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  • 201.
    Kaldéus, Tahani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Nordenström, Malin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Erlandsson, Johan
    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, Fiberteknologi.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Redispersibility properties of dried cellulose nanofibrils - influence on structure and mechanical propertiesManuskript (preprint) (Övrigt vetenskapligt)
  • 202.
    Kaldéus, Tahani
    et al.
    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.
    Nordenström, Malin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Erlandsson, Johan
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Redispersibility properties of dried cellulose nanofibrils - influence on structure and mechanical properties2019Ingår i: Artikel i tidskrift (Övrigt vetenskapligt)
  • 203.
    Kaldéus, Tahani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Telaretti Leggieri, Maria Rosella
    Cobo Sanchez, Carmen
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    All-aqueous SI-ARGET ATRP from cellulose nanofibrils using hydrophilic and hydrophobic monomers2019Ingår i: Artikel i tidskrift (Övrigt vetenskapligt)
  • 204.
    Kaldéus, Tahani
    et al.
    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.
    Träger, Andrea
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Berglund, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lo Re, Giada
    Chalmers University of Technology.
    Molecular engineering of cellulose-PCL bio-nanocomposite interface by reactive amphiphilic copolymer nanoparticles2019Ingår i: Artikel i tidskrift (Refereegranskat)
  • 205.
    Kaldéus, Tahani
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Träger, Andrea
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lo Re, Giada
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles2019Ingår i: ACS NANO, Vol. 13, nr 6, s. 6409-6420Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A molecularly engineered water-borne reactive compatibilizer is designed for tuning of the interface in melt-processed thermoplastic poly(caprolactone) (PCL)-cellulose nanocomposites. The mechanical properties of the nanocomposites are studied by tensile testing and dynamic mechanical analysis. The reactive compatibilizer is a statistical copolymer of 2-(dimethylamino)ethyl methacrylate and 2-hydroxy methacrylate, which is subsequently esterified and quaternized. Quaternized ammonium groups in the reactive compatibilizer electrostatically match the negative surface charge of cellulose nanofibrils (CNFs). This results in core-shell CNFs with a thin uniform coating of the compatibilizer. This promotes the dispersion of CNFs in the PCL matrix, as concluded from high-resolution scanning electron microscopy and atomic force microscopy. Moreover, the compatibilizer "shell" has methacrylate functionalities, which allow for radical reactions during processing and links covalently with PCL. Compared to the bio-nanocomposite reference, the reactive compatibilizer (<4 wt %) increased Young's modulus by about 80% and work to fracture 10 times. Doubling the amount of peroxide caused further improved mechanical properties, in support of effects from higher cross-link density at the interface. Further studies of interfacial design in specific nanocellulose-based composite materials are warranted since the detrimental effects from CNFs agglomeration may have been underestimated.

  • 206.
    Karim, Zoheb
    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.
    De-Castro, Daniele Oliveira
    KTH.
    Svedberg, A.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH.
    Berglund, Lars
    KTH.
    Forming a cellulose based nanopaper using XPM2017Ingår i: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017, s. 399-407Konferensbidrag (Refereegranskat)
  • 207.
    Karlsson, Josefin
    et al.
    KTH. Royal Inst Technol, S-10044 Stockholm, Sweden..
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Enarsson, Lars-Erik
    KTH.
    Wågberg, Lars
    KTH.
    CELL 283-Making biointeractive fibers: Buildup of antibacterial multilayers studied by QCM-D and SPAR2008Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 235Artikel i tidskrift (Övrigt vetenskapligt)
  • 208.
    Karlsson, Mattias E.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mamie, Yann C.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Calamida, Andrea
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Olsson, Richard
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Synthesis of Zinc Oxide Nanorods via the Formation of Sea Urchin Structures and Their Photoluminescence after Heat Treatment2018Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, nr 17, s. 5079-5087Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A protocol for the aqueous synthesis of ca. 1-mu m-long zinc oxide (ZnO) nanorods and their growth at intermediate reaction progression is presented, together with photoluminescence (PL) characteristics after heat treatment at temperatures of up to 1000 degrees C. The existence of solitary rods after the complete reaction (60 min) was traced back to the development of sea urchin structures during the first 5 s of the precipitation. The rods primarily formed in later stages during the reaction due to fracture, which was supported by the frequently observed broken rod ends with sharp edges in the final material, in addition to tapered uniform rod ends consistent with their natural growth direction. The more dominant rod growth in the c direction (extending the length of the rods), together with the appearance of faceted surfaces on the sides of the rods, occurred at longer reaction times (>5 min) and generated zinc-terminated particles that were more resistant to alkaline dissolution. A heat treatment for 1 h at 600 or 800 degrees C resulted in a smoothing of the rod surfaces, and PL measurements displayed a decreased defect emission at ca. 600 nm, which was related to the disappearance of lattice imperfections formed during the synthesis. A heat treatment at 1000 degrees C resulted in significant crystal growth reflected as an increase in luminescence at shorter wavelengths (ca. 510 nm). Electron microscopy revealed that the faceted rod structure was lost for ZnO rods exposed to temperatures above 600 degrees C, whereas even higher temperatures resulted in particle sintering and/or mass redistribution along the initially long and slender ZnO rods. The synthesized ZnO rods were a more stable Wurtzite crystal structure than previously reported ball-shaped ZnO consisting of merging sheets, which was supported by the shifts in PL spectra occurring at ca. 200 degrees C higher annealing temperature, in combination with a smaller thermogravimetric mass loss occurring upon heating the rods to 800 degrees C.

  • 209.
    Karlsson, Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Swelling of Cellulose Fibrillar Matrices and Gels2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    One of the major challenges of today´s society is to find a sustainable way to create a living based on the resources on earth. It is a challenge that includes a transition from fossil-based materials to renewable/biodegradable raw materials and also the creation of an environmentally friendly circular material flow. In the search for renewable and biodegradable raw materials, the forest has gained renewed interest. In Sweden, 70 % of the area is covered with forest and, together with a long history of a sustainable forestry, this means that there are environmental and economic gains if this resource is utilized in a correct way and research and development into new wood-based materials has advanced significantly during the last decades. The wood component that has gained the most attention is cellulose and due to the ability of cellulose to act as a light-weight reinforcing component in composites and also due to the variability by which cellulose can be modified in order to obtain a wide range of useful properties. One advantage of cellulose-based materials is that they can be processed in water since the cellulose is hydrophilic and is softened by exposure to water. At the same time, this is one of the major drawbacks of cellulose-based materials since their properties deteriorate when exposed to water, whether as moist air or as condensed liquid. To optimize the use of cellulose fibers/fibrils/gels, knowledge of the effect on the inherent properties of cellulose in contact with water needs to be extended. This project has therefore focused on a fundamental understanding of the reasons behind the water uptake/swelling in a cellulose-rich fiber assembly immersed in water.

