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  • 501.
    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.

  • 502. 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.

  • 503.
    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.

  • 504.
    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.

  • 505.
    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.

  • 506.
    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)
  • 507.
    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.

  • 508. 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).

  • 509.
    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.

  • 510.
    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.

  • 511.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH Royal institute of technology.
    Eco-friendly Holocellulose Materials for Mechanical Performance and Optical Transmittance2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Cellulosa-baserade material från förnyelsebar råvara kan fungera som ersättning för fossilbaserade plaster. Den utvecklingen skulle underlättas av förbättrade mekaniska egenskaper, optisk transparens och förbättrad miljövänlig profil (återvinning, koldioxidutsläpp, energiåtgång). Material från holocellulosa analyseras, och relationer mellan process, struktur och egenskaper diskuteras.

    Mild delignifiering används för att framställa ramie-fibrer, holocellulosa-fibrer från gran och nanofibriller från holocellulosa. Kemisk sammansättning, molekylvikt, kristallinitet, fiberlängd och diameter, och hållfasthet hos enskilda fibrer studeras. Med hjälp av formpressning, framställs olika typer av material baserade på fibernätverk. Det innefattar pappers-strukturer med 50% porositet, formpressade fibrer, och nanopapper. Biokompositer framställs genom impregnering med metylmetakrylat och polymerisering i närvaro av ett förstärkande nätverk av holocellulosa-fibrer.

    Fiberorientering kvantifieras med 2D röntgenspridning, mekaniska egenskaper mäts genom enaxliga dragprov och optiska egenskaper mäts genom att använda en integrerande sfär. Material från holocellulosa har mycket bättre egenskaper än motsvarande material baserade på blekta fibrer från kraft-processen. Starka effekter från struktur på molekylär, nano och mikroskala diskuteras och analyseras i arbetet.

    För nanofibriller från holocellulosa undersöks kolloidal stabilitet, återdispergering, ytmodifiering och dessutom återvinning och tredimensionell formning av pappersliknande strukturer. Miljövänliga attribut inkluderar högt fiberutbyte, minskat behov av kemisk modifiering och mycket goda återvinnings-prestanda. Förbättrad prestanda hos holocellulosa-material jämfört med kraft-fibrer, beror på effekter från välbevarad cellulosa, och hemicellulosa, liksom strukturell homogenitet på molekylär, nano och fiberskala.

    Publikationen är tillgänglig i fulltext från 2020-11-19 09:42
  • 512.
    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. KTH Royal institute of technology.
    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. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Recycling without Fiber Degradation: Strong Paper Structures for 3D Forming Based on Nanostructurally Tailored Wood Holocellulose FibersManuskript (preprint) (Övrigt vetenskapligt)
  • 513.
    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.

  • 514.
    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.

  • 515.
    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.
    Reid, Michael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Olsén, Peter
    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), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Eco-Friendly Cellulose Nanofibrils Designed by Nature: Effects from Preserving Native StateManuskript (preprint) (Övrigt vetenskapligt)
  • 516.
    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.

  • 517.
    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.

  • 518.
    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.

  • 519.
    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.

  • 520.
    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.

  • 521.
    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.

  • 522.
    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.

  • 523.
    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.

  • 524.
    Zhang, Wei
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Hua, Yong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Wang, Linqin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Zhang, Biaobiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    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.
    Liu, Peng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Leandri, Valentina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Guo, Yu
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Chen, Hong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Gardner, James M.
    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 DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Kloo, Lars
    The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells2019Ingår i: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, nr 9, s. 6768-6779Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.

  • 525.
    Zhang, Wei
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Sadollahkhani, Azar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    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.
    Leandri, Valentina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Mechanistic Insights from Functional Group Exchange Surface Passivation: A Combined Theoretical and Experimental Study2019Ingår i: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, nr 4, s. 2723-2733Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Four different functional groups including amino (-NH2), phosphine (-PH2), hydroxyl (-OH), and thiol (-SH) were combined with POSS (polyhedral oligomeric silsesquioxane) molecules to investigate how functional groups affect the surface passivation of POSS systems. Results from density-functional theory (DFT) calculations indicate that functional group amino (-NH2) with adsorption energy 86 (56) kJ mol(-1) is consistently better than that of thiol (-SH) with adsorption energy 68 (43) kJ mor(-1) for different passivation mechanisms. Theoretical studies on the analogous POSS-OH and POSS-PH2 systems show similar adsorption energies. Two of the systems were also investigated experimentally; aminopropyl isobutyl POSS (POSS-NH2) and mercaptopropyl isobutyl POSS (POSS-SH) were applied as passivation materials for MAPbI(3) (MA = methylammonium) perovskite and (FA)(0.85)(MA)(0.15)Pb(I-3)(0.85)(Br-3)(0)(.15)(FA = formamidinium) perovskite films. The same conclusion was drawn based on the results from contact angle studies, X-ray diffraction (XRD), and the stability of solar cells in ambient atmosphere, indicating the vital importance of choice of functional groups for passivation of the perovskite materials.

