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  • 551.
    Vilaseca, Fabiola
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Serra, Albert
    Univ Girona, Dept Chem Engn, Lab Paper Technol & Polymer Mat LEPAMAP, Girona 17003, Spain..
    Kochumalayil, Joby J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Xyloglucan coating for enhanced strength and toughness in wood fibre networks2020Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 229, artikel-id 115540Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent times, cellulosic materials are witnessing strong interest from both industry and academia for their ability to progress in high-value products with green stamp. Besides the renewability and biodegradability appeal, exceptional properties such as mechanical strength together with toughness are pursued. In the present work, wood fibre networks from eucalyptus Kraft pulp fibres and cellulose nanofibres are combined to produce nanostructured composite networks with outstanding mechanical behaviour. For this purpose, xyloglucan (XG) polymer is adsorbed on cellulose nanofibres (CNF) forming core-shell CNF fibrils in hydrocolloidal suspension which is used to dramatically strengthen wood fibre networks. TEMPO-CNF at two different oxidation levels were coated with XG. The exceptional Young's modulus and tensile strength found for fibre networks with only 10 wt% CNF was attributed to the fibre-fibre bond strength with better homogeneous stress distribution at the micro/nano scale. The production, mechanical characterization and structure analysis of such bionanocomposites is here presented.

  • 552.
    Vilela, Carla
    et al.
    Department of Chemistry, CICECO – Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-193, Portugal.
    Engström, Joakim
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Valente, Bruno F. A.
    Department of Chemistry, CICECO – Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-193, Portugal.
    Jawerth, Marcus
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Carlmark, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Freire, Carmen S. R.
    Department of Chemistry, CICECO – Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-193, Portugal.
    Exploiting poly(ɛ-caprolactone) and cellulose nanofibrils modified with latex nanoparticles for the development of biodegradable nanocomposites2018Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study reports the development of nanocomposites based on poly(?-caprolactone) (PCL) and cellulose nanofibrils (CNF) modified with cationic latex nanoparticles. The physical adsorption of these water-based latexes on the surface of CNF was studied as an environment-friendly strategy to enhance the compatibility of CNF with a hydrophobic polymeric matrix. The latexes are composed of amphiphilic block copolymers based on cationic poly(N,N-dimethylaminoethyl methacrylate-co-methacrylic acid) as the hydrophilic block, and either poly(methyl methacrylate) or poly(n-butyl methacrylate) as the hydrophobic block. The simple and practical melt-mixing of PCL- and latex-modified CNF yielded white homogeneous nanocomposites with complete embedment of the nanofibrils in the thermoplastic matrix. All nanocomposites are semicrystalline materials with good mechanical properties (Young's modulus?=?43.6?52.3 MPa) and thermal stability up to 335?340°C. Degradation tests clearly showed that the nanocomposites slowly degrade in the presence of lipase-type enzyme. These PCL/CNF-latex nanocomposite materials show great promise as future environmentally friendly packaging materials. POLYM. COMPOS., 2018. ? 2018 Society of Plastics Engineers

  • 553.
    Wahlström, Niklas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Polysaccharides from red and green seaweed: Extraction, characterisation and applications2020Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Algodling är en stor industri i Asien, men i stort sett outvecklad i Sverige. Algodling erbjuder många fördelar jämfört med odling av landbaserad biomassa. Algodlingar upptar inte värdefulla landområden och kräver ingen konstbevattning eller gödningsmedel vilket förebygger övergödning i kustnära miljöer. Alger är en potentiell råvara för framställning av biobränslen och biobaserade material. Syftet med detta avhandlingsarbete var att utveckla metoder för att extrahera och strukturbestämma polysackarider från makroalger som odlats på västkusten i Sverige. De extraherade polysackariderna användes sedan för att framställa några olika biobaserade material. I den första studien utvecklades en metod för att fraktionera proteiner och polysackarider från den röda makroalgen Porphyra. En proteinfraktion och tre polysackaridfraktioner erhölls vid fraktioneringen. I den andra studien utvecklades två olika protokoll för att extrahera polysackariden ulvan från två olika arter den gröna makroalgen Ulva. Extraktion med saltsyralösning gav ett högre utbyte av ulvan än extraktion med vatten. Sammansättningen av monosackarider hos det extraherade ulvanet varierade beroende på vilken extraktionsmetod som användes och även på vilken art av Ulva som användes. I den tredje studien tillverkades hydrogeler av ulvan som extraherats från Ulva. Ulvan oxiderades först till ulvan dialdehyd och blandades sedan med gelatin vilket ledde till bildningen av hydrogeler. Hydrogelerna visade en god svällningsförmåga i vatten och god förmåga att adsorbera färgämnet metylenblått. Hydrogelerna adsorberade också tungmetalljoner i viss utsträckning. I den fjärde studien extraherades cellulosa från Ulva och den extraherade cellulosan användes sedan vidare för att tillverka nanocellulosa (CNF) och regenererad cellulosa. Kemisk analys av nanocellulosan visade att den innehåller mest cellulosa, men även en mindre mängd av en xylos-glukossampolymer. Kristalliniteten uppmättes till 48% och det uppmätta XRD difraktogrammet indikerade förekomst av allomorfen cellulosa I.

    Publikationen är tillgänglig i fulltext från 2020-12-31 10:00
  • 554.
    Wahlström, Niklas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Edlund, Ulrica
    Pavia, Henrik
    Toth, Gunilla
    Jaworski, Aleksander
    Pell, Andrew J
    Choong, Ferdinand X
    Shirani, Hamid
    Nilsson, K. Peter R.
    Richter-Dahlfors, Agneta
    Cellulose from the green macroalgae ulva lactuca: isolation, characterization, optotracing, and production of cellulose nanofibrils2020Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated indoors under controlled conditions, followed by (2) its utilization in the production of lignin-free cellulose nanofibrils (CNF). Cellulose was extracted by sequential treatment with ethanol, hydrogen peroxide, sodium hydroxide, and hydrochloric acid, yielding a cellulose-rich insoluble fraction. The extracted cellulose was disintegrated into CNF using a mechanical homogenization process without any further enzymatic pre-treatments. In addition, regenerated cellulose was prepared. XRD characterization of the CNF showed characteristic peaks for the cellulose I allomorph and confirmed that the nanofibrils were semicrystalline with a crystallinity index of 48%. Regenerated cellulose was mostly amorphous with an XRD pattern indicating the presence of the cellulose II allomorph. The cellulose fractions were essentially free from inorganic substances and thermally stable up to around 260 degrees C. Structural mapping with CP-MAS C-13-NMR sustains the cellulose content of CNF and regenerated cellulose, respectively, yet ion chromatography identified the presence of 10-15% xylose in the fractions. Optotracing was used as a novel and non-disruptive tool to selectively assess the polysaccharide composition of the cellulose fractions and produced CNF aiming to shed light on this hitherto non-resolved origin of xylose in Ulva cell wall matter. Fluorescence excitation and emission spectra of a panel of 4 oligothiophenes identified and verified the presence of cellulose and sustain the conclusion that the isolated fractions consist of cellulose intertwined with a small amount of a xylose-containing glucan copolymer.