    The project has included the development and characterization of cellulose model materials in the form of gel (beads) and fibrillar (filaments) networks, for which the swelling was measured as a dimensional change in different aqueous environments. In one of the subprojects, the ion-induced swelling in different cellulose networks was measured on model materials and it was shown that the ion-induced contribution to the swelling was not only dependent on pH and salt concentration in the aqueous solution but also on the stiffness and structure of the network. Thermodynamic models describing gel swelling were used to separate and quantify the osmotic pressure associated with different factors contributing to the total osmotic pressure (ions, mixing and network) of never-dried gel beads. It was thus possible to identify the factor which had a dominant influence in the osmotic pressure and hence most important on the swelling of the systems. Never-dried gel beads showed that the network entropy was the most important factor controlling the swelling of the beads up to a volume fraction of cellulose of 35 %. Above this volume fraction the mixing entropy was found to dominate the swelling. It was also found that the distribution of the total osmotic pressure on these three factors was dependent on the network structure, as the distribution changed when the beads were dried and rewetted compared to the never-dried beads. Finally the de-watering ability of the gel beads in different environments was studied, and also after different modifications targeting the properties shown to have the most dominant effect on the osmotic swelling pressure (ion, mix and network). It was possible to quantify how the gel beads were dewatered to different degrees if e.g. hydrogen was chosen as the counter-ion to the carboxyl groups, if the polarity of the solution was lowered and if the structure of cellulose was changed. This information can, for example, be used to predict how nanocellulose based networks are dewatered under different conditions and this is essential for the preparation of materials based on cellulose nanofibrils.

    Publikationen är tillgänglig i fulltext från 2021-12-31 14:00
  • 210.
    Karlsson, Pernilla
    et al.
    KTH.
    Larsson, Tomas
    Innventia AB, Stockholm, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Cellulose-based gel beads for quantifying the swelling behavior of plant fibers2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 211.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fall, Andreas
    RISE Bioeconomy.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Wågberg, Lars
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    De-watering of Cellulose-based Gel Networks Targeting Different Factors Contributing to the Swelling PressureManuskript (preprint) (Övrigt vetenskapligt)
  • 212.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Hansson, Per
    Uppsala University, Dep. of Pharmacy, Uppsala Biomedical Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Thermodynamics of the Water-Retaining Properties of Cellulose-Based Networks2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 4, s. 1603-1612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Noncrystalline cellulose-based gel beads were used as a model material to investigate the effect of osmotic stress on a cellulosic network. The gel beads were exposed to osmotic stress by immersion in solutions with different concentrations of high molecular mass dextran and the equilibrium dimensional change of the gel beads was studied using optical microscopy. The volume fraction of cellulose was calculated from the volume of the gel beads in dextran solutions and their dry content and the relation between the cellulose volume fraction and the total osmotic pressure was thus obtained. The results show that the contribution to the osmotic pressure from counterions increases the water-retaining capacity of the beads at high osmotic pressures but also that the main factor controlling the gel bead collapse at high osmotic strains is the resistance to the deformation of the polymer chain network within the beads. Furthermore, the osmotic pressure associated with the deformation of the polymer network, which counteracts the deswelling of the beads, could be fitted to the Wall model indicating that the response of the cellulose polymer networks was independent of the charge of the cellulose. The best fit to the Wall model was obtained when the Flory-Huggins interaction parameter () of the cellulose-water system was set to 0.55-0.60, in agreement with the well-established insolubility of high molecular mass β-(1,4)-d-glucan polymers in water.

  • 213.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    Elasticity and Ion-Induced Swelling of Cellulose Fibrillar Networks and GelsManuskript (preprint) (Övrigt vetenskapligt)
  • 214.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden.
    Yu, Shun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Pendergraph, Samuel Allen
    RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden..
    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.
    Hellwig, Johannes
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    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.
    Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 519, s. 119-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Macroscopic beads of water-based gels consisting of uncharged and partially charged beta-(1,4)-D-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.

  • 215.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    EU:s utsläppshandel otillräckligt för flyget.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 216.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    Hyfs och kunskap krävs i debatten om flyg och klimat.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 217.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    KTH måste göra mer för klimatomställningen.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 218.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Enebro, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cellulose and cellulose derivatives in biomedical materials: Tools to propose the chemical structure by mass spectrometry2009Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 237Artikel i tidskrift (Övrigt vetenskapligt)
  • 219.
    Kishani, Saina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Hemicelluloses are a group of natural polysaccharides and one of the main components of wood. The availability and biodegradability of these polymers have created a great interest in developing new bio-based materials or composites from these materials for different end-use purposes. To develop new materials from these polysaccharides with better functionalities, it is essential to understand the fundamental properties of these compounds. The solubility of hemicelluloses is one of these crucial characteristics since the material has to be dissolved in an appropriate solvent if these biopolymers are to be used in, for example, dense and strong films once the solvents are removed. The interaction of these polysaccharides with different solid surfaces is also significantly influenced by their solubility at the surface/water interface and an understanding of this interaction is essential for describing composite formation, since the polysaccharides are most frequently used together with reinforcing materials such as anisotropic cellulose fibers and fibrils.

    In the work described in this thesis, a novel methodology has been developed for characterizing in detail the solubility of the extracted and model mannans, arabinoxylans and xyloglucan polysaccharides. Different chemical structural analyses, chromatography, light scattering and microscopy techniques have been applied to achieve an accurate understanding of the solubility of the polysaccharides in aqueous media. A careful study has been performed to isolate and purify softwood polysaccharides, followed by the preparation of model samples to investigate the influence of processing, structural substitutions and molar mass on the solubility. Association and the phase separation of hemicelluloses have been identified in aqueous media despite their clear and transparent appearance to the naked eye.