  • 526.
    Zhang, Yuning
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Andrén, Oliver C. J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Nordström, R.
    Fan, Yanmiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Malmsten, M.
    Mongkhontreerat, S.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Off-Stoichiometric Thiol-Ene Chemistry to Dendritic Nanogel Therapeutics2019Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, nr 18, artikel-id 1806693Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel platform of dendritic nanogels is herein presented, capitalizing on the self-assembly of allyl-functional polyesters based on dendritic-linear-dendritic amphiphiles followed by simple cross-linking with complementary monomeric thiols via UV initiated off-stoichiometric thiol-ene chemistry. The facile approach enabled multigram creation of allyl reactive nanogel precursors, in the size range of 190–295 nm, being readily available for further modifications to display a number of core functionalities while maintaining the size distribution and characteristics of the master batch. The nanogels are evaluated as carriers of a spread of chemotherapeutics by customizing the core to accommodate each individual cargo. The resulting nanogels are biocompatible, displaying diffusion controlled release of cargo, maintained therapeutic efficacy, and decreased cargo toxic side effects. Finally, the nanogels are found to successfully deliver pharmaceuticals into a 3D pancreatic spheroids tumor model. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • 527.
    Zhao, Yadong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Moser, Carl
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Transparent Composites Made from Tunicate Cellulose Membranes and Environmentally Friendly Polyester2018Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, nr 10, s. 1728-1735Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of optically transparent composites were made by using tunicate cellulose membranes, in which the naturally organized cellulose microfibrillar network structure of tunicate tunics was preserved and used as the template and a solution of glycerol and citric acid at different molar ratios was used as the matrix. Polymerization through ester bond formation occurred at elevated temperatures without any catalyst, and water was released as the only byproduct. The obtained composites had a uniform and dense structure. Thus, the produced glycerol citrate polyester improved the transparency of the tunicate cellulose membrane while the cellulose membrane provided rigidity and strength to the prepared composite. The interaction between cellulose and polyester afforded the composites high thermal stability. Additionally, the composites were optically transparent and their shape, strength, and flexibility were adjustable by varying the formulation and reaction conditions. These composites of cellulose, glycerol, and citric acid are renewable and biocompatible and have many potential applications as structural materials in packaging, flexible displays, and solar cells.

  • 528.
    Zhao, Yadong
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Moser, Carl
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi. Valmet AB, Sundsvall, Sweden..
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Li, Jiebing
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Film formation and performance of different nanocelluloses obtained from different cellulose sources after different preparation processes2017Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Artikel i tidskrift (Övrigt vetenskapligt)
  • 529.
    Zhao, Yadong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Tagami, Ayumu
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Dobele, Galina
    Latvian State Inst Wood Chem, 27 Dzerbenes Str, LV-1006 Riga, Latvia..
    Lindström, Mikael E.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Sevastyanova, Olena
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films2019Ingår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, nr 3, artikel-id 538Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF)-starch mixture to prepare 100% bio-based composite films. The aim was to investigate the impact of lignin structural diversity on film performance. It was confirmed that lignin's distribution in the films was dependent on the polarity of solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The -OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to decrease in thermal stability and increase in Young's modulus of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic -OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol content, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the relationship between the chemical structure of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin's applications in bio-based materials based on their specific characteristics.

  • 530.
    Zheng, Chao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Cellulosic Thermal Insulation with Improved Water Resistance and Fire Retardancy2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Sweden is one of the largest countries by area in Europe, and almost 70% of it is covered by forest. These abundant forest resources benefit the Swedish bioeconomy, but the pulp and paper industry is facing the challenge of a decrease in the demand for printing paper due to a significant shift to electronic media; therefore, it is a priority to use pulp to produce alternative value-added products, such as thermal insulating materials in buildings. Cellulosic thermal insulation can reduce the heating energy consumption of buildings, and decrease the emission of CO2, thus contributing to a sustainable society.

    However, cellulosic thermal insulation needs to overcome its poor water resistance, to lower the risk of fungi and ensure a good interior air quality. In the work described in this thesis, cellulosic insulation materials have been produced from pulp fibers, water, and foaming agent by a foam-forming technique. Hydrophobic extractives isolated from birch outer bark were used to functionalize the insulating materials. These materials showed an improved water resistance due to the intrinsic non-polarity of the extractives, promising thermal insulation properties and fungal resistance.