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  • 555.
    Wahlström, Niklas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Harrysson, H.
    Undeland, I.
    Edlund, Ulrica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    A Strategy for the Sequential Recovery of Biomacromolecules from Red Macroalgae Porphyra umbilicalis Kützing2018Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, nr 1, s. 42-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A nondestructive, multicomponent fractionation strategy has been developed to extract proteins and polysaccharides from the red macroalgae Porphyra umbilicalis collected along the west coast of Sweden and cultivated indoors under controlled conditions. First, a protein-rich fraction was extracted in an ice-cold alkaline solution. The overall protein content in Porphyra umbilicalis was estimated to be 30.6% of the dry weight, and out of that, 15.0% could be recovered. Water-soluble polysaccharides were then extracted from the insoluble residual fraction using sequential alkaline and acidic treatments at 90 °C for 4 h. Spectroscopic and chromatographic analyses of the polysaccharide fractions show that high-molecular-weight carrageenans were obtained from the alkaline extraction and a galactose-rich pectin substance was obtained from the acidic extraction. The insoluble fraction remaining after all extraction steps was rich in cellulose. An elemental analysis of Porphyra umbilicalis via scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS) showed the presence of C, O, Na, Ca, Mg, Al, Cl, and S. However, no heavy metals or other toxic elements, such as Pb, Hg, and As, were found.

  • 556.
    Wahlström, Niklas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Nylander, Filip
    Chalmers Univ Technol, Chem & Chem Engn Organ Chem, SE-41296 Gothenburg, Sweden..
    Malmhall-Bah, Eric
    Chalmers Univ Technol, Biol & Biol Engn Ind Biotechnol, SE-41296 Gothenburg, Sweden..
    Sjovold, Karin
    Edlund, Ulrica
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    Westman, Gunnar
    Chalmers Univ Technol, Chem & Chem Engn Organ Chem, SE-41296 Gothenburg, Sweden..
    Albers, Eva
    Chalmers Univ Technol, Biol & Biol Engn Ind Biotechnol, SE-41296 Gothenburg, Sweden..
    Composition and structure of cell wall ulvans recovered from Ulva spp. along the Swedish west coast2020Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 233, artikel-id 115852Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cell wall polysaccharide ulvan was isolated from two species of the seaweed Ulva collected along the Swedish west coast. Acidic extraction was benchmarked against hot water extraction with enzymatic purification and against commercial ulvan. Extracted ulvan contained 11-18 % g/g of ash, some protein (up to 1.3 % g N/g) but minimal colored impurities. The ulvans had high molecular weights (660,000-760,000 g/mol) and were composed of 77-79 % g/g carbohydrates, mainly rhamnose, xylose, glucose, glucuronic acid, and iduronic acid. The extraction protocol and the ulvan source strongly impact the molecular weight and the chemical composition. Acidic extraction caused almost complete desulfation of the isolated ulvan while the other method preserved a significant degree of SO3 substituents. Elemental analysis of ash remaining after thermal degradation showed presence of common mineral elements such as Na, Ca, Mg, Al, and K, but none of the heavy metals Pb, Hg, or As.

  • 557.
    Wahlström, Niklas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Steinhagen, Sophie
    Toth, Gunilla
    Pavia, Henrik
    Edlund, Ulrica
    Ulvan dialdehyde-gelatin hydrogels for removal of heavy metals and methylene blue from aqueous solutionManuskript (preprint) (Övrigt vetenskapligt)
  • 558. Wang, K.
    et al.
    Körstgens, V.
    Yang, D.
    Hohn, N.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
    Müller-Buschbaum, P.
    Morphology control of low temperature fabricated ZnO nanostructures for transparent active layers in all solid-state dye-sensitized solar cells2018Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 10, s. 4405-4415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on a method using sol-gel chemistry combined with diblock copolymer templating, a low-temperature route to fabricate zinc oxide (ZnO) films with tunable morphologies including foam-like, worm-like and sphere-like structures is demonstrated. The morphologies are probed using scanning electron microscopy and grazing-incidence small-angle X-ray scattering. Based on controlled nanostructured ZnO films, all solid-state dye-sensitized solar cells (ssDSSCs) are prepared, for which every layer is deposited at low temperature to reduce the energy consumption of the manufacturing process. Transparent active layers for ssDSSCs are obtained, which demonstrates the possibility for building integrated solar cells. The ssDSSCs with a worm-like ZnO morphology, exhibiting relatively better ordered interconnected three-dimensional structures and larger meso-pore sizes, show the highest power conversion efficiencies and almost 100% efficiency of charge separation and collection for the absorbed photons. After 120 days, almost 80% of the initial power conversion efficiency is maintained in ambient air conditions, which demonstrates good long-term stability of the ssDSSCs even without special encapsulation. 

  • 559.
    Wang, Kun
    et al.
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Biessmann, Lorenz
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrontron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsch Elektronen Synchrontron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Tuning of the Morphology and Optoelectronic Properties of ZnO/P3HT/P3HT-b-PEO Hybrid Films via Spray Deposition Method2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 24, s. 20569-20577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The self-assembly of amphiphilic diblock copolymers yields the possibility of using them as a template for tailoring the film morphologies of solgel chemistry-derived inorganic electron transport materials, such as mesoporous ZnO and TiO2. However, additional steps including etching and backfilling are required for the common bulk heterojunction fabrication process when using insulating diblock copolymers. Here, we use the conducting diblock copolymer poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) in which P3HT acts as charge carrier transport material and light absorber, whereas PEO serves as a template for ZnO synthesis. The initial solution is subsequently spray-coated to obtain the hybrid film. Scanning electron microscopy and grazing-incidence small-angle X-ray scattering measurements reveal a significant change in the morphology of the hybrid films during deposition. Optoelectronic properties illustrate the improved charge separation and charge transfer process. Both the amount of the diblock copolymer and the annealing temperature play an important role in tuning the morphology and the optoelectronic properties. Hybrid films being sprayed from a solution with the ratio of omega(ZnO), omega(P3HT), and omega(P3HT-b-PEO) of 2:1:1 and subsequent annealing at 80 degrees C show the most promising morphology combined with an optimal photoluminescence quenching. Thus, the presented simple, reagent- and energy-saving fabrication method provides a promising approach for a large-scale preparation of bulk heterojunction P3HT/ZnO films on flexible substrates.

  • 560.
    Wang, Kun
    et al.
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany. .
    Xia, Senlin
    Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
    Cao, Wei
    Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
    Hohn, Nuri
    Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
    Grott, Sebastian
    Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
    Kreuzer, Lucas P.
    Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany.
    Schwartzkopf, Matthias
    Deutsches Elektronen-Synchrontron (DESY), Notkestrasse 85, 22603 Hamburg, Germany.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsch Elektronen Synchrontron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany.
    Comparison of UV Irradiation and Sintering on Mesoporous Spongelike ZnO lms Prepared from PS-b-P4VP Templated Sol-Gel Synthesis2018Ingår i: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, nr 12, s. 7139-7148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous ZnO films with large surface-area-to-volume ratio show great omise in multiple applications, among which solid-state dye-sensitized lar cells (ssDSSCs) have attracted great attention in the field of otovoltaics. An appropriate mesopore size in the nanostructured ZnO lms significantly plays an indispensable role in improving the device ficiency that resulted from an efficient penetration of dye molecules d solid hole transport material. In the present work, mesoporous ongelike ZnO films are prepared using sol-gel synthesis templated by a block copolymer polystyrene-block-poly(4-vinylpyridine). Two different mplate removal techniques, ultraviolet (UV) irradiation and gh-temperature sintering, are used to compare their respective impact the pore sizes of the final ZnO thin films. Both the surface rphology and the inner morphology show that mesopores obtained via UV radiation are smaller as compared to their sintered counterparts. reover, increasing the template-to-ZnO precursor ratio is found to rther enlarge present mesopores. Accordingly, a strong correlation tween the pore sizes of sol-gel synthesized ZnO films and photovoltaic rformance of fabricated ssDSSCs is demonstrated. In contrast with the vices fabricated from the UV-irradiated ZnO films, those obtained from ntered samples show >2 times higher efficiency.

