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  • 201.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Fall, Andreas B.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Continuous assembly of aligned nanofibrils into a micro filamentManuskript (preprint) (Övrigt vetenskapligt)
  • 202.
    Håkansson, Karl
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Orientation of nano-fibrillated cellulose in accelerated flowManuskript (preprint) (Övrigt vetenskapligt)
  • 203.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Biointeractive fibres with antibacterial properties: a multilayer build-up study2008Konferensbidrag (Refereegranskat)
  • 204.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Enarsson, Lars-Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Interactions of Hydrophobically Modified Polyvinylamines: Adsorption Behavior at Charged Surfaces and the Formation of Polyelectrolyte Multilayers with Polyacrylic Acid2010Ingår i: ACS Applied Materials & Interfaces, ISSN 1944-8244, Vol. 2, nr 2, s. 425-433Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure and adsorption behaviors of two types of hydrophobically modified polyvinylamines (PVAm) containing substituents of hexyl and octyl chains were compared to a native polyvinylamine sample. The conformation of dissolved polyvinylamines was studied in aqueous salt solutions using dynamic light scattering. Modified PVAm showed hydrodynamic diameters similar to native PVAm, which indicated that all PVAm polymers were present as single molecules in solution. The adsorption of the polyvinylamines, both native and hydrophobically modified, from aqueous solution onto negatively charged silica surfaces was studied in situ by reflectometry and quartz crystal microgravimetry with dissipation. Polyelectrolyte multilayers; (PEM) with up to nine individual layers were formed together with poly(acrylic acid). Obtained PEM structures were rigid and showed high adsorbed amounts combined with low dissipation, with similar results for both the modified and unmodified PVAm. This suggests that electrostatics dominated the PEM formation. At lower salt concentrations, the hydrophobically modified PVAm produced multilayers with low water contents, indicating that secondary interactions induced by the hydrophobic constituents can also have a significant influence on the properties of the formed layers. The surface structure of PEMs with nine individual layers was imaged in dry state using atomic force microscopy in a dynamic mode. Modified PVAm was found to induce a different structure of the PEM at 100 mM, with larger aggregates compared to those of native PVAm. From these results, it is proposed that modified PVAm can induce aggregation within the PEM, whereas PVAm remains as single molecules in solution.

  • 205.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Römling, Ute
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Antibacterial Polyelectrolyte Multilayers on Cellulosic Pulp FibresManuskript (preprint) (Övrigt vetenskapligt)
  • 206.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Römling, Ute
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Biointeractive antibacterial fibres using polyelectrolyte multilayer modification2012Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, nr 5, s. 1731-1741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contact-active antibacterial surfaces are a novel tool in the antibacterial battle. The preparation of such surfaces usually involves harsh reaction conditions and organic solvents. A more sustainable alternative would involve physical adsorption of water-soluble polyelectrolytes using a renewable substrate. Here, highly charged cationic polyvinylamines (PVAm), with or without hydrophobic modifications, have been adsorbed onto the naturally anionic cellulosic wood-fibres. To increase the amount of PVAm, polyelectrolyte multilayers were prepared using polyacrylic acid as the anionic polyelectrolyte. The modified fibres were characterised for PVAm content, water retention and antibacterial properties. The use of multilayers increased the total polymer content without notably reducing the water swelling. The fibres were shown to have excellent bioactive properties and reduced waterborne Escherichia coli and Bacillus subtilis by more than 99.9 %, which is a generally accepted definition of an antibacterial material. A large reduction in bacterial growth was observed upon addition of nutrients, although minor growth was detected after 24 h. The results further show that one adsorbed polymer layer was sufficient to obtain a contact-active surface, which makes the PVAm multilayer system seemingly unique. No polymer leaching from any of the samples was detected, indicating that the fibres work via a contact-active antibacterial mechanism. The results show the feasibility of constructing a sustainable antibacterial material using a renewable substrate and water-based solutions in the material construction process.