    Natural hemicelluloses are used in combination with cellulose as composite materials both to introduce different functionalities and to utilize the great mechanical properties of cellulose fibrils/fibers. Accordingly, there was a great need to study the influence of the solubility on the interaction and adsorption of these polysaccharides at the cellulose/water interface. The adsorption at the cellulose/water interface was indeed affected by the physicochemical structures and solubility of the polysaccharides, and it has been shown that an increasing molar mass and an increasing polymer concentration lead to formation of associated structures and a phase separation at cellulose model surfaces.

    Publikationen är tillgänglig i fulltext från 2020-05-09 11:51
  • 220.
    Kishani, Saina
    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.
    Wohlert, Jakob
    KTH.
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Solubility and adsorption of different xyloglucan fractions to model surfaces2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 221.
    Kittikorn, Thorsak
    et al.
    Prince Songkla Univ, Dept Mat Sci & Technol, Fac Sci, Hat Yai 90112, Thailand..
    Malakul, Raminatun
    Prince Songkla Univ, Dept Microbiol, Fac Sci, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Enhancement of mechanical, thermal and antibacterial properties of sisal/polyhydroxybutyrate-co-valerate biodegradable composite2018Ingår i: JOURNAL OF METALS MATERIALS AND MINERALS, ISSN 0857-6149, Vol. 28, nr 1, s. 52-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignocellulosic biocomposite is a promising biodegradable materials, though improvement of the interfacial adhesion between cellulose fibre and polymer matrix is still challenged. Therefore, this work investigated the effect of propionylation of sisal reinforced fibre in the sisal/polyhydroxybutyrate-co-valerate (PHBV) biocomposite. Propionylation involved esterification substitution of propionic anhydride to hydroxyl group of sisal fibre, where ester group (COOR) of propionylated fibre was successfully observed by Fourier transform Infrared spectroscopy (FTIR). Then mechanical and thermal properties were evaluated and biodegradation characteristics were assessed. The tensile strength and modulus of propionylated sisal/PHBV biocomposite were greater than unmodified sisal/PHBV, which revealed better compatibility at the interface. In addition, propionate moieties of sisal fibre could induce crystalline formation of PHBV, as determined by an increase of crystalline phase. The higher decomposition temperature (Td) and activation energy (Ea) of 155 kJ.mol(-1), determined by thermal gravimetric analyser (TGA), were strong confirmation of good thermal resistance of the propionylated sisal biocomposite. The storage modulus, as characterized by dynamic mechanical thermal analyser (DMTA), also revealed the improvement of stiffness. Bacterial growth tests evaluated the inhibition of bacterial growth on the PHBV biocomposites. It was clear that propionylation of sisal fibre decreased colonization of Staphylococcus aureus (SA) and Escherichia coli (E.coli).

  • 222.
    Koklukaya, Oruc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Flame-Retardant Cellulose Fibre/Fibril Based Materials via Layer-by-Layer Technique2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    According to an analysis conducted by the Swedish Chemicals Inspectorate in 2006, the approximate numbers of fire injuries per year in Sweden are 100 deaths, 700 major and 700 minor injuries.1 Observations also show that there has been an increase in the number of house fires during recent years. One possible explanation can be the increased use of plastics in the building industry and in furniture. The advantages of easy processing, light weight and low cost make plastic materials most prevalent in the market.  However, plastics behave significantly differently from natural materials in the case of fire. Polymeric materials, including rigid polyurethane foams (PU) which are widely used in the building industry due to their insulating properties, are highly flammable and they release heat at a very high rate. In addition, polymeric materials release more harmful smoke, toxic gases and combustion products than natural materials. A house fire typically starts with the ignition of a combustible material. Flames then spread to nearby materials and shortly thereafter the heat radiation generated reaches a point where the contents of the room suddenly and simultaneously ignite. This stage is called a flash over. After this stage, the fire is fully developed and it continues until everything is consumed. The higher rate of heat and smoke production from plastic materials reduces the time to flash over and hence the time to escape from a fire. The traditional flame-retardant treatments are based mainly on halogenated compounds which are classified as gas phase flame-retardants. The halogenated flame-retardants are under severe investigation due to their adverse effect on health and on the environment since they release toxic gases during combustion and they may leach out and accumulate in the food chain.2-3 The restrictions due to growing environmental concerns have been a driving force to develop alternative flame-retardants by using natural and renewable resources. In recent years, the layer-by-layer (LbL) technique has been used as a simple and versatile surface engineering technique to construct functional nanocoatings through the sequential adsorption of polyelectrolytes and charged nanoparticles in an effort to impart flame-retardant characteristics by inhibiting the combustion cycle.4-5 This thesis presents the physical modification of cellulose fibre/fibril based materials as a means of improving flame-retardant properties.

    In the first part of work described in this thesis, the adsorption of polyelectrolyte multilayers onto pulp fibres was investigated as a way to impart flame-retardant characteristics to paper-based materials. It was found that intumescent nanocoatings consisting of nitrogen and phosphorus containing polyelectrolytes such as chitosan (CH) and poly(vinylphosphonic acid) (PVPA) were able to significantly improve the thermal stability and flame-retardant properties of sheets made of LbL-treated fibres, and were able to self-extinguish the flame in the horizontal flame test (HFT). High magnification images revealed that this improvement in flame-retardancy was due to the formation of a coherent char layer on the fibres (Paper I).6 In addition to imparting flame-retardancy by the LbL-coating of polyethylenimine (PEI) and sodium hexametaphosphate (SHMP), it was also possible to improve the mechanical properties of the paper material with this treatment (Paper III).7

    In the second part of the work, wet-stable porous cellulose fibril-based aerogels were developed by freeze-drying and used as a template for the build-up of intumescent nano-brick wall assemblies. The formation of multilayers of CH, PVPA and montmorillonite clay (MMT) was investigated as a function of solution concentration, and it was found that five quadlayers (QL) of CH/PVPA/CH/MMT treated aerogels using 5 g/L solutions of the respective components were able to self-extinguish the flame in HFT and that they showed no ignition under the heat flux of 35 kW/m2 used in cone calorimetry (Paper II).8 In a different application, a novel low density, porous, wet-stable cellulose fibre network was developed using chemically modified cellulose fibres by solvent exchange from water to acetone followed by drying at room temperature. The fibre networks (FN) were modified using the LbL technique to construct a flame-retardant nanocoating consisting of CH, SHMP, and inorganic particles (i.e., MMT, sepiolite (SEP), and colloidal silica (SNP)). The influence of the shape of the nanoparticles on flame-retardancy was investigated and it was found that plate-like and rod-like clays with a high aspect ratio showed self-extinguishing behaviour in HFT. A 5 QL of CH/SHMP/CH/SEP reduced the peak heat release rate and total smoke release by 47% and 43%, respectively, with an addition of only ~8 wt% to FN (Paper IV).