  • 561.
    Wang, Linqin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Sheibani, Esmaeil
    Guo, Yu
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Zhang, Wei
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Liu, Peng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Xu, Bo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Kloo, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Dalian Univ Technol, State Key Lab Fine Chem, Inst Artificial Photosynth, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China.
    Impact of Linking Topology on the Properties of Carbazole-Based Hole-Transport Materials and their Application in Solid-State Mesoscopic Solar Cells2019Ingår i: SOLAR RRL, ISSN 2367-198X, Vol. 3, nr 9, artikel-id 1900196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbazole is a promising core for the molecular design of hole-transport materials (HTMs) for solid-state mesoscopic solar cells (ssMSCs), such as solid-state dye-sensitized solar cells (ssDSSCs) and perovskite solar cells (PSCs) due to its low cost and excellent optoelectronic properties of its derivatives. Although carbazole-based HTMs are intensely investigated in ssMSCs and promising device performance is demonstrated, the fundamental understanding of the impact of linking topology on the properties of carbazole-based HTMs is lacking. Herein, the effect of the linking topology on the optical and electronic properties of a series of carbazole-based HTMs with 2,7-substitution and 3,6-substitution is systematically investigated. The results demonstrate that the 2,7-substituted carbazole-based HTMs display higher hole mobility and conductivity among this series of analogous molecules, thereby exhibiting better device performance. In addition, the conductivity of the HTMs is improved after light treatment, which explains the commonly observed light-soaking phenomenon of ssMSCs in general. All these carbazole-based HTMs are successfully applied in ssMSCs and one of the HTMs X50-based devices yield a promising efficiency of 6.8% and 19.2% in ssDSSCs and PSCs, respectively. This study provides guidance for the molecular design of effective carbazole-based HTMs for high-performance ssMSCs and related electronic devices.

  • 562.
    Wang, Linqin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Zhang, Jinbao
    Monash Univ, Dept Mat Sci & Engn, 22 Alliance Lane, Clayton, Vic 3800, Australia..
    Liu, Peng
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Xu, Bo
    Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, S-75120 Uppsala, Sweden..
    Zhang, Biaobiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Chen, Hong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Inge, A. Ken
    Stockholm Univ, Dept Mat & Environm Chem MMK, SE-10691 Stockholm, Sweden..
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wang, Haoxin
    Dalian Univ Technol, Inst Artificial Photosynth, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cheng, Yi-Bing
    Monash Univ, Dept Mat Sci & Engn, 22 Alliance Lane, Clayton, Vic 3800, Australia..
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Dalian Univ Technol, Inst Artificial Photosynth, DUT, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells2018Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, nr 69Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs.

  • 563. Wang, M.
    et al.
    Olszewska, A.
    Walther, A.
    Malho, J. -M
    Schacher, F. H.
    Ruokolainen, J.
    Ankerfors, M.
    Laine, J.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Österberg, M.
    Ikkala, O.
    Colloidal inonic self-assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites2013Ingår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2013, s. 6558-6567Konferensbidrag (Refereegranskat)
  • 564.
    Wang, M.
    et al.
    School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China.
    Zhao, Yadong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Li, Jiebing
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    From hollow lignin microsphere preparation to simultaneous preparation of urea encapsulation for controlled release using industrial kraft lignin via slow and exhaustive acetone-water evaporation2020Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 4, nr 1, s. 77-87Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignin nano/microparticles have recently attracted growing interest for various value-additive applications of lignin, especially encapsulation. In this study, in order to establish a highly efficient and highly productive preparation process to effectively utilize technical lignin, a brand-new, slow and exhaustive solution evaporation process following a simple, self-assembly principle was developed using industrial softwood kraft lignin (SKL) from a starting acetone-water (80/20, v/v) solution to recover 100% of the lignin as homogeneous and well-shaped microspheres. The prepared microspheres had a typical average diameter of 0.81 ± 0.15 μm and were hollow with very thin shells (of nanoscale thickness). Based on this developed technique, encapsulation of urea by these lignin microspheres was directly achieved using the same process as hollow lignin microspheres with urea attached to the outside and entrapped inside of the wall. Two distinct urea release rates were observed for the urea-encapsulated microspheres: a fast release of the urea outside the shell wall and a slow (controlled) release of the urea inside the shell wall. The encapsulation efficiency was as high as 46% of the trapped urea as encapsulated inside the lignin microspheres. The slow and exhaustive solution evaporation procedure reported here is a simple and straightforward method for the valorization of industrial kraft lignin as hollow microspheres with controllable, homogeneous and desired morphologies, and especially for the direct preparation of lignin-based encapsulating fertilizers for controlled release.

  • 565. Wang, W.
    et al.
    Widmann, T.
    Song, L.
    Fröschl, T.
    Hüsing, N.
    Mo, G.
    Wu, Z.
    Zhang, P.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fan, H.
    Müller-Buschbaum, P.
    Aging of low-temperature derived highly flexible nanostructured TiO 2 /P3HT hybrid films during bending2019Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 17, s. 10805-10814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To meet the demand for low-cost, lightweight, portable and building-integrated solar cells, developing flexible and cost-efficient photo-active hybrid films is of significant interest. In this work, we investigate the mechanical properties of hybrid layers consisting of mesoporous TiO 2 filled with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a function of the number of bending cycles. The TiO 2 /P3HT layers are deposited on flexible PET substrates at low temperatures (≤140 °C), which is beneficial for reducing the processing energy input and in turn lowering the production costs. Non-filled and partially filled mesoporous titania films are studied for comparison. The surface morphology is examined with scanning electron microscopy (SEM) before and after the bending tests. The inner film morphology is characterized with grazing incidence small-angle X-ray scattering (GISAXS). Based on the observed morphology, micromechanical models are used to analyze the mechanical properties of the investigated films. The results show that the TiO 2 /P3HT layers have a low elastic modulus and P3HT helps to stabilize the titania nanostructures against fracture. The SEM observations are well explained with the established models in a quantitative way.