    Fire retardancy is another challenge for cellulosic thermal insulation, and cellulosic insulation materials were here prepared from formulations containing pulp and commercial fire retardants. Fire test results showed that the materials containing 20% expandable graphite or 25% synergetic fire retardant had a significantly improved fire retardancy, being able to resist a small flame attack for a short period without substantial flame spreading. A study of the mechanism of fire retardancy confirmed that the fire retardants can catalyze the dehydration of pulp and promote the generation of a protective char layer that prevents the materials from further decomposition.

    Bio-based fire-retardant coatings such as sulfonated kraft lignin and nanoclay can provide a more efficient fire-retardant protection on the cellulosic insulation than a fire retardant incorporated in the materials. A nanoclay coating performed the best because of its very good thermal stability. The effective bio-based fire-retardant coating is promising for future use in cellulosic thermal insulation materials.

  • 531.
    Zheng, Chao
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Li, Dongfang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bio-based fire retardant and its application in cellulose-based thermal insulation materials2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 532.
    Zheng, Chao
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Li, Dongfang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Improving fire retardancy of cellulosic thermal insulating materials by coating with bio-based fire retardants2019Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 34, nr 1, s. 96-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sustainable thermal insulating materials produced from cellulosic fibers provide a viable alternative to plastic insulation foams. Industrially available, abundant, and inexpensive mechanical pulp fiber and recycled textile fiber provide potential raw materials to produce thermal insulating materials. To improve the fire retardancy of low-density thermal insulating materials produced from recycled cotton denim and mechanical pulp fibers, bio-based fire retardants, such as sulfonated kraft lignin, kraft lignin, and nanoclays, were coated onto sustainable insulating material surfaces to enhance their fire retardancy. Microfibrillated cellulose was used as a bio-based binder in the coating formula to disperse and bond the fire-retardant particles to the underlying thermal insulating materials. The flammability of the coated thermal insulating materials was tested using a single-flame source test and cone calorimetry. The results showed that sulfonated kraft lignin-coated cellulosic thermal insulating materials had a better fire retardancy compared with that for kraft lignin with a coating weight of 0.8 kg/m(2). Nanoclay-coated samples had the best fire retardancy and did not ignite under a heat flux of 25 kW/m(2), as shown by cone calorimetry and single-flame source tests, respectively. These cost-efficient and bio-based fire retardants have broad applications for improving fire retardancy of sustainable thermal insulating materials.

  • 533.
    Zheng, Chao
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Li, Dongfang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants2019Ingår i: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 135, nr 6, s. 3015-3027Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanism and kinetics of thermal degradation of materials developed from cellulose fiber and synergetic fire retardant or expandable graphite have been investigated using thermogravimetric analysis. The model-free methods such as Kissinger–Akahira–Sunose (KAS), Friedman, and Flynn–Wall–Ozawa (FWO) were applied to measure apparent activation energy (Ea).The increased Ea indicated a greater thermal stability because of the formation of a thermally stable char, and the decreased Ea after the increasing region related to the catalytic reaction of the fire retardants, which revealed that the pyrolysis of fire retardant-containing cellulosic materials through more complex and multi-step kinetics. The Friedman method can be considered as the best method to evaluate the Ea of fire-retarded cellulose thermal insulation compared with the KAS and two methods. A master-plots method such as the Criado method was used to determine the possible degradation mechanisms. The degradation of cellulose thermal insulation without a fire retardant is governed by a D3 diffusion process when the conversion value is below 0.6, but the materials containing synergetic fire retardant and expandable graphite fire retardant may have a complicated reaction mechanism that fits several proposed theoretical models in different conversion ranges. Gases released during the thermal degradation were identified by pyrolysis–gas chromatography/mass spectrometry. Fire retardants could catalyze the dehydration of cellulosic thermal insulating materials at a lower temperature and facilitate the generation of furfural and levoglucosenone, thus promoting the formation of char. These results provide useful information to understand the pyrolysis and fire retardancy mechanism of fire-retarded cellulose thermal insulation.

