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  • 1.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. 831220-7585.
    Polycaprolactone  Nanocomposites Reinforced  with   Cellulose Nanocrystals  Surface - modified  via  Covalent  Grafting  or  Physical Adsorption - a Comparative studyManuscript (preprint) (Other academic)
  • 2.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. 831220-7585.
    RAFT/MADIX Polymerization of Vinyl Acetate on Cellulose Nanocrystals for Nanocomposite ApplicationsManuscript (preprint) (Other academic)
  • 3.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. 831220-7585.
    Surface Modification of Nanocellulose towards Composite Applications2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanocelluloses have attracted great interest during recent decades owing to their renewability, abundancy and remarkable physical and mechanical properties. The aim of this work was to investigate new strategies for surface modification and functionalization of nanocelluloses and their subsequent incorporation in polymer-host matrices.

    Nanocomposites of cellulose nanofibrils (CNF) and polycaprolactone (PCL) were produced by employing CNF nanopaper (NP) as a template and surface-initiated ring-opening polymerization (SI-ROP) of ε-caprolactone (ε-CL). SI-ROP of ε-CL from filter paper (FP) was also carried out for comparison. A larger amount of PCL was grafted from NP than from FP. The grafted NP had stronger mechanical properties than neat PCL.

    Cellulose nanocrystal (CNC)-reinforced polyvinyl acetate (PVAc) nanocomposites were also investigated. CNC were modified via “SI-reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthate” (SI-RAFT/MADIX) polymerization of vinyl acetate (VAc). The resulting nanocomposites exhibited improved mechanical performance than the unmodified CNC.

    It is generally agreed that covalent grafting is superior to physical adsorption for the modification of a reinforcing agent. However, this hypothesis has never been thoroughly investigated. CNC was modified either through covalent grafting or through physical adsorption of poly(butyl methacrylate) (PBMA). Both methods resulted in improved mechanical performance than that of pure PCL or PCL containing unmodified CNC. However, covalent grafting gave the best mechanical performance even at high relative humidity.

    Functionalized CNC (F-CNC) were obtained through a versatile methodology employing organic acids bearing a functional group were employed for the simultaneous acid hydrolysis and esterification of cellulose fibers. This provided a facile route for the preparation of F-CNC.

  • 4.
    Boujemaoui, Assya
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ansari, Farhan
    Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nanostructural Effects in High Cellulose Content Thermoplastic Nanocomposites with a Covalently Grafted Cellulose-Poly(methyl methacrylate) Interface2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 598-607Article in journal (Refereed)
    Abstract [en]

    A critical aspect in materials design of polymer nanocomposites is the nature of the nanoparticle/polymer interface. The present study investigates the effect of manipulation of the interface between cellulose nanofibrils (CNF) and poly(methyl methacrylate) (PMMA) on the optical, thermal, and mechanical properties of the corresponding nanocomposites. The CNF/PMMA interface is altered with a minimum of changes in material composition so that interface effects can be analyzed. The hydroxyl-rich surface of CNF fibrils is exploited to modify the CNF surface via an epoxide-hydroxyl reaction. CNF/PMMA nanocomposites are then prepared with high CNF content (similar to 38 wt %) using an approach where a porous CNF mat is impregnated with monomer or polymer. The nanocomposite interface is controlled by either providing PMMA grafts from the modified CNF surface or by solvent-assisted diffusion of PMMA into a CNF network (native and modified). The high content of CNF fibrils of similar to 6 nm diameter leads to a strong interface and polymer matrix distribution effects. Moisture uptake and mechanical properties are measured at different relative humidity conditions. The nanocomposites with PMMA molecules grafted to cellulose exhibited much higher optical transparency, thermal stability, and hygro-mechanical properties than the control samples. The present modification and preparation strategies are versatile and may be used for cellulose nanocomposites of other compositions, architectures, properties, and functionalities.

  • 5.
    Boujemaoui, Assya
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlsson, Linn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lahcini, Mohammed
    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.
    Sehaqui, Houssine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Facile Preparation Route for Nanostructured Composites: Surface-Initiated Ring-Opening Polymerization of epsilon-Caprolactone from High-Surface-Area Nanopaper2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 6, p. 3191-3198Article in journal (Refereed)
    Abstract [en]