    Finally, non-crystalline cellulose gel beads were used as a substrate for the LbL assembly of CH and SHMP in model studies aimed at identifying the molecular mechanisms responsible for the fire-retardant properties of the LbL structures. The beads were formed by precipitating the dissolved cellulose-rich fibres according to an earlier described procedure,9 and it was shown that these smooth cellulose beads can be utilized as a model substrate to study the influence of LbL chemistry and nanostructure on flame-retardancy. These new types of model systems thus constitute a new important tool for clarifying the mechanism behind flame-retardant nanocoating systems (Paper V).  

    Publikationen är tillgänglig i fulltext från 2020-12-31 10:00
  • 223.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    López Durán, Vernica
    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, Fiberteknologi.
    Development of hybrid coatings to reduce flammability of low density cellulose fiber networks via layer-by-layer assemblyManuskript (preprint) (Övrigt vetenskapligt)
  • 224.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Tailoring flame-retardancy and strength of papers via layer-by-layer treatment of cellulose fibers2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 4, s. 2691-2709Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The layer-by-layer (LbL) technology was used to adsorb polyelectrolyte multilayers consisting of cationic polyethylenimine (PEI) and anionic sodium hexametaphosphate (SHMP) onto cellulose fibers in order to enhance the flame-retardancy and tensile strength of paper sheets made from these fibers. The fundamental effect of PEI molecular mass on the build-up of the multilayer film was investigated using model cellulose surfaces and a quartz crystal microbalance technique. The adsorption of a low (LMw) and a high molecular weight (HMw) PEI onto cellulose fibers and carboxymethylated (CM) cellulose fibers was investigated using polyelectrolyte titration. The fibers were consecutively treated with PEI and SHMP to deposit 3.5 bilayers (BL) on the fiber surfaces, and the treated fibers were then used to prepare sheets. In addition, a wet-strength paper sheet was prepared and treated with the same LbL coatings. Thermal gravimetric analysis of LbL-treated fibers showed that the onset temperature for cellulose degradation was lowered and that the amount of residue at 800 °C increased. A horizontal flame test and a vertical flame test were used to evaluate the combustion behavior of the paper sheets. Papers prepared from both cellulose fibers and CM-cellulose fibers treated with HMw-PEI/SHMP LbL-combination self-extinguished in a horizontal configuration despite the rather low amounts of adsorbed polymer which form very thin films (wet thickness of ca. 17 nm). The tensile properties of handsheets showed that 3.5 BL of HMw-PEI and SHMP increased the stress at break by 100% compared to sheets prepared from untreated cellulose fibers.

  • 225.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Karlsson, Rose-Marie Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    A study of layer-by-layer nanocoatings on model cellulose gel beads to clarify their flame-retardant characteristicsManuskript (preprint) (Övrigt vetenskapligt)
  • 226.
    Koo, Jun Mo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kim, Hojun
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Lee, Minkyung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Park, Seul-A
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jeon, Hyeonyeol
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Shin, Sung-Ho
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Seon-Mi
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Cha, Hyun Gil
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jegal, Jonggeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Byeong-Su
    Yonsei Univ, Dept Chem, Seoul 03722, South Korea..
    Choi, Bong Gill
    Kangwon Natl Univ, Dept Chem Engn, Samcheok 25913, Gangwon Do, South Korea..
    Hwang, Sung Yeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Oh, Dongyeop X.
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Park, Jeyoung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Nonstop Monomer-to-Aramid Nanofiber Synthesis with Remarkable Reinforcement Ability2019Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, nr 3, s. 923-934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aramid nanofibers (ANFs), typically produced by exfoliating aramid microfibers (Kevlar) in alkaline media, exhibit excellent mechanical properties and have therefore attracted increased attention as nanoscale building blocks. However, the preparation of aramid microfibers involves laborious and hazardous processes, which limits the industrial-scale use of ANFs. This work describes a facile and direct monomer-to-ANF synthesis via an as-synthesized intermediate low-molecular-weight poly(p-phenylene terephthalamide) (PPTA) without requiring the environmentally destructive acids and high-order shearing processes. Under the employed conditions, PPTA immediately dissociates and self-assembles into ANFs within a time period of 15 h, which is much shorter than the time of 180 h (not including the Kevlar preparation time) required for the Kevlar-to-ANF conversion. Interestingly, the fabricated ANFs exhibit nanoscale dimensions and thermoplastic polyurethane (TPU) reinforcing effects similar to those of Kevlar-derived ANFs; i.e., a 1.5-fold TPU toughness improvement and a maximum ultimate tensile strength of 84 MPa are achieved at an ANF content of only 0.04 wt %. Remarkable reinforcement ability investigated by comprehensive analytical data comes from ANFs, which disturb ordered hydrogen bonding in hard segments and induce strain hardening along the elongation pathway. Thus, the developed approach paves the way to industrial-scale production of ANFs and related nanocomposites.