  • 534.
    Zhong, Qi
    et al.
    Zhejiang Sci Tech Univ, Natl Base Int Sci & Technol Cooperat Text & Consu, Engn Res Ctr Ecodyeing & Finishing Text, Key Lab Adv Text Mat & Mfg Technol,Minist Educ, Hangzhou 310018, Zhejiang, Peoples R China.;Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Mi, Lei
    Zhejiang Sci Tech Univ, Natl Base Int Sci & Technol Cooperat Text & Consu, Engn Res Ctr Ecodyeing & Finishing Text, Key Lab Adv Text Mat & Mfg Technol,Minist Educ, Hangzhou 310018, Zhejiang, Peoples R China..
    Metwalli, Ezzeldin
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Biessmann, Lorenz
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Philipp, Martine
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Miasnikova, Anna
    Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Laschewsky, Andre
    Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany.;Fraunhofer Inst Angew Polymerforschung, Geiselbergstr 69, D-14476 Potsdam, Germany..
    Papadakis, Christine M.
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Cubitt, Robert
    Inst Laue Langevin, 6 Rue Jules Horowitz, F-38000 Grenoble, France..
    Schwartzkopf, Matthias
    Deutsch Elektronen Synchrotron DESY, Photon Sci, Notkestr 85, D-22607 Hamburg, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Wang, Jiping
    Zhejiang Sci Tech Univ, Natl Base Int Sci & Technol Cooperat Text & Consu, Engn Res Ctr Ecodyeing & Finishing Text, Key Lab Adv Text Mat & Mfg Technol,Minist Educ, Hangzhou 310018, Zhejiang, Peoples R China..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat Fachgebiet Phys Weicher Mat, James Franck Str 1, D-85748 Garching, Germany..
    Effect of chain architecture on the swelling and thermal response of star-shaped thermo-responsive (poly(methoxy diethylene glycol acrylate)-block-polystyrene)(3) block copolymer films2018Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 14, nr 31, s. 6582-6594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of chain architecture on the swelling and thermal response of thin films obtained from an amphiphilic three-arm star-shaped thermo-responsive block copolymer poly(methoxy diethylene glycol acrylate)-block-polystyrene ((PMDEGA-b-PS)(3)) is investigated by in situ neutron reflectivity (NR) measurements. The PMDEGA and PS blocks are micro-phase separated with randomly distributed PS nanodomains. The (PMDEGA-b-PS)(3) films show a transition temperature (TT) at 33 degrees C in white light interferometry. The swelling capability of the (PMDEGA-b-PS)(3) films in a D2O vapor atmosphere is better than that of films from linear PS-b-PMDEGA-b-PS triblock copolymers, which can be attributed to the hydrophilic end groups and limited size of the PS blocks in (PMDEGA-b-PS)(3). However, the swelling kinetics of the as-prepared (PMDEGA-b-PS)(3) films and the response of the swollen film to a temperature change above the TT are significantly slower than that in the PS-b-PMDEGA-b-PS films, which may be related to the conformation restriction by the star-shape. Unlike in the PS-b-PMDEGA-b-PS films, the amount of residual D2O in the collapsed (PMDEGA-b-PS)(3) films depends on the final temperature. It decreases from (9.7 +/- 0.3)% to (7.0 +/- 0.3)% or (6.0 +/- 0.3)% when the final temperatures are set to 35 degrees C, 45 degrees C and 50 degrees C, respectively. This temperature-dependent reduction of embedded D2O originates from the hindrance of chain conformation from the star-shaped chain architecture.

  • 535.
    Zhou, Mi
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, SE-41296 Gothenburg, Sweden..
    Sandstrom, Hilda
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Belioka, Maria-Paraskeui
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Mattsson, Tuve
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, SE-41296 Gothenburg, Sweden..
    Investigation of the cohesive strength of membrane fouling layers formed during cross-flow microfiltration: The effects of pH adjustment on the properties and fouling characteristics of microcrystalline cellulose2019Ingår i: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 149, s. 52-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluid dynamic gauging was used to investigate the cohesive strength of the membrane fouling layer formed during cross-flow microfiltration of microcrystalline cellulose. Fouling behaviour was compared at two pH levels (i.e. different surface charges of the particles and membranes) with two membranes (i.e. regenerated cellulose and polyethersulphone). It was found that a suspension at low pH, where the surface charge of the particles is close to zero, resulted in thicker and stronger surface fouling layers (668 +/- 66 mu m thick at a shear stress of 36 Pa for the regenerated cellulose membrane). The permeate flux was reduced by 62% during the first 1000 s. For close-to-neutral pH, where the particles are negatively charged, the fouling layers were thinner and less resistant to shear stress (290 +/- 77 mu m thick at a shear stress of 36 Pa) and the decline of the flux was faster: a 90% decrease was recorded during the initial 1000 s. The differences in flux decline behaviour suggest a more pronounced blocking of the pore openings for the membranes at the higher pH. Similar fouling behaviour was observed for the two membranes. An atomic force microscope equipped with a colloid probe was used to evaluate particle/particle and particle/membrane interactions. Elsevier B.V. All rights reserved.

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