  • 566.
    Wang, Zhen
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Malti, Abdellah
    KTH.
    Ouyang, Liangqi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Tu, D.
    Tian, Weiqian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hamedi, Mahiar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Copper-Plated Paper for High-Performance Lithium-Ion Batteries2018Ingår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, nr 48, artikel-id 1803313Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Paper is emerging as a promising flexible, high surface-area substrate for various new applications such as printed electronics, energy storage, and paper-based diagnostics. Many applications, however, require paper that reaches metallic conductivity levels, ideally at low cost. Here, an aqueous electroless copper-plating method is presented, which forms a conducting thin film of fused copper nanoparticles on the surface of the cellulose fibers. This paper can be used as a current collector for anodes of lithium-ion batteries. Owing to the porous structure and the large surface area of cellulose fibers, the copper-plated paper-based half-cell of the lithium-ion battery exhibits excellent rate performance and cycling stability, and even outperforms commercially available planar copper foil-based anode at ultra-high charge/discharge rates of 100 C and 200 C. This mechanically robust metallic-paper composite has promising applications as the current collector for light-weight, flexible, and foldable paper-based 3D Li-ion battery anodes.

  • 567.
    Wang, Zhen
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Ouyang, Liangqi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Tian, Weiqian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Marais, Andrew
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Tybrandt, Klas
    Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, S-60174 Norrkoping, Sweden.;Linkoping Univ, Dept Sci & Technol, Lab Organ Elect, Wallenberg Wood Sci Ctr, S-60174 Norrkoping, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hamedi, Mahiar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Layer-by-Layer Assembly of High-Performance Electroactive Composites Using a Multiple Charged Small Molecule2019Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 35, nr 32, s. 10367-10373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Layer-by-layer (LbL) assembly is a versatile tool for fabricating multilayers with tailorable nanostructures. LbL, however, generally relies on polyelectrolytes, which are mostly insulating and induce large interlayer distances. We demonstrate a method in which we replace polyelectrolytes with the smallest unit capable of LbL self-assembly: a molecule with multiple positive charges, tris(3-aminopropyl)amine (TAPA), to fabricate LbL films with negatively charged single-walled carbon nanotubes (CNTs). TAPA introduces less defects during the LbL build-up and results in more efficient assembly of films with denser micromorphology. Twenty bilayers of TAPA/CNT showed a low sheet resistance of 11 k Omega, a high transparency of 91% at 500 nm, and a high electronic conductivity of 1100 S/m on planar substrates. We also fabricated LbL films on porous foams with a conductivity of 69 mS/m and used them as electrodes for supercapacitors with a high specific capacitance of 43 F/g at a discharging current density of 1 A/g.

  • 568.
    Wei, Xin-Feng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ageing behavior of plastics used in automotive fuel systems2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    En ökning i servicetemperatur och användning av biobaserade drivmedel, t.ex. biodiesel, har väckt frågeställningar om hur detta påverkar egenskaperna på kort och lång sikt hos plastkomponenter som används i fordonsbränslesystem.

    I detta arbete har egenskaperna undersökts hos oförstärkt och glasfiberarmerad polyamid 12 (PA12), utsatt för tre olika bränslen (petroleumdiesel, biodiesel och en blandning av dessa (80/20)) vid hög temperatur. Interaktionen mellan polymeren och bränslet och tillhörande åldringsmekanismer hos polymeren (bränsleupptag, extraktion av monomer och oligomer, anlöpning och oxidation) befanns vara "generiska" i den mening att de inträffade, dock i olika grad, för alla bränslen. För glasfiberarmerad polyamid skedde åldrandet huvudsakligen i polyamid-matrisen och inte i gränsskiktet mellan matris och fiber. Semi-aromatisk polyamid visade bättre prestanda än alifatisk PA12 när dessa utsattes för bränslena.

    På komponentnivå åldrades flerskikts-polyamid-baserade rör, med polyamid eller fluorpolymer som inre skikt, under ”fordons-lika förhållanden” med bränsle på insidan och luft på utsidan. Alla rör förstyvades under åldrandet men en försprödning inträffade endast för rören med polyamid som inre skikt. Jämfört med polyamiden uppvisade det inre skiktet av fluorpolymer betydligt bättre barriäregenskaper gentemot bränslet och inget material extraherades ut i bränslefasen. Mjukgöraravgången från ytterskikten av PA12 i kontakt med luft var diffusionsstyrd och följde ett linjärt Arrhenius-beteende i högtemperatur-området. Sambanden mellan mjukgöraravgång och förändringar i de mekaniska egenskaperna fastställdes.

    Polyamiderna genomgick diffusionsbegränsad oxidation när de utsattes för luft och/eller bränsle, vilket resulterade i bildandet av ett tunt oxiderat ytskikt, vilket i sig bidrog till en avsevärd sänkning i brottöjning.

    Brott-beteendet hos PA6 i luft vid hög temperatur studerades systematiskt, vilket ledde till att underliggande mekanismer som var ansvariga för minskningen av brottöjningen i tre distinkta stadier, kunde tas fram.

     

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  • 569.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    De Vico, Loris
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larroche, Pierre
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kallio, Kai
    Bruder, Stefan
    Bellander, Martin
    Gedde, Ulf W.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Ageing properties and polymer/fuel interactions of polyamide 12 exposed to (bio)diesel at high temperature2019Ingår i: npj Materials Degradation, ISSN 2397-2106, nr 3, artikel-id 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biodiesel derived from oil crops and animal fats has been developed as a promising carbon-neutral alternative to petroleum fuels in the transport sector, but the compatibility between biodiesel/petroleum diesel and polymer components in the automotive fuel system has not been free from controversy. In this present study, the degradation of polyamide 12 (PA12), one of the most common polymers used in vehicle fuel systems, has been investigated after exposure to petroleum diesel, biodiesel and a mixture of these (20 vol.% of biodiesel/80 vol.% petroleum diesel). Fuel sorption kinetics, glass transition temperature data and mechanical properties all showed that the fuels plasticized the PA12. In addition, monomers and oligomers were extracted from PA12 by the fuels. The long-term exposure led to oxidation and an annealing-induced increase in crystallinity of the polymer. The plasticization, oxidation and annealing effects were combined with the tensile mechanical properties to assess the overall degree of ageing and degradation of the PA12 material. The fuel-polymer interactions and ageing mechanisms, demonstrated here at high temperature for PA12, are 'generic' in the sense that they are also expected to occur, to various degrees, with many other polymers and they indicate that care should be taken when choosing polymers in applications where they will be exposed to fuels at high temperature.

  • 570.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Degradation of polyamide 12 exposed to petroleum diesel, biodiesel and their mixture2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Artikel i tidskrift (Övrigt vetenskapligt)
  • 571.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kallio, K. J.
    Bruder, S.
    Bellander, M.
    Gedde, Ulf W
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Long-term performance of a polyamide-12-based fuel line with a thin poly(ethylene-co-tetrafluoroethylene) (ETFE) inner layer exposed to bio- and petroleum diesel2018Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 156, s. 170-179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The long-term performance of a polyamide-12 (PA12)-based (bio)diesel fuel line/pipe with a thin poly(ethylene-co-tetrafluoroethylene) (ETFE) inner layer was investigated in “close to real” and high-temperature isothermal conditions with fuel on the inside and air on the outside of the pipe. The inner carbon-black-containing ETFE layer resisted fuel attack, as revealed by the small fuel uptake, the very low degree of oxidation, and the unchanged electrical conductivity, glass transition and melting behaviour. The properties of the ETFE layer remained the same after exposure to all the fuel types tested (petroleum diesel, biodiesel and a blend of 80% diesel with 20% biodiesel). Because of the presence of the ETFE layer on the inside, the fuel pipe experienced noticeable changes only in the outer PA12 pipe layer through migration of plasticizer, annealing and slight oxidation. The evaporation of plasticizer was found to be diffusion-controlled and it led to an increase in the glass transition temperature of PA12 by 20 °C. This, together with a small annealing-induced increase in crystallinity, resulted in a stiffer and stronger pipe with an increase in the flexural/tensile modulus and strength. The oxidation of PA12 remained at a low level and did not lead to an embrittled pipe during the simulated lifetime of the vehicle. This study reveals that fluoropolymers have a great potential for use as fuel-contacting materials in “demanding” motor vehicle fuel line systems. 