  • 207.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Römling, Ute
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Tailoring the effect of antibacterial polyelectrolyte multilayers by choice of cellulosic fiber substrate2013Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 67, nr 5, s. 573-578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a need for new, antibacterial cellulose-based materials. Antibacterial cellulosic fibers with irreversibly attached polyvinylamine (PVAm) and polyacrylic acid (PAA) in multilayers were developed based on a water-based physical adsorption process. The antibacterial substance is thus prevented from leaching, in contrast to materials containing, for example, silver. It was shown on fibers from different sources that the antibacterial effect against both Escherichia coli and Bacillus subtilis can be tailored. The efficiency correlated with the initial fiber charge, which in turn correlated with the amount of adsorbed PVAm. In the case of highly charged fibers, the antibacterial efficacy was more than 99.9%. A sustainable antibacterial material can be obtained in a simple way based on a water-based process.

  • 208.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Römling, Ute
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    The Antibacterial Effect of Contact-Active Multilayers: A Mechanistic ApproachManuskript (preprint) (Övrigt vetenskapligt)
  • 209.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Making biointeractive fibres: Build-up of antibacterial multilayers studied by SPAR2008Konferensbidrag (Refereegranskat)
  • 210.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Antibacterial Fibres2013Ingår i: Pulp Production and Processing: From Papermaking to High-Tech Products / [ed] Valentin Popa, smithers rapra , 2013, 1st, s. 413-438Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 211.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Bacterial-growth inhibiting properties of multilayers formed with modified polyvinylamine2011Ingår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 88, nr 1, s. 115-120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New methods are needed to fight antibiotic-resistant bacteria. One alternative that has been proposed is non-leaching, permanently antibacterial surfaces. In this study, we test multilayers formed with antibacterial cationic polyvinylamine (PVAm) and polyacrylic acid (PAA) in a growth-inhibition assay. Both hydrophobically modified and native PVAm were investigated. Multilayers did reduce the bacterial growth, as compared to single layers. However, the sampling time in the assay was critical, as the treated surface area is a capacity-limiting factor. After 2 h incubation, a maximal growth inhibition of more than 99% was achieved with multilayers. In contrast, after 8 h we observed a maximal growth-inhibition of 40%. At longer incubation times, the surface becomes saturated, which explains the observed time-dependent effectiveness. The polymers giving multilayers with the strongest growth-inhibiting properties were native PVAm and PVAm modified with C(8), which also were the polymers with highest charge density. We therefore conclude that this effect is mainly an electrostatically driven process. Viability staining using a fluorescent stain showed a high viability rate of the adhered bacteria. The multilayers are therefore more bacteriostatic than antibacterial.

  • 212.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Biointeractive fibers: Antibacterial cellulose via polymer adsorption2011Konferensbidrag (Refereegranskat)
  • 213.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Biointeractive fibres with antibacterial properties2010Konferensbidrag (Refereegranskat)
  • 214.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Biointeractive fibres-antibacterial cellulose via polymer adsorption2011Ingår i: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 2011, s. 1378-1379Konferensbidrag (Refereegranskat)
    Abstract [en]

    The world is in desperate need of new methods for controlling microbial growth. Antibacterial surfaces, with antibacterial polymers irreversible attached, is a promising alternative. By targeting the bacterial membrane, the risk of evolving resistant bacteria is reduced. The attachment of the polymers prevents unwanted leaching and keeps a high, active surface concentration. The making of such surfaces does however involve harsh reaction conditions and is thus unsuitable for use in large scale. Using the polyelectrolyte multilayer (PEM) technique we here electrostatically adsorb cationic antibacterial polymers. This takes place in aqueous solutions and in room temperature, making it an appealing alternative. Previous studies performed in our group have focused on model surfaces to get fundamental knowledge about the multilayer properties. Here the PEMs are applied on cellulosic pulp and tested for antibacterial properties against E. coli and B. subtilis. The obtained material was found to be antibacterial against both bacterial strains. These antibacterial fibers, produced in a safe, sustainable process, will give opportunities for new products and new applications.

