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  • 451.
    Vasileva, Elena
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Baitenov, Adil
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Chen, Hui
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    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.
    Sychugov, Ilya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Yan, Min
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Effect of transparent wood on the polarization degree of light2019Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, nr 12, s. 2962-2965Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

  • 452.
    Vasileva, Elena
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Chen, Hui
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    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.
    Sychugov, Ilya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Yan, Max
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Light Scattering by Structurally Anisotropic Media: A Benchmark with Transparent Wood2018Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, nr 23, artikel-id 1800999Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood (TW) is a biocomposite material with hierarchical structure, which exhibits high optical transmittance and anisotropic light scattering. Here, the relation between anisotropic scattering and the internal structure of transparent wood is experimentally studied and the dependence of scattering anisotropy on material thickness, which characterizes the fraction of ballistic photons in the propagating light, is shown. The limitations of the conven-tional haze, as it is implemented to isotropic materials, are discussed, and a modified characteristic parameter of light scattering—the degree of aniso-tropic scattering is defined. This parameter together with the transport mean free path value is more practical and convenient for characterization of the material scattering properties. It is believed that the generic routine described in this paper can be applied for scattering characterization and comparison of other TW materials of either different thickness, optical quality or based on various wood species.

  • 453.
    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

  • 454.
    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.

  • 455. 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. 

  • 456.
    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.

  • 457.
    Wang, Kun
    et al.
    Tech Univ Munich, Dept Phys, Lehrstuhl Funkt Mat, James Franck Str 1, D-85748 Garching, Germany. .
    Xia, Senlin
    Cao, Wei
    Hohn, Nuri
    Grott, Sebastian
    Kreuzer, Lucas P.
    Schwartzkopf, Matthias
    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
    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.

  • 458.
    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, 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.

  • 459.
    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.

  • 460. 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)
  • 461. 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.

  • 462.
    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.

  • 463.
    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.

  • 464.
    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.

     

  • 465.
    Wei, Xin-Feng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    De Vico, Loris
    Larroche, Pierre
    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 2397-2106Artikel i tidskrift (Refereegranskat)
  • 466.
    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)
  • 467.
    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. 

  • 468.
    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 1873-2321Artikel i tidskrift (Refereegranskat)
  • 469.
    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)
  • 470.
    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. 

  • 471.
    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 DegradationArtikel i tidskrift (Refereegranskat)
  • 472.
    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. 

  • 473.
    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)
  • 474.
    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)
  • 475.
    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.

  • 476.
    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)
  • 477.
    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)
  • 478.
    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)
  • 479.
    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.

  • 480.
    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.

  • 481.
    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.

  • 482. 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.

  • 483.
    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.

  • 484.
    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.

  • 485.
    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.

  • 486.
    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)
  • 487.
    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.

  • 488. 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).

  • 489.
    Yang, Guanda
    et al.
    Friedrich Alexander Univ Erlangen Nuremberg, Inst Polymer Mat, Martensstr 7, D-91058 Erlangen, Germany.
    Nilsson, Fritjof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Schubert, Dirk W.
    A Study of Finite Size Effects and Periodic Boundary Conditions to Simulations of a Novel Theoretical Self-Consistent Mean-Field Approach2019Ingår i: Macromolecular Theory and Simulations, ISSN 1022-1344, E-ISSN 1521-3919, artikel-id 1900023Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a previous work, a very promising mathematical model for predicting the electrical conductivity below the electrical percolation threshold, for both isotropic and anisotropic composites, was published by Schubert. In this work, periodic boundary condition of the simulation is utilized. The results are also compared to the previous work and other theoretical models. The truncated fibers due to finite size of the simulation volume are considered as two individual pieces so that the real aspect ratios will also be taken into consideration. A comparison is made between two groups, in which the length and the radius of the carbon fibers are changed, respectively, under certain aspect ratios. With three different sizes of the simulation volumes, the influence on the results due to the finite size effect is calculated.