  • 227.
    Kousal, Jaroslav
    et al.
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Shelemin, Artem
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Schwartzkopf, Matthias
    Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Polonskyi, Oleksandr
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Hanus, Jan
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Solar, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Vaidulych, Mykhailo
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Nikitin, Daniil
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Pleskunov, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Krtous, Zdenek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Strunskus, Thomas
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Faupel, Franz
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Biederman, Hynek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Choukourov, Andrei
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 38, s. 18275-18281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magnetron discharge in a cold buffer gas represents a liquid-free approach to the synthesis of metal nanoparticles (NPs) with tailored structure, chemical composition and size. Despite a large number of metal NPs that were successfully produced by this method, the knowledge of the mechanisms of their nucleation and growth in the discharge is still limited, mainly because of the lack of in situ experimental data. In this work, we present the results of in situ Small Angle X-ray Scattering measurements performed in the vicinity of a Cu magnetron target with Ar used as a buffer gas. Condensation of atomic metal vapours is found to occur mainly at several mm distance from the target plane. The NPs are found to be captured preferentially within a region circumscribed by the magnetron plasma ring. In this capture zone, the NPs grow to the size of 90 nm whereas smaller ones sized 10-20 nm may escape and constitute a NP beam. Time-resolved measurements of the discharge indicate that the electrostatic force acting on the charged NPs may be largely responsible for their capturing nearby the magnetron.

  • 228.
    Kubyshkina, Elena
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Unge, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. ABB Corporate Research.
    Impact of interfacial structure on charge dynamics in nanocomposite dielectricsManuskript (preprint) (Övrigt vetenskapligt)
  • 229.
    Kubyshkina, Elena
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Unge, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. ABB Corporate Research, Västerås, SE 72178, Sweden.
    Impact of interfacial structure on the charge dynamics in nanocomposite dielectrics2019Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, nr 4, artikel-id 045109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that the chemistry at the interface between nanoparticle and polymer matrix influence charge dynamics in polymer nanocomposite. Applying density functional theory, we investigate the influence of crystal surface termination, silicon treatment, and water and carboxyl defect on the electronic properties of interfaces in MgO-polyethylene nanocomposite. The band offsets between the nanofiller and base matrix materials show a strong dependence on the chemical composition at the interface. Based on the calculated electronic structure, we propose a band alignment model for charge dynamics in nanocomposite dielectrics. The model not only provides a mechanism of reduction of space charge and conductivity but also predicts an increase in thermal stress and susceptibility to the chemical additives. It is suggested that the suppression mechanisms of space charge and conductivity in nanocomposites can be inherently unstable and promote material aging. The results of the study show a need for long-term performance tests of nanocomposite dielectrics.

  • 230.
    Kupka, Vojtech
    et al.
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic..
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ansari, Farhan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Tang, Hu
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, S-10691 Stockholm, Sweden..
    Slouf, Miroslav
    Acad Sci Czech Republ, Inst Macromol Chem, CR-16206 Prague, Czech Republic..
    Vojtova, Lucy
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic.;SCITEG As, U Vodarny 2965-2, Brno 61600, Czech Republic..
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Jancar, Josef
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic.;SCITEG As, U Vodarny 2965-2, Brno 61600, Czech Republic..
    Well-dispersed polyurethane/cellulose nanocrystal nanocomposites synthesized by a solvent-free procedure in bulk2019Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 40, s. E456-E465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyurethane (PU) nanocomposites utilizing cellulose nanocrystals (CNCs) as nanofiller and amorphous PU matrix were synthesized in a novel solvent-free bulk process. A green nanofiller, CNCs, was studied as reinforcement and was further modified by grafting poly(ethylene glycol) (PEG) on the CNC surface (CNC-PEG). Transmission electron microscopy revealed an excellent dispersion of the PEGylated CNC nanoparticles in the PU matrix, whereas as-received CNCs formed agglomerates. The results indicated strong improvements in tensile properties with Young's modulus increasing up to 50% and strength up to 25% for both, PU/CNC and PU/CNC-PEG nanocomposites. The enhanced tensile modulus was attributed to stiff particle reinforcement together with an increase in glass transition temperature.

  • 231.
    Kürten, Charlotte
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    On Catalytic Mechanisms for Rational Enzyme Design Strategies2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Enzymes enable life by promoting chemical reactions that govern the metabolism of all living organisms. As green catalysts, they have been extensively used in industry. However, to reach their full potential, engineering is often required, which can benefit from a detailed understanding of the underlying reaction mechanism.

    In Paper I, we screened for an esterase with promiscuous amidase activity capitalizing on a key hydrogen bond acceptor that is able to stabilize the rate limiting nitrogen inversion. In silicoanalyses revealed the esterase patatin as promising target that indeed catalyzed amide hydrolysis when tested in vitro. While key transition state stabilizers for amide hydrolysis are known, we were interested in increasing our fundamental understanding of terpene cyclase catalysis (Paper II-V). In Paper II, kinetic studies in D2O-enriched buffers using a soluble diterpene cyclase suggested that hydrogen tunneling is part of the rate-limiting protonation step. In Paper III, we performed intense computational analyses on a bacterial triterpene cyclase to show the influence of water flow on catalysis. Water movement in the active site and in specific water channels, influencing transition state formation, was detected using streamline analysis. In Paper IV and V, we focused on the human membrane-bound triterpene cyclase oxidosqualene cyclase. We first established a bacterial expression and purification protocol in Paper IV, before performing detailed in vitroand in silicoanalyses in Paper V. Our analyses showed an entropy-driven reaction mechanism and the existence of a tunnel network in the structure of the human enzyme. The influence of water network rearrangements on the thermodynamics of the transition state formation were confirmed. Introducing mutations in the tunnel lining residues severely affected the temperature dependence of the reaction by changing the water flow and network rearrangements in the tunnels and concomitant the active site.

  • 232.
    Kürten, Charlotte
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Eriksson, Adam
    Maddalo, Gianluca
    Edfors, Fredrik
    Uhlén, Mathias
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Syrén, Per-Olof
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Engineering of water networks in class II terpene cyclases underscores the importance of amino acid hydration and entropy in biocatalysis and enzyme designManuskript (preprint) (Övrigt vetenskapligt)
  • 233. Lang, A. W.
    et al.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    De Keersmaecker, M.
    Shen, D. E.
    Österholm, A.M.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Reynolds, J. R.
    Transparent Wood Smart Windows: Polymer Electrochromic Devices Based on Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate) Electrodes2018Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, nr 5, s. 854-863Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood composites, with their high strength and toughness, thermal insulation, and excellent transmissivity, offer a route to replace glass for diffusely transmitting windows. Here, conjugated-polymer-based electrochromic devices (ECDs) that switch on-demand are demonstrated using transparent wood coated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a transparent conducting electrode. These ECDs exhibit a vibrant magenta-to-clear color change that results from a remarkably colorless bleached state. Furthermore, they require low energy and power inputs of 3 mWh m−2 at 2 W m−2 to switch due to a high coloration efficiency (590 cm2 C−1) and low driving voltage (0.8 V). Each device component is processed with high-throughput methods, which highlights the opportunity to apply this approach to fabricate mechanically robust, energy-efficient smart windows on a large scale. 