  • 572.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kallio, Kai
    Bruder, Stefan
    Bellander, Martin
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Plasticizer loss in a complex system (polyamide 12): Kinetics, prediction and its effects on mechanical properties2019Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 169, nr 108985Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasticizer migration is a major concern for plasticized polymers because it leads to unwanted changes in mechanical properties and, in many cases, contamination of the environment. In cases of slow migration, it is of practical importance to be able to perform accelerated testing and estimate migration rates from high temperature experiments. Despite the importance, a critical evaluation of different ways of extrapolating mass loss data has hitherto not been reported. Therefore, in this article, three different methods (involving for the first time a master-curve approach to mass loss data) to estimate low temperature migration from high temperature data are presented and critically evaluated. The system chosen was a plasticized polyamide 12 pipe, an important component in vehicle fuel-line systems. This system was challenging since the lower part of the temperature range in which the material is used overlaps with the glass transition region. All three methods (using data at 80–145 °C) over-estimated, although to different extents, the low-temperature mass loss rate (60 °C). The main reason for the over-estimation was the partial overlap with the glass transition region. Hence, there is a built-in safety factor when predicting plasticizer loss over glass transition regions, and the predictions are conservative. It was observed that plasticizer loss and annealing effects were the main reasons for changes in mechanical properties (increase in flexural stiffness/strength) during ageing.

  • 573.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kallio, Kai
    Bruder, Stefan
    Bellander, Martin
    Olsson, Richard
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    High-performance glass-fibre reinforced biobased aromatic polyamide in automotive biofuel supply systemsManuskript (preprint) (Övrigt vetenskapligt)
  • 574.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kallio, Kai J.
    Volvo Car Corp, Polymer Ctr, SE-40531 Gothenburg, Sweden..
    Bruder, Stefan
    Scania CV AB, Mat Technol, SE-15187 Sodertalje, Sweden..
    Bellander, Martin
    Scania CV AB, Mat Technol, SE-15187 Sodertalje, Sweden..
    Kausch, Hans-Henning
    Swiss Fed Inst Technol Lausanne EPFL, CH-1015 Lausanne, Switzerland..
    Gedde, Ulf W
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Diffusion-limited oxidation of polyamide: Three stages of fracture behavior2018Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 154, s. 73-83Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyamides (PAs) frequently experience diffusion-limited oxidation (DLO) under elevated temperatures due to their combination of relatively high oxygen barrier properties and high susceptibility to, and rate of, oxidation; under DLO conditions, oxidation is uneven and limited to a thin surface layer. In this study, the reduced extensibility/embrittlement of unstabilized PA6 under DLO conditions was understood by revealing DLO-induced fracture behavior. The DLO was induced by thermally ageing PA6 samples at 180 degrees C; the built-up of the thin oxidized layer by ageing was revealed by infrared microscopy. Notably, the formation of the thin oxidized layer significantly reduced the strain-at-break. Depending on whether the oxidized layer was brittle, two types of surface behavior (voiding and cracking) occurred during the tensile tests, which in turn lead to three types (stages) of tensile fracture behavior. In particular, in the early stage (Stage I) of ageing, the fracture was caused by a long crack formed by the coalescence of adjacent surface voids, leading to a decrease in the strain-at-break from 300% to 30%. In Stage II, multiple surface cracks, which initiated in the oxidized layer, was arrested by the interface between the oxidized and unoxidized material, leading to an almost constant strain-at-break (at or close to the necking strain). Maximum brittleness occurred in Stage III, where a more extensive oxidation of the oxidized layer initiated cracks with high propagation rate, causing the interface to be unable to arrest the cracks. 

  • 575.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Linde, Erik
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Plasticiser loss from plastic or rubber products through diffusion and evaporation2019Ingår i: npj Materials Degradation, E-ISSN 2397-2106, artikel-id 18Artikel i tidskrift (Refereegranskat)
  • 576.
    Werner, Oskar
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Pettersson, Bert
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Characterisation of wetting by solidification of agarose solution sessile drops2009Ingår i: Superhydrophobic Surfaces, CRC Press , 2009, s. 475-486Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    A new method for characterising the wetting of structured surfaces is presented. Sessile drops of a warm agarose solution were placed on test surfaces and then removed after the gelation of the agarose solution caused by the cooling of the drop. By studying the base of the sessile drops using confocal microscopy and image processing it was possible to determine the wetting mode and general appearance of the liquid-gas interface beneath the drop. The method also shows potential to measure the wetted area, and local contact angles beneath the footprint of a sessile drop. The applicability of the method was also demonstrated by its application to periodically structured photopolymer plates and surfaces covered by microsized glass spheres. 

  • 577.
    Werner, Oskar
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Quan, Can
    Uppsala Univ, Dept Phys & Analyt Chem, NRCCRM, SE-75124 Uppsala, Sweden..
    Turner, Charlotta
    Wågberg, Lars
    KTH.
    CELL 204-Methods to render paper superhydrophobic2008Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 235Artikel i tidskrift (Övrigt vetenskapligt)
  • 578.
    Westlund, Robert
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Glimsdal, Eirik
    Norwegian Univ Sci & Technol, Dept Phys, N-7491 Trondheim, Norway..
    Lindgren, Mikael
    Norwegian Univ Sci & Technol, Dept Phys, N-7491 Trondheim, Norway..
    Lopes, Cesar
    Swedish Def Res Agcy, Dept Optron Syst, SE-58111 Linkoping, Sweden..
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    POLY 621-Click chemistry and dendrimer synthesis as tools for designing efficient optical power limiting platinum(II) acetylides2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Artikel i tidskrift (Övrigt vetenskapligt)
  • 579.
    Wienhold, Kerstin S.
    et al.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Koerstgens, Volker
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Grott, Sebastian
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Jiang, Xinyu
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany.;Heinz Maier Leibnitz Zentrum, Lichtenbergstr 1, D-85748 Garching, Germany..
    Effect of Solvent Additives on the Morphology and Device Performance of Printed Nonfullerene Acceptor Based Organic Solar Cells2019Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 45, s. 42313-42321Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Printing of active layers of high-efficiency organic solar cells and morphology control by processing with varying solvent additive concentrations are important to realize real-world use of bulk-heterojunction photovoltaics as it enables both up-scaling and optimization of the device performance. In this work, active layers of the conjugated polymer with benzodithio-phene units PBDB-T-SF and the nonfullerene small molecule acceptor IT-4F are printed using meniscus guided slot-die coating. 1,8-Diiodooctane (DIO) is added to optimize the power conversion efficiency (PCE). The effect on the inner nanostructure and surface morphology of the material is studied for different solvent additive concentrations with grazing incidence small-angle X-ray scattering (GISAXS), grazing incidence wide-angle X-ray scattering (GIWAXS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Optical properties are studied with photoluminescence (PL), UV/vis absorption spectroscopy, and external quantum efficiency (EQE) measurements and correlated to the corresponding PCEs. The addition of 0.25 vol % DIO enhances the average PCE from 3.5 to 7.9%, whereas at higher concentrations the positive effect is less pronounced. A solar cell performance of 8.95% is obtained for the best printed device processed with an optimum solvent additive concentration. Thus, with the large-scale preparation method printing similarly well working solar cells can be realized as with the spin-coating method.