  • 215.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Contact-active antibacterial multilayers on fibres: a step towards understanding the antibacterial mechanism by increasing the fibre charge2015Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 3, s. 2023-2034Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contact-active antibacterial materials with irreversibly attached antibacterial agents have been developed as an environmentally friendly alternative to traditional biocide treatments. Of particular interest are materials fabricated through the physical adsorption of charged polymers. This simple method allows for the use of water-based processes and materials originating from renewable sources, e.g., cellulosic fibres. Furthermore, by varying the process parameters, such as ionic strength, it is possible to tune the properties of the adsorbed polymer layer. However, the underlying antibacterial mechanism remains obscure, and this hinders the rational design of antibacterial multilayers. To gain further insight into the antibacterial mechanisms of physically adsorbed multilayers of polyvinylamine and polyacrylic acid, the surface charge of cellulose fibres was increased via radical oxidation. This oxidation increased the amount of polymer that was adsorbed and resulted in increased antibacterial efficacy against both Escherichia coli and Bacillus subtilis compared with polymer-modified unoxidised fibres. Electron microscopy analysis of the E. coli adhered to the fibres revealed that the multilayer treatment resulted in elongated bacteria with deformed cell walls. This work demonstrates the importance of electrostatic interaction to the antibacterial effect of polymer-modified fibres.

  • 216.
    Illergård, Josefin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Contact-active antibacterial polyelectrolyte multilayers: The influence of substrate2013Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, s. 515-PMSE-Artikel i tidskrift (Övrigt vetenskapligt)
  • 217.
    Ingverud, Tobias
    et al.
    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.
    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.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    The combination of a dendritic polyampholyte and cellulose nanofibrils – a new type of functional materialManuskript (preprint) (Övrigt vetenskapligt)
  • 218.
    Joby Kochumalayil, Jose
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Bergenstråhle-Wohlert, Malin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Utsel, Simon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Bioinspired and highly oriented clay nanocomposites with a xyloglucan biopolymer matrix: Extending the range of mechanical and barrier properties2013Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, nr 1, s. 84-91Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of clay bionanocomposites requires processing routes with nanostructural control. Moreover, moisture durability is a concern with water-soluble biopolymers. Here, oriented bionanocomposite coatings with strong in-plane orientation of clay platelets are for the first time prepared by continuous water-based processing. Montmorillonite (MTM) and a "new" unmodified biological polymer (xyloglucan (XG)) are combined. The resulting nanocomposites are characterized by FE-SEM, TEM, and XRD. XG adsorption on MTM is measured by quartz crystal microbalance analysis. Mechanical and gas barrier properties are measured, also at high relative humidity. The reinforcement effects are modeled. XG dimensions in composites are estimated using atomistic simulations. The nanostructure shows highly oriented and intercalated clay platelets. The reinforcement efficiency and effects on barrier properties are remarkable and are likely to be due to highly oriented and well-dispersed MTM and strong XG-MTM interactions. Properties are well preserved in humid conditions and the reasons for this are discussed.

  • 219.
    Johansson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Blomberg, Eva
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Lingström, Rikard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Adhesive Interaction between Polyelectrolyte Multilayers of Polyallylamine Hydrochloride and Polyacrylic Acid Studied Using Atomic Force Microscopy and Surface Force Apparatus2009Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, nr 5, s. 2887-2894Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, the adhesion between substrates treated with identical polyelectrolyte multilayers (PEM) from polyallylamine hydrochloride (PAR) and poly(acrylic acid) (PAA) was studied using atomic force microscopy (AFM) and the Surface force apparatus (SFA). The AFM measurements, conducted under wet conditions for PEMs formed at pH 7.5, showed a higher adhesion (pull-off force) when PAH was adsorbed in the outermost layers. There was also a difference depending on the Molecular mass of the polymers, demonstrating a greater adhesion for the low molecular mass combination of polyelectrolytes. Furthermore, die time in contact showed to be of importance, with increasing pull-off forces with contact time at maximum load. The SFA measurements were conducted under dry conditions, at 100% RH, and under wet conditions for PEMs adsorbed at pH 7.5/3.5. The SFA adhesion measurements showed that under dry conditions, the adhesive forces between two high energetic mica substrates were lowered when they were covered by PEMs before the measurements. The thickness of the adsorbed layers was also measured using SFA. This showed that there was a significant swelling when the dry layers were exposed to 100% RH or to wet conditions. The swelling was higher, indicating a less rigid layer, when PAH was adsorbed in the outermost layer than when the PEM was capped with PAA.