  • 234.
    Lange, Heiko
    et al.
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Sevastyanova, Olena
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Crestini, Claudia
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Correlating structural features of lignin with physical properties: Toward a descriptive-predictive database2015Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Artikel i tidskrift (Övrigt vetenskapligt)
  • 235.
    Larsen, Bjarke Strom
    et al.
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark. kytte, Jeppe.
    Skytte, Jeppe
    Svagan, Anna J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Meng-Lund, Helena
    Grohganz, Holger
    Löbmann, Korbinian
    Using dextran of different molecular weights to achieve faster eeze-drying and improved storage stability of lactate dehydrogenase2019Ingår i: Pharmaceutical development and technology (Print), ISSN 1083-7450, E-ISSN 1097-9867, Vol. 24, nr 3, s. 323-328Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freeze-drying of protein formulations is frequently used to maintain otein activity during storage. The freeze-drying process usually quires long primary drying times because the highest acceptable drying mperature to obtain acceptable products is dependent on the glass ansition temperature of the maximally freeze-concentrated solution -g). On the other hand, retaining protein activity during storage is lated to the glass transition temperature (T-g) of the final eeze-dried product. In this study, dextrans with different molecular ight (1 and 40kDa) and mixtures thereof at the ratio 3:1, 1:1, and 1:3 /w) were used as cryo-/lyoprotectant and their impact on the stability the model protein lactate dehydrogenase (LDH) was investigated at evated temperatures (40 degrees C and 60 degrees C). The dextran rmulations were then compared to formulations containing sucrose as yo-/lyoprotectant. Because of the higher T-g values of the dextrans, e primary drying times could be reduced compared to freeze-drying with crose. Similarly, the higher T-g and T-g of dextrans relative to crose led to benefits during storage which was shown through improved otection of LDH activity.

  • 236.
    Larsson, Per A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Linvill, Eric
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Lo Re, Giada
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Östlund, Sören
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ductile and thermoplastic cellulose with novel application and design opportunities2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 237.
    Larsson, Per A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Riazanova, Anastasiia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ciftci, Goksu Cinar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Rojas, Ramiro
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ovrebo, Hans Henrik
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach2019Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 3, s. 1565-1575Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the successful commercialisation of microfibrillated cellulose (MFC) it is of utmost importance to carefully characterise the constituent cellulose particles. This could for instance lead to the development of MFC grades with size distributions tailored for specific applications. Characterization of MFC is challenging due to the heterogeneous chemical and structural nature of MFC. This study describes a fractionation approach that combines two steps of physical sieving of larger particles and a final centrifugation step to separate out the smallest, colloidally stable particles, resulting in four distinctly different size fractions. The properties, such as size and charge, of each fraction were studied, as well as MFC filtration time, film formation, and film properties (mechanical and optical). It was found that virtually all surface charges, determined by polyelectrolyte adsorption, are located in the colloidally stable fraction of the MFC. In addition, the amount of available surface charges can be used as an estimate of the degree of fibrillation of the MFC. The partly fibrillated particles frequently displayed a branching, fringed morphology. Mechanical testing of films from the different fractions revealed that the removal of large particles may be more important for strength than achieving full fibrillation. Overall, this study demonstrates that by controlling the size distribution in MFC grades, property profiles including dewatering time to make films by filtration, rheology, film strength and optical transmittance could be optimised. [GRAPHICS] .

  • 238.
    Larsson, Per Tomas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Innventia AB, Sweden.
    Karlsson, Rose-Marie Pernilla
    Westlund, Per-Olof
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State2017Ingår i: Nanocelluloses: Their Preparation, Properties, and Applications / [ed] Agarwal, UP Atalla, RH Isogai, A, American Chemical Society (ACS), 2017, Vol. 1251, s. 91-112Konferensbidrag (Refereegranskat)
    Abstract [en]

    By combining H-2-NMRD and CP/MAS C-13-NMR measurements of water-based cellulose gels and of water swollen pulps it was possible to estimate the nature of the interior structure of cellulose fibril aggregates. A set of samples with high cellulose purity and low charge was used. The interpretation of data was based on a relaxation model describing the exchange dynamics for deuterium exchange between water molecules and cellulose hydroxyl groups. The theoretical model used made it possible to calculate cellulose surface-to-volume ratios (q-values) from both H-2-NMRD and CP/MAS C-13-NMR data. Good consistency between H-2-NMRD and CP/MAS C-13-NMR data was found. In all investigated samples the cellulose fibril aggregates showed a different degree of "openness" interpreted as the presence of interstitial water inside fibril aggregates. One result also showed that an increased degree of fibril aggregate openness results from the TEMPO-oxidation. Common to all samples was that in the water swollen state water molecules could access part of the fibril aggregate interior.

  • 239.
    Li, Yuanyuan
    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.
    Cheng, Ming
    Jungstedt, Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Xu, Bo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    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.
    Optically Transparent Wood Substrate for Perovskite Solar Cells2019Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 6, s. 6061-6067Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

  • 240.
    Li, Yuanyuan
    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.
    Vasileva, Elena
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Sychugov, Ilya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Popov, Sergei
    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.
    Optically Transparent Wood: Recent Progress, Opportunities, and Challenges2018Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, nr 14, artikel-id 1800059Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Transparent wood is an emerging load-bearing material reinvented from natural wood scaffolds with added light management functionalities. Such material shows promising properties for buildings and related structural applications, including its renewable and abundant origin, interesting optical properties, outstanding mechanical performance, low density, low thermal conductivity, and great potential for multifunctionalization. In this study, a detailed summary of recent progress on the transparent wood research topic is presented. Remaining questions and challenges related to transparent wood preparation, optical property measurements, and transparent wood modification and applications are discussed.

