization of Polylactide Surfaces2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 24, p. 8865-8871Article in journal (Refereed)
    Abstract [en]

    A single-step, nondestructive, and versatile technique for the grafting and chemical surface modification of biodegradable polymers such as polylacticle is described. The substrates are subjected to the vapor phase of any of three investigated vinyl monomers: acrylamide, maleic anhydride, and N-vinylpyrrolidone, and grafting is induced by photoinitiation of benzophenone under solvent free conditions. The modified surfaces exhibit higher wettability, and the grafting is verified by X-ray photoelectron spectroscopy, attenuated total reflection Fourier-transform IR, contact-angle measurements, and scanning electron microscopy. The graft-chain pendant groups remain functional and can subsequently be modified so that a tailor-made surface with desired properties may be achieved.

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