  • 220.
    Johansson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Lundström, Lisa
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Norgren, Magnus
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Adsorption Behavior and Adhesive Properties of Biopolyelectrolyte Multilayers formed from Cationic and Anionic Starch2009Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, nr 7, s. 1768-1776Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cationic starch (D.S. 0.065) and anionic starch (D.S. 0.037) were used to form biopolyelectrolyte multilayers. The influence of the solution concentration of NaCl on the adsorption of starch onto silicon oxide substrates and on the formation of multilayers was investigated using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). The wet adhesive properties of the starch multilayers were examined by measuring pull-off forces with the AFM colloidal probe technique. It was shown that polyelectrolyte multilayers (PEM) can be successfully constructed from cationic starch and anionic starch at electrolyte concentrations of 1 mM NaCl and 10 mM NaCl. The water content of the PEMs was approximately 80% at both electrolyte concentrations. However, the thickness of the PEMs formed at 10 mM NaCl was approximately twice the thickness formed at I mM NaCl. The viscoelastic properties of the starch PEMs, modeled as Voigt elements, were dependent on the polyelectrolyte that was adsorbed in the outermost layer. The PEMs appeared to be more rigid when capped by anionic starch than when capped by cationic starch. The wet adhesive pull-off forces increased with layer number and were also dependent oil the polyelectrolyte adsorbed in the outermost layer. Thus, starch PEM treatment has a large potential for increasing the adhesive interaction between solid substrates to levels higher than can be reached by a single layer of cationic starch.

  • 221.
    Johansson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Biopolyelectrolyte Multilayers of Cationic and Anionic Starch as Adhesion Modifiers2010Konferensbidrag (Övrigt vetenskapligt)
  • 222.
    Johansson, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Tailoring the mechanical properties of starch-containing layer-by-layer films2012Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 394, s. 14-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Young's modulus of layer-by-layer (LbL) films containing starch was determined using the recently developed SIEBIMM (strain-induced elastic buckling instability for mechanical measurements) technique. By using cationic starch (CS) in combination with anionic starch (AS), silica nanoparticles (SNP), and nanofibrillated cellulose (NFC), the mechanical properties of these sub-micrometer starch-containing LbL films could be tailored. At 50% relative humidity (RH), the Young's modulus of CS/AS, CS/SNP, and CS/NFC was 0.6 GPa, 0.9 GPa, and 1.8 GPa, respectively, in the 25-85-nm thickness range. As expected for these hygroscopic starch-containing LbL films, the mechanical properties depended on RH. At 0% RH, the Young's modulus was 2-4.5 times higher than at 50% RH. The LbL buildup on polydimethylsiloxane (PDMS) was studied in situ using quartz crystal microgravimetry with dissipation (QCM-D), and atomic force microscopy (AFM) was used to characterize the surface morphology and thickness of the films.

  • 223.
    Josefsson, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The action of fungal cellulases studied using model cellulose films and a quartz crystal microbalanceManuskript (Övrigt vetenskapligt)
  • 224. Josefsson, Peter
    et al.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The physical action of cellulases revealed by a quartz crystal microbalance study using ultrathin cellulose films and pure2008Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, nr 1, s. 249-254Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of fungal cellulases on model cellulose films were studied using a high-resolution quartz crystal microbalance (QCM) sensitive to minute changes of the nanometer thick model cellulose films. It was found that endoglucanases not only produce new end groups but also cause a swelling of the cellulose film. The cellobiohydrolases degraded the films quickly, which was detected as a rapid decrease in the remaining amount of cellulose on the QCM crystal. However, changing viscoelastic properties of the films also indicated a softening of the film during the degradation. A defined mixture of selected cellulases caused a significantly higher rate of degradation than only cellobiohydrolases. Cellulase synergism is discussed with the endoglucanase swelling effects and film softening added.