  • 490.
    Yang, Guanda
    et al.
    Friedrich Alexander Univ Erlangen Nuremberg, Inst Polymer Mat, Martensstr 7, D-91058 Erlangen, Germany..
    Schubert, Dirk W.
    Friedrich Alexander Univ Erlangen Nuremberg, Inst Polymer Mat, Martensstr 7, D-91058 Erlangen, Germany.;Bavarian Polymer Inst, Key Lab Adv Fiber Technol, Dr Mack Str 77, D-90762 Furth, Germany..
    Qu, Muchao
    Friedrich Alexander Univ Erlangen Nuremberg, Inst Polymer Mat, Martensstr 7, D-91058 Erlangen, Germany..
    Nilsson, Fritjof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Novel Theoretical Self-Consistent Mean-Field Approach to Describe the Conductivity of Carbon Fiber-Filled Thermoplastics: PART II. Validation by Computer Simulation2018Ingår i: Macromolecular Theory and Simulations, ISSN 1022-1344, E-ISSN 1521-3919, Vol. 27, nr 4, artikel-id 1700105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical conductivity of polymeric fiber composites is generally strongly dependent on the constituent conductivities, the fiber filler fraction, the fiber aspect ratio, and on the orientation of the fibers. Even though electrically conductive polymer composites are emerging materials of high scientific and commercial interest, accurate mathematical models for describing such materials are rare. A very promising mathematical model for predicting the electrical conductivity below the electrical percolation threshold, for both isotropic and anisotropic composites, is however recently published by Schubert. The shortcomings of that study are that the model includes so far only one predicted parameter and that it is not sufficiently validated. In the current study, finite element modeling is used to successfully validate the model of Schubert for isotropic fiber composites and to accurately determine the predicted parameter. These theoretical predictions are finally compared with experimental conductivity data for isotropic carbon fiber/poly(methyl methacrylate) (PMMA) composites with fiber filler fractions in the range 0-12 vol% and fiber aspect ratios from 5 to 30. The model forecasts, without any adjustable parameters, are satisfactory close to the experimental data.

  • 491.
    Yang, Xuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berthold, Fredrik
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose2019Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, nr 10, s. 10310-10319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.

  • 492.
    Yang, Xuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berthold, Fredrik
    RISE Res Inst Sweden, Master Samuelsgatan 60, SE-11121 Stockholm, Sweden..
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Preserving Cellulose Structure: Delignified Wood Fibers for Paper Structures of High Strength and Transparency2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 7, s. 3020-3029Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 493.
    Yassin, Mohammed A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fuoco, Tiziana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mohamed-Ahmed, Samih
    Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Mustafa, Kamal
    Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    3D and Porous RGDC-Functionalized Polyester-Based Scaffolds as a Niche to Induce Osteogenic Differentiation of Human Bone Marrow Stem Cells2019Ingår i: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 19, nr 6, artikel-id 1900049Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyester-based scaffolds covalently functionalized with arginine-glycine-aspartic acid-cysteine (RGDC) peptide sequences support the proliferation and osteogenic differentiation of stem cells. The aim is to create an optimized 3D niche to sustain human bone marrow stem cell (hBMSC) viability and osteogenic commitment, without reliance on differentiation media. Scaffolds consisting of poly(lactide-co-trimethylene carbonate), poly(LA-co-TMC), and functionalized poly(lactide) copolymers with pendant thiol groups are prepared by salt-leaching technique. The availability of functional groups on scaffold surfaces allows for an easy and straightforward method to covalently attach RGDC peptide motifs without affecting the polymerization degree. The strategy enables the chemical binding of bioactive motifs on the surfaces of 3D scaffolds and avoids conventional methods that require harsh conditions. Gene and protein levels and mineral deposition indicate the osteogenic commitment of hBMSC cultured on the RGDC functionalized surfaces. The osteogenic commitment of hBMSC is enhanced on functionalized surfaces compared with nonfunctionalized surfaces and without supplementing media with osteogenic factors. Poly(LA-co-TMC) scaffolds have potential as scaffolds for osteoblast culture and bone grafts. Furthermore, these results contribute to the development of biomimetic materials and allow a deeper comprehension of the importance of RGD peptides on stem cell transition toward osteoblastic lineage.

  • 494.
    Ye, Xinchen
    et al.
    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.
    Langton, Maud
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    On the role of peptide hydrolysis for fibrillation kinetics and amyloid fibril morphology2018Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, nr 13, s. 6915-6924Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Self-assembly of proteins into amyloid-like nanofibrils is not only a key event in several diseases, but such fibrils are also associated with intriguing biological function and constitute promising components for new biobased materials. The bovine whey protein beta-lactoglobulin has emerged as an important model protein for the development of such materials. We here report that peptide hydrolysis is the rate-determining step for fibrillation of beta-lactoglobulin in whey protein isolate. We also explore the observation that beta-lactoglobulin nanofibrils of distinct morphologies are obtained by simply changing the initial protein concentration. We find that the morphological switch is related to different nucleation mechanisms and that the two classes of nanofibrils are associated with variations of the peptide building blocks. Based on the results, we propose that the balance between protein concentration and the hydrolysis rate determines the structure of the formed nanofibrils.