  • 241.
    Lindblad, Margaretha Soderqvist
    et al.
    Sodra Cell AB, R&D, S-43024 Varobacka, Sweden..
    Albertsson, Ann-Christine
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Dahlman, Olof
    STFI Packforsk AB, SE-10044 Stockholm, Sweden..
    Sjogren, John
    PRV, S-10242 Stockholm, Sweden..
    CELL 92-Modified galactoglucomannan from forestry wastewater utilized for oxygen barrier films and hydrogels2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 233, s. 799-799Artikel i tidskrift (Övrigt vetenskapligt)
  • 242.
    Lo Re, Giada
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Engström, Joakim
    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.
    Wu, Qiong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Gedde, Ulf W.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Olsson, Richard
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Improved Cellulose Nanofibril Dispersion in Melt-Processed Polycaprolactone Nanocomposites by a Latex-Mediated Interphase and Wet Feeding as LDPE Alternative2018Ingår i: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, nr 6, s. 2669-2677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports the development of a sustainable and green one-step wet-feeding method to prepare tougher and stronger nanocomposites from biodegradable cellulose nanofibrils (CNF)/polycaprolactone (PCL) constituents, compatibilized with reversible addition fragmentation chain transfer-mediated surfactant-free poly(methyl methacrylate) (PMMA) latex nanoparticles. When a PMMA latex is used, a favorable electrostatic interaction between CNF and the latex is obtained, which facilitates mixing of the constituents and hinders CNF agglomeration. The improved dispersion is manifested in significant improvement of mechanical properties compared with the reference material. The tensile tests show much higher modulus (620 MPa) and strength (23 MPa) at 10 wt % CNF content (compared to the neat PCL reference modulus of 240 and 16 MPa strength), while maintaining high level of work to fracture the matrix (7 times higher than the reference nanocomposite without the latex compatibilizer). Rheological analysis showed a strongly increased viscosity as the PMMA latex was added, that is, from a well-dispersed and strongly interacting CNF network in the PCL.

  • 243.
    Lo Re, Giada
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Sessini, V.
    Wet feeding approach for cellulosic materials/PCL Biocomposites2018Ingår i: Biomass Extrusion and Reaction Technologies: Principles to Practices and Future Potential, American Chemical Society (ACS), 2018, s. 209-226Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In the past decades, cellulosic materials attracted increasing interest for their potential as reinforcement in bioplastics due to their intrinsic strength and light weight, although uniform fiber dispersion is a challenge. Among biodegradable polyesters, polycaprolactone (PCL) has regained attention for its biodegradability in marine environment together with its ductility. Its low strength, petroleum-based origin and comparably high cost, limit the use of PCL. PCL, therefore, is a good candidate for beneficial effect of cellulose material addition for the preparation of biodegradable composites with improved properties. A one-step wet compounding is reported in this chapter to validate a sustainable method to improve the cellulose dispersion in a hydrophobic polymer matrix as PCL. A comparison between cellulosic wood pulp fibers, microfibrillated cellulose and nanofibrils is made to assess the feasibility of the wet feeding approach for the processing of the biocomposites. Assessment of matrix molar mass demonstrated that PCL is insensitive to the presence of the water during the melt compounding. FE-SEM and X-ray tomography was used to characterize the morphology and to evaluate the nanofibrillation. Tensile tests were carried out to evaluate the mechanical properties of the biocomposites. The shortening and dispersion of the cellulose fibers after the melt processing were evaluated. Young's modulus values indicated that the wet feeding approach improve the dispersion of the cellulose and resulted in enhanced mechanical properties of the biocomposites. The beneficial effect of the wet feeding approach was greater for the pulp fibers compared to the microfibrillated cellulose or the nanofibrils due to a more efficient melt processing and more significant effect on the preservation of the fiber length and their aspect ratio.

  • 244.
    Lo Re, Giada
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Spinella, Stephen
    NYU Tandon School of Engineering, Six Metrotech Center, Brooklyn, New York 11201, United States.
    Boujemaoui, Assya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Vilaseca, Fabiola
    BIMATEC Group, Department of Chemical Engineering, Agricultural and Food Technology, University of Girona, C/Maria Aurèlia Capmany 61, 17003 Girona, Spain.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. RISE Bioeconomy, Teknikringen 56, Stockholm, SE-100 44, Sweden.
    Adås, Fredrik
    RISE Bioeconomy, Teknikringen 56, Stockholm, SE-100 44, Sweden.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance2018Ingår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, nr 6, s. 6753-6760Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 245.
    Lodge, Timothy P.
    et al.
    Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA..
    Lenz, Robert W.
    Univ Massachusetts, Amherst, MA 01003 USA..
    Albertsson, Ann-Christine
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    POLY 337-Macromolecules: The editors' perspective2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Artikel i tidskrift (Övrigt vetenskapligt)
  • 246. Lombardo, S.
    et al.
    Chen, Pan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Thielemans, W.
    Wohlert, Jakob
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Svagan, Anna J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Toward Improved Understanding of the Interactions between Poorly Soluble Drugs and Cellulose Nanofibers2018Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, nr 19, s. 5464-5473Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanofibers (CNFs) have interesting physicochemical and colloidal properties that have been recently exploited in novel drug-delivery systems for tailored release of poorly soluble drugs. The morphology and release kinetics of such drug-delivery systems heavily relied on the drug-CNF interactions; however, in-depth understanding of the interactions was lacking. Herein, the interactions between a poorly soluble model drug molecule, furosemide, and cationic cellulose nanofibers with two different degrees of substitution are studied by sorption experiments, Fourier transform infrared spectroscopy, and molecular dynamics (MD) simulation. Both MD simulations and experimental results confirmed the spontaneous sorption of drug onto CNF. Simulations further showed that adsorption occurred by the flat aryl ring of furosemide. The spontaneous sorption was commensurate with large entropy gains as a result of release of surface-bound water. Association between furosemide molecules furthermore enabled surface precipitation as indicated by both simulations and experiments. Finally, sorption was also found not to be driven by charge neutralization, between positive CNF surface charges and the furosemide negative charge, so that surface area is the single most important parameter determining the amount of sorbed drug. An optimized CNF-furosemide drug-delivery vehicle thus needs to have a maximized specific surface area irrespective of the surface charge with which it is achieved. The findings also provide important insights into the design principles of CNF-based filters suitable for removal of poorly soluble drugs from wastewater.