  • 225.
    Josefsson, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlström, Katarina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Endoglucanase treatment of cellulose fibers improves the fiber/fiber interaction, but weakens the fiber strengthManuskript (Övrigt vetenskapligt)
  • 226.
    Josefsson, Peter
    et al.
    KTH.
    Wågberg, Lars
    KTH.
    Henriksson, Gunnar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    CELL 114-Mode of action of fungal cellulases studied using model cellulose films and a quartz crystal microbalance2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 233, s. 773-773Artikel i tidskrift (Övrigt vetenskapligt)
  • 227.
    Kaldéus, Tahani
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Nordenström, Malin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Insights into the EDC-mediated PEGylation of cellulose nanofibrils and their colloidal stability2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 181, s. 871-878Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    EDC-mediated coupling has frequently been utilized to poly(ethylene glycol) functionalize (PEGylate) cellulose-based materials, but no work has previously been reported on the direct N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC)-mediated PEGylation of cellulose nanofibrils (CNF). Herein, we report the first study where CNF has been directly sterically stabilized with amine-terminated PEG employing N-hydroxysuccinimide (NHS)-assisted EDC-coupling. This work has shown that this coupling reaction is highly sensitive to the reaction conditions and purification procedures, and hence an optimized coupling protocol was developed in order to achieve a reaction yield. Elemental analysis of the nitrogen content also showed the successful PEGylation. It was also shown that a surprisingly low PEGylation (1%) is sufficient to significantly improve the colloidal stability of the PEGylated samples, which reached dispersion-arrested-state-transitions at higher concentrations than neat CNF. The colloidal stability was preserved with increasing ionic strength, when comparably long polymer chains were grafted, targeting only 1% PEGylation.

  • 228.
    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)
  • 229.
    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)
  • 230.
    Karabulut, Erdem
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Marais, Andrew
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wet-resilient, low density aerogels from nanofibrillated cellulose: Their properties and use as templates for layer-by-layer modification2013Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, s. 73-PMSE-Artikel i tidskrift (Övrigt vetenskapligt)
  • 231.
    Karabulut, Erdem
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ankerfors, Mikael
    Material Processes, Innventia AB, Stockholm, Sweden.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Adhesive Layer-by-Layer Films of Carboxymethylated Cellulose Nanofibril Dopamine Covalent Bioconjugates Inspired by Marine Mussel Threads2012Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, nr 6, s. 4731-4739Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The preparation of multifunctional films and coatings from sustainable, low-cost raw materials has attracted considerable interest during the past decade. In this respect, cellulose-based products possess great promise due not only to the availability of large amounts of cellulose in nature but also to the new classes of nanosized and well-characterized building blocks of cellulose being prepared from trees or annual plants. However, to fully utilize the inherent properties of these nanomaterials, facile and also sustainable preparation routes are needed. In this work, bioinspired hybrid conjugates of carboxymethylated cellulose nanofibrils (CNFC) and dopamine (DOPA) have been prepared and layer-by-layer (LbL) films of these modified nanofibrils have been built up in combination with a branched polyelectrolyte, polyethyleneimine (PEI), to obtain robust, adhesive, and wet-stable nanocoatings on solid surfaces. It is shown that the chemical functionalization of CNFCs with DOPA molecules alters their conventional properties both in liquid dispersion and at the interface and also influences the LbL. film formation by reducing the electrostatic interaction. Although the CNFC-DOPA conjugates show a lower colloidal stability in aqueous dispersions due to charge suppression, it was possible to prepare the LbL films through the consecutive deposition of the building blocks. Adhesive forces between muttilayer films prepared using chemically functionalized CNFCs and a silica probe are much stronger in the presence of Fe3+ than those between a multilayer film prepared from unmodified nanofibrils and a silica probe. The present work demonstrates a facile way to prepare chemically functionalized cellulose nanofibrils whereby more extended applications can produce novel cellulose-based materials with different functionalities.