    In this work, highly porous nanopaper, i.e., sheets of papers made from non-aggregated nanofibrillated cellulose (NFC), have been surface-grafted with poly(epsilon-caprolactone) (PCL) by surface-initiated ring-opening polymerization (SI-ROP). The nanopaper has exceptionally high surface area (similar to 300 m(2)/g). The "grafting from" of the nanopapers was compared to "grafting from" of cellulose in the form of filter paper, and in both cases either titanium n-butoxide (Ti(On-Bu)(4)) or tin octoate (Sn(Oct)(2)) was utilized as a catalyst. It was found that a high surface area leads to significantly higher amount of grafted PCL in the substrates when Sn(Oct)2 was utilized as a catalyst. Up to 79 wt % PCL was successfully grafted onto the nanopapers as compared to filter paper where only 2-3 wt % PCL was grafted. However, utilizing Ti(On-Bu)4 this effect was not seen and the grafted amount was essentially similar, irrespectively of surface area. The mechanical properties of the grafted nanopaper proved to be superior to those of pure PCL films, especially at elevated temperatures. The present bottom-up preparation route of NFC-based composites allows high NFC content and provides excellent nanostructural control. This is an important advantage compared with some existing preparation routes where dispersion of the filler in the matrix is challenging.

  • 6.
    Boujemaoui, Assya
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Mazieres, Stephane
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Destarac, Mathias
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    SI-RAFT/MADIX polymerization of vinyl acetate on cellulose nanocrystals for nanocomposite applications2016In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 99, p. 240-249Article in journal (Refereed)
    Abstract [en]

    In the present work, poly(vinyl acetate) grafted cellulose nanocrystals (CNC-g-PVAc) were prepared via surface initiated reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthates (SI-RAFT/MADIX) polymerization. Successful grafting of PVAc from CNC was confirmed by FT-IR and TGA analysis. PVAc nanocomposites reinforced with CNC-g-PVAc, as well as pristine CNC for comparison, of different weight percentages (0.5, 1, 3 and 5 wt%) of CNC were prepared via solvent casting. The PVAc reinforced with CNC-g-PVAc resulted in higher transparency and improved mechanical properties compared with unmodified CNC nanocomposites. The addition of 5 wt% CNC-g-PVAc increased the modulus of neat PVAc with as much as 154%. The proposed SI-RAFT/MADIX on CNC could be applied to wide range of monomers, and it is believed to be an efficient and robust method for CNC functionalization, thus expanding the potential applicability of CNC.

  • 7.
    Boujemaoui, Assya
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mongkhontreerat, Surinthra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Preparation and characterization of functionalized cellulose nanocrystals2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, p. 457-464Article in journal (Refereed)
    Abstract [en]

    In this work, a series of functional nanocrystals (F-CNCs) was successfully produced by an efficient preparation method, combining acid hydrolysis and Fischer esterification with various organic acids. Functionalities such as ATRP initiators, double bonds, triple bonds, and thiols could be incorporated on CNCs. Surface modification was confirmed by FT-IR, XPS, and elemental analysis. Physical properties of FC-NCs were assessed by AFM, XRD and TGA. Moreover, ATRP initiator functionalized CNCs were utilized to graft poly(methyl methacrylate) via ATRP, thiol functionalized CNCs were reacted with Ellman's reagent to determine the thiol content and dye disperse red 13 was attached to alkyne functionalized CNCs to estimate the propiolate content. The herein presented method is a highly versatile and straightforward procedure for the preparation of F-CNCs which is believed to be a better alternative for the commonly utilized, extensive, multistep, and time consuming post functionalization methods.

  • 8.
    Carlmark, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Boujemaoui, Assya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mongkhontreerat, Surinthra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Functional cellulose nanocrystals for ATRP and click chemistry-preparation and characterization2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 9.
    Carlsson, Linn K.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sehaqui, Houssine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lachini, Mohammad
    Malmström Jonsson, Eva E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Carlmark, Anna E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Synthesis and characterization of biocomposites from cellulose nano- and filter papers prepared by ring-opening polymerization of epsilon-caprolactone with titanium based catalyst2012In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Article in journal (Other academic)
  • 10.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Hatton, Fiona
    Loughborough Univ, Dept Mat, Loughborough, Leics, England..
    Benselfelt, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Freire, Carmen
    Univ Aveiro, Aveiro Inst Mat, Aveiro, Portugal..
    Vilela, Carla
    Univ Aveiro, Aveiro Inst Mat, Aveiro, Portugal..
    Boujemaoui, Assya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Sanchez, Carmen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Lo Re, Giada
    Chalmers Univ Technol, Gothenburg, Sweden..
    Wågberg, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, Superseded Departments (pre-2005), Pulp and Paper Technology. KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden.;KTH Royal Inst Technol, Wallenberg Wood Sci Ctr, Stockholm, Sweden..
    D'Agosto, Franck
    UCBL, CPE Lyon, C2P2, CNRS,CPE, Bat 308F, Villeurbanne, France..
    Lansalot, Muriel
    UCBL, CPE Lyon, C2P2, CNRS,CPE, Bat 308F, Villeurbanne, France..
    Carlmark, Anna
    RISE, Stockholm, Sweden..
    Malmström, Eva
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Tailored PISA-latexes for modification of nanocellulosics: Investigating compatibilizing and plasticizing effects2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 11.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hatton, Fiona
    Univ Sheffield, Dept Chem, Sheffield, S Yorkshire, England..
    Boujemaoui, Assya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sanchez, Carmen Cobo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    D'Agosto, Franck
    C2P2 CNRS CPE UCBL, CPE Lyon, Bat 308F, Villeurbanne, France..
    Lansalot, Muriel
    C2P2 CNRS CPE UCBL, CPE Lyon, Bat 308F, Villeurbanne, France..
    Fogelstrom, Linda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Carlmark, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. RISE Res Inst Sweden Div Bioecon, Nanocellulose, Stockholm, Sweden..
    Tailored nano-latexes for modification of nanocelluloses: Compatibilizing and plasticizing effects2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 12.
    Kaldéus, Tahani
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. RISE Bioecon, Drottning Kristinas Väg 61, S-11486 Stockholm, Sweden..
    Boujemaoui, Assya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    One-pot preparation of bi-functional cellulose nanofibrils2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 12, p. 7031-7042Article in journal (Refereed)
    Abstract [en]