  • 580.
    Wistrand, Anna
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Fuoco, Tiziana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Ahlinder, Astrid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Designing fiber-based, degradable 3D porous scaffolds suitable for soft tissue engineering2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 258Artikel i tidskrift (Övrigt vetenskapligt)
  • 581.
    Wu, Duo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Samanta, A.
    Srivastava, R. K.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Nano-graphene oxide functionalized bioactive poly(lactic acid) and poly(ε-caprolactone) nanofibrous scaffolds2018Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, nr 4, artikel-id 566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A versatile and convenient way to produce bioactive poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) electrospun nanofibrous scaffolds is described. PLA and PCL are extensively used as biocompatible scaffold materials for tissue engineering. Here, biobased nano graphene oxide dots (nGO) are incorporated in PLA or PCL electrospun scaffolds during the electrospinning process aiming to enhance the mechanical properties and endorse osteo-bioactivity. nGO was found to tightly attach to the fibers through secondary interactions. It also improved the electrospinnability and fiber quality. The prepared nanofibrous scaffolds exhibited enhanced mechanical properties, increased hydrophilicity, good cytocompatibility and osteo-bioactivity. Therefore, immense potential for bone tissue engineering applications is anticipated.

  • 582.
    Wu, Qiong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Jungstedt, Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Soltésova, Maria
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Mushi, Ngesa Ezekiel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    High strength nanostructured films based on well-preserved beta-chitin nanofibrils2019Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 22, s. 11001-11011Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chitin nanofibrils (ChNF) are interesting high-value constituents for nanomaterials due to the enormous amount of waste from the seafood industry. So far, the reported ChNFs are substantially modified and chemically degraded (shortened) during extraction from the organisms. Here, highly individualized and long native-state ss-chitin nanofibrils from Illex argentinus squid pens are prepared. A mild treatment was developed to preserve the molar mass, aspect ratio, degree of acetylation and crystallite structure. The fibrils show a uniform diameter of 2-7 nm, very high aspect ratio (up to 750), high degree of acetylation (DA = 99%), and high molar mass (843 500 dalton). The powder X-ray diffraction analysis showed the preserved crystallite structure after protein removal. These " high quality" ChNFs were used to prepare nanostructured films via vacuum filtration from stable hydrocolloids. The effects of well-preserved " native" fibrils on morphology, and film properties (mechanical and optical), were studied and compared with earlier results based on coarser and shorter, chemically degraded chitin fibrils.

  • 583.
    Wu, Qiong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Mushi, Ngesa Ezekiel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    High-Strength Nanostructured Films Based on Well-Preserved alpha-Chitin Nanofibrils Disintegrated from Insect Cuticles2020Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, nr 2, s. 604-612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The alpha-chitin nanofibril is an alternative to nanocellulose as a building-block for strong films and other nanomaterials. The hypothesis of high film strength for films based on mildly treated insect cuticles was tested. Fibrils from the cuticle of Ruspolia differens (a long-horned bush cricket grasshopper locally known as senene) are disintegrated by a mild process, subsequently characterized by transmission electron microscopy, NMR, Fourier transform infrared spectroscopy, and XRD, and used to prepare strong and transparent films. A mild process (with 20% NaOH treatment for 2 weeks and at room temperature) was used to largely remove the strongly bound protein associated with chitin. The purpose was to reduce chitin degradation. The native structure of chitin was indeed well preserved and close to the native state, as is supported by data for degree of acetylation, molar mass, crystallinity, and crystallite dimensions. The diameter of the smallest chitin fibrils was as small as 3-7 nm (average 6 nm) with lengths larger than or around 1 mu m. A stable and well -dispersed colloidal chitin fibril suspension in water was achieved. A nanostructured chitin film prepared by filtration showed high optical transmittance (similar to 90%) and very high tensile strength (220 MPa). The high tensile strength was attributed to the well-preserved chitin structure, high intrinsic fibril strength, and high colloidal stability of the fibril suspension. Strong, transparent insect chitin films offer interesting alternatives to nanocellulose films because of different resource origins, surface chemistries, and potential antimicrobial properties.

  • 584.
    Wu, Qiong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Mushi, Ngesa Ezekiel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    High-Strength Nanostructured Films Based on Well-Preserved α-Chitin Nanofibrils Disintegrated from Insect Cuticles2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The α-chitin nanofibril is an alternative to nanocellulose as a building-block for strong films and other nanomaterials. The hypothesis of high film strength for films based on mildly treated insect cuticles was tested. Fibrils from the cuticle of Ruspolia differens (a long-horned bush cricket grasshopper locally known as senene) are disintegrated by a mild process, subsequently characterized by transmission electron microscopy, NMR, Fourier transform infrared spectroscopy, and XRD, and used to prepare strong and transparent films. A mild process (with 20% NaOH treatment for 2 weeks and at room temperature) was used to largely remove the strongly bound protein associated with chitin. The purpose was to reduce chitin degradation. The native structure of chitin was indeed well preserved and close to the native state, as is supported by data for degree of acetylation, molar mass, crystallinity, and crystallite dimensions. The diameter of the smallest chitin fibrils was as small as 3-7 nm (average 6 nm) with lengths larger than or around 1 μm. A stable and well-dispersed colloidal chitin fibril suspension in water was achieved. A nanostructured chitin film prepared by filtration showed high optical transmittance (∼90%) and very high tensile strength (220 MPa). The high tensile strength was attributed to the well-preserved chitin structure, high intrinsic fibril strength, and high colloidal stability of the fibril suspension. Strong, transparent insect chitin films offer interesting alternatives to nanocellulose films because of different resource origins, surface chemistries, and potential antimicrobial properties.