  • 495.
    Ye, Xinchen
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Junel, Kristina
    RISE Bioecon Innventia AB, Drottning Kristinas Vag 61, SE-11486 Stockholm, Sweden..
    Gallstedt, Mikael
    SIG Combibloc, Vasagatan 7, SE-11120 Stockholm, Sweden..
    Langton, Maud
    SLU Swedish Agr Univ, Dept Mol Sci, Box 7015, S-75007 Uppsala, Sweden..
    Wei, Xin-Feng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Protein/Protein Nanocomposite Based on Whey Protein Nanofibrils in a Whey Protein Matrix2018Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 6, nr 4, s. 5462-5469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article describes nanocomposite films with separately grown protein nanofibrils (PNFs) in a nonfibrillar protein matrix from the same protein starting material (whey). Tensile tests on the glycerol-plasticized films indicate an increased elastic modulus and a decreased extensibility with increasing content of PNFs, although the films are still ductile at the maximum PNF content (15 wt %). Infrared spectroscopy confirms that the strongly hydrogen-bonded beta-sheets in the PNFs are retained in the composites. The films appear with a PNF-induced undulated upper surface. It is shown that micrometer-scale spatial variations in the glycerol distribution are not the cause of these undulations. Instead, the undulations seem to be a feature of the PNF material itself. It was also shown that, apart from plasticizing the protein film, the presence of glycerol seemed to favor to some extent exfoliation of stacked beta-sheets in the proteins, as revealed by X-ray diffraction.

  • 496.
    Ye, Xinchen
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Langton, Maud
    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.
    Protein nanofibrils: Preparation, properties, and possible applications in industrial nanomaterials2019Ingår i: Industrial Applications of Nanomaterials, Elsevier, 2019, s. 29-63Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This chapter deals with protein nanofibrils (PNFs), also referred to as amyloid fibrils. This is an emerging field in nanoscience and engineering. Sources for PNFs, ways of making these, including the mechanisms of the fibrillation process, and factors affecting the production process are presented here. Properties of the PNFs themselves as well as properties and preparation of PNF materials in the form of hydrogels, films, and fibers are also described. In this chapter, PNF-based nanocomposites and templates are also considered. Possible applications of PNFs are discussed and put in the perspective of future uses as, or in, industrial nanomaterials.

  • 497.
    Zanao, Marina
    et al.
    Univ Fed Vicosa, Dept Forestry Engn, Vicosa, MG, Brazil..
    Colodette, Jorge L.
    Univ Fed Vicosa, Dept Forestry Engn, Vicosa, MG, Brazil..
    Oliveira, Rubens C.
    Univ Fed Vicosa, Dept Forestry Engn, Vicosa, MG, Brazil..
    Almeida, Diego P.
    Univ Fed Vicosa, Dept Forestry Engn, Vicosa, MG, Brazil..
    Gomes, Fernando J. B.
    Univ Fed Vicosa, Dept Forestry Engn, Vicosa, MG, Brazil..
    de Carvalho, Danila Morais
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Evaluation of Kraft-PS Cooking for Eucalypt and Pine Wood Chip Mixtures2019Ingår i: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 39, nr 3, s. 149-165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study was evaluating polysulfides (PS) as additives in kraft cooking of wood mixtures eucalypt (E) and pine chips (P) wood mixtures, namely: 50E/50P, 70E/30P, and 90E/10P. Bleaching (O(D/A)(EP)D) and refining of pulps were also investigated. The PS addition (1.5 or 3.0%) to the kraft cooking preserved the hemicelluloses resulting increased pulp yield and reduced H-factor. The oxygen delignification was more efficient for chip mixtures containing higher proportion of pine chips, but was not largely affected by the addition of PS. The bleach chemical consumption was not significantly influenced by PS dosage or by the wood chip mixture. The burst and tear indexes were improved by increasing the proportion of pine chips to the mixture, but an opposite effect was observed for refinability, tensile index, and opacity. The kraft-PS pulps showed increased refinability, tensile, and burst strengths in relation the standard pulps, but lower opacities.