    Herein, we present a route to obtain bi-functional cellulose nanofibrils (CNF) by a one-pot approach using an already established functionalisation route, carboxymethylation, to which a subsequent functionalisation step, allylation or alkynation, has been added in the same reaction pot, eliminating the need of solvent exchange procedures. The total charge of the fibres and the total surface charge of the nanofibrils were determined by conductometric and polyelectrolyte titration, respectively. Furthermore, the allyl and alkyne functionalised cellulose were reacted with methyl 3-mercaptopropionate and azide-functionalised disperse red, respectively, to estimate the degree of functionalisation. The samples were further assessed by XPS and FT-IR. Physical characteristics were evaluated by CP/MAS C-13-NMR, XRD, AFM and DLS. This new approach of obtaining bi-functionalised CNF allows for a facile and rapid functionalisation of CNF where chemical handles can easily be attached and used for further modification of the fibrils.

  • 13.
    Larsson, Emma
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Thermoresponsive cryogels reinforced with cellulose nanocrystalsManuscript (preprint) (Other academic)
    Abstract [en]

    Herein, we report the first study of thermoresponsive cryogels with cellulose nanocrystals (CNCs) incorporated into the structure. Free radical polymerization was utilized to synthesize cryogels of poly(N-isopropylacrylamide) (PNIPAAm), resulting in thermoresponsive gels after the cryo-polymerization. Two types of CNCs were investigated: one which had reactive vinyl groups on the surface, enabling covalent incorporation and crosslinking with the cryogel network; and one which had no reactive groups on the surface, rendering it physically embedded in the network. The degree of crosslinking of the cryogels was controlled by varying the addition of N,N´-methylenebisacrylamide (MBAm). The cryogels were analyzed by FE-SEM and were all found to be macroporous. The morphology of the gels was largely dependent on the reaction conditions and the presence of CNC. The swelling properties of the freeze-dried gels were investigated and all gels exhibited a thermoresponsive behavior. Our study showed that the incorporation of CNCs is an effective method to alter both the morphologies and the mechanical properties of a cryogel, although the final properties of the cryogels depend on several different parameters. Due to the complexity of the system, a clear trend regarding the CNC incorporation is difficult to conclude, but compression testing showed that a cryogel having 1 wt% of crosslinkable CNC was far superior to the other gels in terms of mechanical properties, exhibiting that the presence of crosslinkable groups on the surface of CNCs could have a large influence over the final properties.

  • 14.
    Larsson, Emma
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Thermoresponsive cryogels reinforced with cellulose nanocrystals2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 95, p. 77643-77650Article in journal (Refereed)
    Abstract [en]

    Herein, we report the first study of thermoresponsive cryogels with cellulose nanocrystals (CNCs) incorporated into the structure. Free radical polymerization was utilized to synthesize cryogels of poly(N-isopropylacrylamide) (PNIPAAm), resulting in thermoresponsive gels after the cryo-polymerization. Two types of CNCs were investigated: one which had reactive vinyl groups on the surface, enabling covalent incorporation and crosslinking with the cryogel network; and one which had no reactive groups on the surface, rendering it physically embedded in the network. The degree of crosslinking of the cryogels was controlled by varying the addition of N,N'-methylenebisacrylamide (MBAm). The cryogels were analyzed by FE-SEM and were all found to be macroporous. The morphology of the gels was largely dependent on the reaction conditions and the presence of CNC. The swelling properties of the freeze-dried gels were investigated and all gels exhibited a thermoresponsive behavior. Our study showed that the incorporation of CNCs is an effective method to alter both the morphologies and the mechanical properties of a cryogel, although the final properties of the cryogels depend on several different parameters. Due to the complexity of the system, a clear trend regarding the CNC incorporation is difficult to conclude, but compression testing showed that a cryogel having 1 wt% of crosslinkable CNC was far superior to the other gels in terms of mechanical properties, exhibiting that the presence of crosslinkable groups on the surface of CNCs could have a large influence over the final properties.