  • 247.
    Lund, Anja
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden..
    van der Velden, Natascha M.
    Delft Univ Technol, Fac Ind Design Engn, NL-2600 AA Delft, Netherlands..
    Persson, Nils-Krister
    Univ Boras, Smart Text, S-50190 Boras, Sweden.;Univ Boras, Swedish Sch Text, S-50190 Boras, Sweden..
    Hamedi, Mahiar M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mueller, Christian
    Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden..
    Electrically conducting fibres for e-textiles: An open playground for conjugated polymers and carbon nanomaterials2018Ingår i: Materials science & engineering. R, Reports, ISSN 0927-796X, E-ISSN 1879-212X, Vol. 126, s. 1-29Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Conducting fibres and yams promise to become an essential part of the next generation of wearable electronics that seamlessly integrate electronic function into one of the most versatile and most widely used form of materials: textiles. This review explores the many types of conducting fibres and yarns that can be realised with conjugated polymers and carbon materials, including carbon black, carbon nanotubes and graphene. We discuss how the interplay of materials properties and the chosen processing technique lead to fibres with a wide range of electrical and mechanical properties. Depending on the choice of conjugated polymer, carbon nanotube, graphene, polymer blend, or nanocomposite the electrical conductivity can vary from less than 10(-3) to more than 10(3) S cm(-1), accompanied by an increase in Young's modulus from 10 s of MPa to 100 s of GPa. Further, we discuss how conducting fibres can be integrated into electronic textiles (e-textiles) through e.g. weaving and knitting. Then, we provide an overview of some of the envisaged functionalities, such as sensing, data processing and storage, as well as energy harvesting e.g. by using the piezoelectric, thermoelectric, triboelectric or photovoltaic effect. Finally, we critically discuss sustainability aspects such as the supply of materials, their toxicity, the embodied energy of fibre and textile production and recyclability, which currently are not adequately considered but must be taken into account to ready carbon based conducting fibres for truly practical e-textile applications.

  • 248.
    Långberg, Marie
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. SWERIM, SE-16407 Kista, Sweden..
    Örnek, Cem
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Zhang, Fan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Cheng, J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Liu, M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Granaes, E.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Wiemann, C.
    Res Ctr Julich, Peter Grunberg Inst PGI 6, D-52425 Julich, Germany..
    Gloskovskii, A.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Matveyev, Y.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Kulkarni, S.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Noei, H.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Keller, T. F.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Univ Hamburg, Phys Dept, D-20355 Hamburg, Germany..
    Lindell, D.
    SWERIM, SE-16407 Kista, Sweden..
    Kivisakk, U.
    AB Sandvik Mat Technol, SE-81181 Sandviken, Sweden..
    Lundgren, E.
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Stierle, A.
    Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Univ Hamburg, Phys Dept, D-20355 Hamburg, Germany..
    Pan, Jinshan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Characterization of Native Oxide and Passive Film on Austenite/Ferrite Phases of Duplex Stainless Steel Using Synchrotron HAXPEEM2019Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, nr 11, s. C3336-C3340Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new measurement protocol was used for microscopic chemical analysis of surface oxide films with lateral resolution of 1 mu m. The native air-formed oxide and an anodic passive film on austenite and ferrite phases of a 25Cr-7Ni super duplex stainless steel were investigated using synchrotron hard X-ray photoemission electron microscopy (HAXPEEM). Pre-deposited Pt-markers, in combination with electron backscattering diffraction mapping (EBSD), allowed analysis of the native oxide on individual grains of the two phases and the passive film formed on the same area after electrochemical polarization of the sample. The results showed a certain difference in the composition of the surface films between the two phases. For the grains with (001) crystallographic face // sample surface, the native oxide film on the ferrite contained more Cr oxide than the austenite. Anodic polarization up to 1000 mV/(Ag/AgCl) in 1M NaCl solution at room temperature resulted in a growth of the Cr- and Fe-oxides, diminish of Cr-hydroxide, and an increased proportion of Fe3+ species. by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

  • 249.
    López Durán, Veronica
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Erlandsson, Johan
    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 teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Larsson, Per A.
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Novel, Cellulose-Based, Lightweight, Wet-Resilient Materials with Tunable Porosity, Density, and Strength2018Ingår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 6, nr 8, s. 9951-9957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Highly porous materials with low density were developed from chemically modified cellulose fibers using solvent-exchange and air drying. Periodate oxidation was initially performed to introduce aldehydes into the cellulose chain, which were then further oxidized to carboxyl groups by chlorite oxidation. Low-density materials were finally achieved by a second periodate oxidation under which the fibers self-assembled into porous fibrous networks. Following a solvent exchange to acetone, these networks could be air-dried without shrinkage. The properties of the materials were tuned by mechanical mixing with a high intensity mixer for different times prior to the second periodate oxidation, which resulted in porosities between 94.4% and 96.3% (i.e., densities between 54 and 82 kg/m(3)). The compressive strength of the materials was between 400 and 1600 kPa in the dry state and between 20 and 50 kPa in the wet state. It was also observed that in the wet state the fiber networks could be compressed up to 80% while still being able to recover their shape. These networks are highly interesting for use in different types of absorption products, and since they also have a high wet integrity, they can be modified with physical methods for different high-value-added end-use applications.

  • 250.
    López Durán, Veronica
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Hellwig, Johannes
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Effect of Chemical Functionality on the Mechanical and Barrier Performance of Nanocellulose Films2018Ingår i: ACS APPLIED NANO MATERIALS, ISSN 2574-0970, Vol. 1, nr 4, s. 1959-1967Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, we have partially modified fibrils chemically to eate a shell of derivatized cellulose that surrounds the crystalline re of native cellulose. Through the different modifications, we aimed creating a toolbox to enable the properties of CNF materials and terials containing CNFs to be tuned to meet specific material demands. total, nine different chemical modifications using different ueous-based procedures were used as chemical pretreatments before CNF oduction through homogenization. Eight of these modifications included riodate oxidation with an average of 27% of the anhydroglucose units the cellulose chain being cleaved into dialdehydes. The presence of dehydes then facilitated a conversion to other functional groups.

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