  • 498.
    Zenkert, Dan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Johansson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Carbon fibre composites as batteries, sensors, actuators and energy harvesting2019Ingår i: International Conference on Composite Materials ICCM22, 2019Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Reduced mass for improvements in system performance has become a priority for a wide range of applications that requires electrical energy and includes load-bearing components. Use of lightweight materials has been identified as key for successful electrification of future transport solutions. Structure, energy storage and energy distribution are usually subsystems with the highest mass contributions but energy storage and energy distribution devices are structurally parasitic. One creative path forward is to develop composite materials that perform several functions at the same time – multifunctional materials. Combining functions in a single material entity will enable substantial weight savings on the systems level.

    One such concept is a structural battery, a material that simultaneously carry load and stores energy like a battery. Structural batteries employ carbon fibres as structural reinforcement and negative electrode and can also be used as current collectors to save additional weight.

    A number of new physical phenomena when using carbon fibres as battery electrodes have been found which allows for further multi-functionality. These are all based on the fact that carbon fibres intercalated lithium ions as an electrode material. The ion intercalation creates a reversible longitudinal expansion of the carbon fibres which could be used for actuation and morphing. A piezo electrochemical effect couples the electrical potential of the fibre to the strain acting on it, which can be used for sensing purposes. By combining the expansion and the piezo electrochemical effect one can convert mechanical energy to electrochemical energy, providing an energy harvesting function. The long-term vision of this work is to create a composite material that carries load, stores electrical energy, senses its own state, morphs and harvests energy.

  • 499.
    Zhang, Biaobiao
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Valvo, M.
    Fan, Lizhou
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Daniel, Quentin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Zhang, Peili
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Wang, Linqin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Electrocatalytic Water Oxidation Promoted by 3 D Nanoarchitectured Turbostratic Δ-MnOx on Carbon Nanotubes2017Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 22, s. 4472-4478Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of manganese-based water oxidation electrocatalysts is desirable for the production of solar fuels, as manganese is earth-abundant, inexpensive, non-toxic, and has been employed by the Photosystem II in nature for a billion years. Herein, we directly constructed a 3 D nanoarchitectured turbostratic δ-MnOx on carbon nanotube-modified nickel foam (MnOx/CNT/NF) by electrodeposition and a subsequent annealing process. The MnOx/CNT/NF electrode gives a benchmark catalytic current density (10 mA cm−2) at an overpotential (η) of 270 mV under alkaline conditions. A steady current density of 19 mA cm−2 is obtained during electrolysis at 1.53 V for 1.0 h. To the best of our knowledge, this work represents the most efficient manganese-oxide-based water oxidation electrode and demonstrates that manganese oxides, as a structural and functional model of oxygen-evolving complex (OEC) in Photosystem II, can also become comparable to those of most Ni- and Co-based catalysts.

  • 500.
    Zhang, Fuguo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Cong, Jiayan
    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.
    Bergstrand, Jan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Liu, Haichun
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Cai, Bin
    State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT).
    Hajian, Alireza
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Yao, Zhaoyang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Wang, Linqin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Hao, Yan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Yang, Xichuan
    State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT).
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Ågren, Hans
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Widengren, Jerker
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    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. State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT).
    A facile route to grain morphology controllable perovskite thin films towards highly efficient perovskite solar cells2018Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 53, s. 405-414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Perovskite photovoltaics have recently attracted extensive attention due to their unprecedented high power conversion efficiencies (PCEs) in combination with primitive manufacturing conditions. However, the inherent polycrystalline nature of perovskite films renders an exceptional density of structural defects, especially at the grain boundaries (GBs) and film surfaces, representing a key challenge that impedes the further performance improvement of perovskite solar cells (PSCs) and large solar module ambitions towards commercialization. Here, a novel strategy is presented utilizing a simple ethylammonium chloride (EACl) additive in combination with a facile solvent bathing approach to achieve high quality methyammonium lead iodide (MAPbI3) films. Well-oriented, micron-sized grains were observed, which contribute to an extended carrier lifetime and reduced trap density. Further investigations unraveled the distinctively prominent effects of EACl in modulating the perovskite film quality. The EACl was found to promote the perovskite grain growing without undergoing the formation of intermediate phases. Moreover, the EACl was also revealed to deplete at relative low temperature to enhance the film quality without compromising the beneficial bandgap for solar cell applications. This new strategy boosts the power conversion efficiency (PCE) to 20.9% and 19.0% for devices with effective areas of 0.126 cm2 and 1.020 cm2, respectively, with negligible current hysteresis and enhanced stability. Besides, perovskite films with a size of 10 × 10 cm2, and an assembled 16 cm2(5 × 5 cm2 module) perovskite solar module with a PCE of over 11% were constructed.

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