  • 585.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Preparation, characterization and utilization of low density networks from cellulose nanofibrils2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Artikel i tidskrift (Övrigt vetenskapligt)
  • 586.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Use of model cellulose substrates to determine molecular interactions2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 587.
    Wågberg, Lars
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Granberg, Hjalmar
    RISE Bioecon, Stockholm, Sweden..
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Francon, Hugo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Zou, Fangxin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Östmans, Rebecca
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Spreading of water in low density nanocellulose networks: From capillaries to specific surface area2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 588.
    Wågberg, Lars
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hamedi, Max
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Marais, Andrew
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Stanford Univ, Stanford, CA 94305 USA..
    Nyström, Gustav
    Swiss Fed Inst Technol, Dept Hlth Sci & Technol, Zurich, Switzerland..
    Francon, Hugo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Granberg, Hjalmar
    RISE Bioecon, Stockholm, Sweden..
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Fibre & Polymer Technol, Stockholm, Sweden..
    The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for preparing new materials for energy storage2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 589.
    Xia, Senlin
    et al.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funktionelle Mat, Garching, Germany..
    Song, Lin
    Tech Univ Munich, Phys Dept, Lehrstuhl Funktionelle Mat, Garching, Germany.;Northwestern Polytech Univ, Inst Flexible Elect, West Youyi Rd 127, Xian 710072, Shaanxi, Peoples R China..
    Chen, Wei
    Tech Univ Munich, Phys Dept, Lehrstuhl Funktionelle Mat, Garching, Germany..
    Koerstgens, Volker
    Tech Univ Munich, Phys Dept, Lehrstuhl Funktionelle Mat, Garching, Germany..
    Opel, Matthias
    Bayer Akad Wissensch, Walther Meissner Inst, Walther Meissner Str 8, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funktionelle Mat, Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Printed Thin Diblock Copolymer Films with Dense Magnetic Nanostructure2019Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 24, s. 21935-21945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thin hybrid films with dense magnetic structures for sensor applications are printed using diblock copolymer (DBC) templating magnetic nanoparticles (MNPs). To achieve a high-density magnetic structure, the printing ink is prepared by mixing polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) with a large PS volume fraction and PS selective MNPs. Solvent vapor annealing is applied to generate a parallel cylindrical film morphology (with respect to the substrate), in which the MNP-residing PS domains are well separated by the PMMA matrix, and thus, the formation of large MNP agglomerates is avoided. Moreover, the morphologies of the printed thin films are determined as a function of the MNP concentration with real and reciprocal space characterization techniques. The PS domains are found to be saturated with MNPs at 1 wt %, at which the structural order of the hybrid films reaches a maximum within the studied range of MNP concentration. As a beneficial aspect, the MNP loading improves the morphological order of the thin DBC films. The dense magnetic structure endows the thin films with a faster superparamagnetic responsive behavior, as compared to thick films where identical MNPs are used, but dispersed inside the minority domains of the DBC.

  • 590.
    Xia, Senlin
    et al.
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Song, Lin
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Hohn, Nuri
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Wang, Kun
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Grott, Sebastian
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany..
    Opel, Matthias
    Bayer Akad Wissensch, Walther Meissner Inst, Walther Meissner Str 8, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Spray-Coating Magnetic Thin Hybrid Films of PS-b-PNIPAM and Magnetite Nanoparticles2019Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, nr 15, artikel-id 1808427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spray coating is employed to fabricate magnetic thin films composed of the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) and Fe3O4 magnetic nanoparticles (MNPs) functionalized with hydrophobic coatings. The kinetics of structure formation of the hybrid films is followed in situ with grazing incidence small angle X-ray scattering during the spray deposition. To gain a better understanding of the influence of MNPs on the overall structure formation, the pure polymer film is also deposited as a reference via an identical spray protocol. At the initial spraying stage, the hybrid film (containing 2 wt% of MNPs) exhibits a faster formation process of a complete film as compared to the reference. The existence of MNPs depresses the dewetting behavior of polymer films on the substrate at macroscale and simultaneously alters the polymer microphase separation structure orientation from parallel to vertical. As spraying proceeds, MNPs aggregate into agglomerates with increasing sizes. After the spray deposition is finished, both samples gradually reach an equilibrium state and magnetic films with stable structures are achieved in the end. Superconducting quantum interference device investigation reveals the superparamagnetic property of the sprayed hybrid film. Consequently, potential application of sprayed films in fields such as magnetic sensors or data storage appears highly promising.

  • 591.
    Xia, Senlin
    et al.
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Song, Lin
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Koerstgens, Volker
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Opel, Matthias
    Bayerische Akad Wissensch, Walther Meissner Inst, Walther Meissner Str 8, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Magnetic nanoparticle-containing soft-hard diblock copolymer films with high order2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 25, s. 11930-11941Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For sensor applications, superparamagnetic anisotropy is an indispensable property, which is typically achieved by employing an external field to guide the arrangement of magnetic nanoparticles (NPs). In the present investigation, the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAM) is printed as a template to localize magnetic iron oxide NPs without any external field. Via microphase separation, cylindrical nanostructures of PS in a PNIPAM matrix are obtained, aligned perpendicular to the substrate. Since the magnetite NPs (Fe3O4) are functionalized with hydrophobic organic chains showing affinity to the PS blocks, they can selectively aggregate inside the PS cylinders. Moreover, solvent vapor annealing allows the achievement of nanostructures inside the hybrid system with a very high order, even at a high NP loading. Therefore, NPs can accumulate within PS domains to form perpendicularly aligned aggregates with high periodicity. The magnetic properties of the hybrid films are determined at various temperatures in two orthogonal directions (with PS cylinders vertical and parallel to the applied magnetic field). All hybrid films show superparamagnetism and a remarkable magnetic anisotropy is achieved at certain NP concentrations. This investigation shows a facile route to prepare superparamagnetic films with magnetic anisotropy and offers a novel possibility to future magnetic sensor fabrication.

  • 592. Xu, Peng
    et al.
    Liu, Peng
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Xu, B.
    Kloo, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Hua, Y.
    D-A-D-Typed Hole Transport Materials for Efficient Perovskite Solar Cells: Tuning Photovoltaic Properties via the Acceptor Group2018Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 23, s. 19697-19703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two D-A-D-structured hole-transport materials (YN1 and YN2) have been synthesized and used in perovskite solar cells. The two HTMs have low-lying HOMO levels and impressive mobility. Perovskite-based solar cells (PSCs) fabricated with YN2 showed a power conversion efficiency (PCE) value of 19.27% in ambient air, which is significantly higher than that of Spiro-OMeTAD (17.80%). PSCs based on YN1 showed an inferior PCE of 16.03%. We found that the incorporation of the stronger electron-withdrawing group in the HTM YN2 improves the PCE of PSCs. Furthermore, the YN2-based PSCs exhibit good long-term stability retaining 91.3% of its initial efficiency, whereas PSCs based on Spiro-OMeTAD retained only 42.2% after 1000 h lifetime (dark conditions). These promising results can provide a new strategy for the design of D-A-D HTMs for PSC applications in future.

  • 593.
    Xu, X.
    et al.
    Chalmers Univ Technol, SE-41296 Gothenburg, Sweden..
    Gaska, K.
    Chalmers Univ Technol, SE-41296 Gothenburg, Sweden..
    Karlsson, Mattias E.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Hillborg, H.
    ABB AB, Corp Res, Power Technol, SE-72178 Vasteras, Sweden..
    Gedde, Ulf W
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Precision electric characterization of LDPE specimens made by different manufacturing processes2018Ingår i: CHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application, Institute of Electrical and Electronics Engineers (IEEE), 2018, artikel-id 8641846Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work introduces two measurement techniques for precision determination of ultra-low conductivity and accurate characterization of dielectric frequency response for the assessments of polymeric materials used in HVDC insulations. To demonstrate the proposed methods, electrical properties of four different low density polyethylene (LDPE) specimens, obtained by different manufacturing processes were characterized. Results obtained from dc conductivity measurements revealed clear separation of the conduction current levels in the studied specimens. Dielectric losses obtained from the frequency response measurements agrees well with the differences observed in the measured conductivities. This study concludes that the different manufacturing processes have a significant impact on materials electric properties and these parameters can be characterized with precision beyond the existing instruments' specification by using the proposed methods.