  • 15.
    Lo Re, Giada
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Spinella, Stephen
    NYU Tandon School of Engineering, Six Metrotech Center, Brooklyn, New York 11201, United States.
    Boujemaoui, Assya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Vilaseca, Fabiola
    BIMATEC Group, Department of Chemical Engineering, Agricultural and Food Technology, University of Girona, C/Maria Aurèlia Capmany 61, 17003 Girona, Spain.
    Larsson, Per Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. RISE Bioeconomy, Teknikringen 56, Stockholm, SE-100 44, Sweden.
    Adås, Fredrik
    RISE Bioeconomy, Teknikringen 56, Stockholm, SE-100 44, Sweden.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance2018In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, no 6, p. 6753-6760Article in journal (Refereed)
    Abstract [en]

    Poly(epsilon-caprolactone) (PCL) is a ductile thermoplastic, which is biodegradable in the marine environment. Limitations include low strength, petroleum-based origin, and comparably high cost. Cellulose fiber reinforcement is therefore of interest although uniform fiber dispersion is a challenge. In this study, a one-step wet compounding is proposed to validate a sustainable and feasible method to improve the dispersion of the cellulose fibers in hydrophobic polymer matrix as PCL, which showed to be insensitive to the presence of the water during the processing. A comparison between unmodified and acetylated cellulosic wood fibers is made to further assess the net effect of the wet feeding and chemical modification on the biocomposites properties, and the influence of acetylation on fiber structure is reported (ATR-FTIR, XRD). Effects of processing on nano fibrillation, shortening, and dispersion of the cellulose fibers are assessed as well as on PCL molar mass. Mechanical testing, dynamic mechanical thermal analysis, FE-SEM, and X-ray tomography is used to characterize composites. With the addition of 20 wt % cellulosic fibers, the Young's modulus increased from 240 MPa (neat PCL) to 1850 MPa for the biocomposites produced by using the wet feeding strategy, compared to 690 MPa showed for the biocomposites produced using dry feeling. A wet feeding of acetylated cellulosic fibers allowed even a greater increase, with an additional 46% and 248% increase of the ultimate strength and Young's modulus, when compared to wet feeding of the unmodified pulp, respectively.

  • 16.
    Mongkhontreerat, Surinthra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Andrén, Oliver C. J.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Dendritic hydrogels: From exploring various crosslinking chemistries to introducing functions and naturally abundant resources2015In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 53, no 21, p. 2431-2439Article in journal (Refereed)
    Abstract [en]

    Dendritic hydrogels from dendritic-linear-dendritic (DLD) block copolymers based on PEG and bis-MPA dendrons were constructed via UV-initiated thiol-ene, thiol-yne, CuAAC, and amine-NHS crosslinking chemistries. Stoichiometric ratio manipulations, prior to film formation, resulted in functional hydrogels with tuneable compressive moduli. The highest gel fractions for all networks were obtained at off-stoichiometric ratios with surplus of DLDs. Finally, sustainable networks were fabricated by amalgamating DLD, naturally abundant cellulose nanocrystal, and protein-based bovine serum albumin.

  • 17. Willgert, Markus
    et al.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Constable, Edwin C.
    Housecroft, Catherine E.
    Copper-based dye-sensitized solar cells with quasi-solid nano cellulose composite electrolytes2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 61, p. 56571-56579Article in journal (Refereed)
    Abstract [en]

    The study presented describes the preparation of solvent-free nano composite gel electrolytes in combination with copper(I)-based dye-sensitized solar cells (DSSCs). The electrolytes comprise poly(ethylene oxide) (PEO) and cellulose nano crystals (CNCs) and an I-3(-)/I- redox shuttle. The quasi-solid-state DSSCs show increased photoconversion performance with increased amount of CNC in the electrolyte. DSSC performances measured on the day that the devices are fabricated show that when the electrolyte is composed of 80% CNC, a cell efficiency of 1.09% is reached compared to 1.16% using a standard liquid I-3(-)/I- electrolyte. DSSCs containing the nano composites and the copper(I)-based dye show robust stability over time, and after 60 days, DSSCs with the PEO/CNC/I-3(-)/I- electrolyte outperform those containing the liquid electrolyte.

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