  • 594.
    Xu, Yunsheng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hua, Geng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Isosorbide as Core Component for Tailoring Biobased Unsaturated Polyester Thermosets for a Wide Structure- Property Window2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 7, s. 3077-3085Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 595.
    Xu, Yunsheng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    One-Pot Synthesis of Lignin Thermosets Exhibiting Widely Tunable Mechanical Properties and Shape Memory Behavior2019Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 15, s. 13456-13463Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of kraft lignin based thermosets were successfully synthesized by a one-pot heat curing method composed of lignin, PEG400, and citric acid through esterification reactions with water as the only produced byproduct. The polyester thermosets were prepared by varying the ratio of lignin and PEG400 in combination with citric acid as the cross-linker. Lignin and PEG400 were chosen as the rigid and soft segments, respectively, to tailor the thermal mechanical properties of the thermosets. An increase of lignin content from 20 to 40 wt % facilitated an increase in the cross-linking density and aromatic content. This was reflected in the storage modulus at 25 degrees C, which increased from 5.7 to 2000 MPa, and the glass transition temperature, which increased from -0.3 to 102 degrees C. At the same time, the tensile strength changed from 1.2 to 34.3 MPa. The mechanical properties were, thus, tunable from flexible to rigid, demonstrating a significantly high storage modulus and tensile strength for a biobased thermoset. Furthermore, a superb thermally stimulated shape memory property was illustrated. This is promising for the use of commercial kraft lignin as a building block for versatile applications.

  • 596.
    Xu, Yunsheng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Synthesis of bio-based and recyclable thermosets2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Artikel i tidskrift (Övrigt vetenskapligt)
  • 597.
    Xuan, Wenxiang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Levulinic Acid as a Versatile Building Block for Plasticizer Design2019Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 14, s. 12552-12562Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The large potential of utilizing green platform chemicals such as levulinic acid, glycerol, and ethylene glycol as building blocks for the design of high-performance biobased plasticizers was demonstrated. From these green platform chemicals, esters with ketal or ketone functionalities and linear or branched structures were carefully designed and synthesized via a mild and solvent-free route and characterized by H-1 NMR, C-13 NMR, and FTIR. The effect of the structural combinations on the performance as plasticizers for polylactide (PLA), including migration resistance, was followed by a series of characterization techniques. The levulinates with ketone end-groups exhibited large capability to lower the glass transition temperature (T-g) of PLA (to 15 degrees C by 20 wt % plasticizer). Ketal end-groups provided additional thermal stability to the plasticizers, but their ability to lower T-g was not as good as that of ketone end-groups. Significantly improved flexibility reaching 546% elongation at break was achieved by the addition of 20 wt % ethylene glycol dilevulinate, as compared to 5% elongation at break for neat PLA. The structural differences for the plasticizers resulted in different degrees of hydrophobicity, which influenced the migration tendency of the plasticizers and also the hydrolysis rate of PLA. The branched ester structure with ketal end-groups maintained the processing window of PLA, but also lowered the hydrolysis rate of PLA in an accelerated migration test. In general, performance comparable to that of the reference plasticizer acetyl tributyl citrate (ATBC) was demonstrated, offering promise for a family of plasticizers derivable from green platform chemicals.

  • 598. Yadav, A.
    et al.
    Benyahia Erdal, Nejla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Nandan, B.
    Srivastava, Vaibhav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Cellulose-Derived Nanographene Oxide Reinforced Macroporous Scaffolds of High Internal Phase Emulsion-Templated Cross-Linked Poly(ϵ-caprolactone)2020Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, nr 2, s. 589-596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose-derived nanographene oxide (nGO)-type carbon dot reinforced porous scaffolds of poly(epsilon-caprolactone) (PCL) were developed as templates from high internal phase emulsions (HIPE). The mechanical strength, structural integrity, and reusability of the scaffolds were enhanced via in situ cross-linking. An oil-in-oil (o/o) HIPE of epsilon-caprolactone monomer (CL) was made for this purpose, and the ring-opening polymerization of a continuous phase comprised of CL, catalyst (Sn(Oct)(2)), and cross-linker (bis(caprolactone-4-yl)) (BCY) was carried out. The functionalization of scaffolds with nGO was assessed along with its role as an effective Pickering stabilizer of the HIPEs. The pore size and porosity of the scaffolds were governed by HIPE morphology, which in turn was controlled by the amount of nGO and the volume fraction of the dispersed phase. The nGO-functionalized scaffolds of cross-linked PCL thus prepared were characterized for their morphological structure, mechanical strength, and oil sorption capacity. Enhanced oil adsorption of nGO-functionalized scaffolds proved them to be of higher potency compared to those made of neat PCL. Superior compressive strength and reusability of scaffolds for oil adsorption up to 40 times while maintaining the structural integrity for >= 25 sorption-desorption cycles added extra value to such scaffolds. The scaffolds also had excellent cell viability as evaluated by MG63 osteoblast-like cells and some bioactivity in the form of calcium phosphate mineralization on the surface of the scaffolds.

  • 599.
    Yan, Jinying
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik. Vattenfall AB, Stockholm, SE-169 92, Sweden.
    Karlsson, Anna
    Vattenfall AB, SE-16992 Stockholm, Sweden..
    Zou, Zhi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Dai, Deliang
    Linnaeus Univ, Econ & Stat, SE-35195 Vaxjo, Sweden..
    Edlund, Ulrica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Contamination of heavy metals and metalloids in biomass and waste fuels: Comparative characterisation and trend estimation2020Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 700, artikel-id UNSP 134382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of contaminated biomass and waste fuels is essential for waste management, waste to energy (WtE) and mitigating carbon emissions. The contamination of heavy metals and metalloids is specially concerned by environmental regulation and waste to energy processes. In this study, comparative characterisation is performed for three typical contaminated biomass and waste fuels. i.e. recycled woods, combustible municipal solid waste, and industrial and commercial wastes. The contamination characteristics are further analysed using statistical methods (e.g. significance, correlation, profile, and principal component analyses) to identify specific contamination features, relations among the contaminants and potential contamination sources. Contamination trend is estimated based on the continuously monitoring fuel qualities, the driving forces for regulating and reduction of the contaminations, and potential changes in major contamination sources. The comparative characterisation combined with statistical analyses provides a better way to understand the contamination mechanisms. The approach can also relate the fuel contamination with the contamination sources and their changes for trend estimation. Generally, the toxic heavy metals and metalloids are expected to be significantly reduced due to stricter regulations, but there is no general trend for the reduction of other metals and metalloids because of the complicated changes in contamination sources and waste recycling streams in the near future.

  • 600. Yang, G.
    et al.
    Nilsson, Fritjof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Schubert, D. W.
    Universal and anisotropic simulation platform for the study of electrical properties of conductive polymer composites2019Ingår i: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2055, artikel-id 050012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to carry out a study on the synergistic relationship of variables which could affect the electrical properties of CPC, a universal and anisotropic platform of simulation, containing three simulation modules are explored. The simulation modules are: finite element modelling (FEM), percolation threshold modeling (PTM) and electrical networks modelling (ENM).

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