  • 232.
    Karabulut, Erdem
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Design and characterization of cellulose nanofibril-based freestanding films prepared by layer-by-layer deposition technique2011Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 7, nr 7, s. 3467-3474Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freestanding layer-by-layer (LbL) films of anionic carboxymethylated cellulose nanofibrils (NFC) and a cationic branched polyelectrolyte, polyethyleneimine (PEI) have been prepared and characterized in terms of their structural and mechanical properties. The consecutive build-up of PEI and NFC on a hydroxylated and trifunctional organosilane-coated silicon substrate was monitored with X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance with dissipation (QCM-D) and dual polarization interferometry (DPI) techniques. QCM-D and DPI measurements showed that the formation of each layer was fairly rapid and that the thickness of the NFC layers was larger than that of the PEI layers. The results also showed a linear to exponential growth with increasing layer number. The functionalization of the surface with trichlorosilanes did not significantly change the build-up of the LbL structures but it made it possible to easily peel off the formed films from the substrate. The stratified cross-sectional image of the (PEI/NFC)(150) freestanding film was imaged with field-emission scanning electron microscopy (FE-SEM) and the thickness of (PEI/NFC)(150) was measured to be about 5 mu m. Surface morphologies of the LbL films showed a randomly oriented nanofibrillar structure with an average surface roughness of ca. 9 nm. Uniaxial tensile tests on the freestanding LbL films showed that the introduction of polyelectrolytes into the nanofibrillar network increased the modulus, strain-at-break and stress-at-break, probably as a consequence of the softening of the cellulose film under absolutely dry conditions allowing for some movement of the fibrils before breakage of the film.

  • 233.
    Karabulut, Erdem
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wet-stability of nanofibrillated cellulose-based aerogels controlled by chemical functionalization and layer-by-layer self-assembly2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Artikel i tidskrift (Övrigt vetenskapligt)
  • 234.
    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)
  • 235.
    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)
  • 236.
    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)
  • 237.
    Karlsson, Pernilla
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pendergraph, Samuel A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Larsson, Tomas
    Innventia AB, Stockholm, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cellulose model probes for fundamental research on adhesion, swelling and adsorption2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikel i tidskrift (Övrigt vetenskapligt)
  • 238.
    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)
  • 239.
    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.

  • 240.
    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)
  • 241.
    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.

  • 242. Khan, Z. U.
    et al.
    Edberg, J.
    Hamedi, Mahiar M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gabrielsson, R.
    Granberg, H.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Engquist, I.
    Berggren, M.
    Crispin, X.
    Thermoelectric Polymers and their Elastic Aerogels2016Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin.

  • 243.
    Kishani, Saina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Escalante, Alfredo
    Univ Guadalajara, Wood Cellulose & Paper Res, Guadalajara, Jalisco, Mexico..
    Toriz Gonzalez, Guillermo
    Univ Guadalajara, Wood Cellulose & Paper Res, Guadalajara, Jalisco, Mexico.;Chalmers Univ Technol, WWSC, Gothenburg, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gatenholm, Paul
    Chalmers Univ Technol, Chem Biol Engn Biopolymer, Gothenburg, Sweden..
    Solution/aggregation behavior of spruce xylan as function of isolation/purification conditions2017Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Artikel i tidskrift (Övrigt vetenskapligt)
  • 244.
    Kishani, Saina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Xu, Wenyang
    Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
    Xu, Chunlin
    Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Solubility of Softwood Hemicelluloses2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 4, s. 1245-1255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is demonstrated that the molecular solubility of softwood hemicelluloses is significantly influenced by pretreatment of the fibers, extraction, and downstream processing. To quantify these effects, four hemicellulose samples were extracted from different thermomechanical pulps of Norway spruce. The molecular solubility of the samples was characterized by size and molar mass distributions, and the morphology of the molecules was studied using high resolution microscopy techniques. All extracted samples were well dispersed in aqueous media creating transparent dispersions, but dynamic light scattering measurements showed that molecular solubility can only be achieved using specific pretreatments and extractions. The procedure yields acetylated galactoglucomannan (AcGGM)-rich hemicelluloses with an average molar mass of 21-35 kDa and a diameter up to 10 nm but also shows that water is a poor solvent for this sample since an association is detected as soon as the concentration is about 20 g/L. These associated hemicellulose dispersions are still absolutely dear on visual inspection, underlining the need for careful measurement when assessing the solubility of wood hemicelluloses.

  • 245.
    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)
  • 246.
    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)
  • 247.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Superior Flame-Resistant Cellulose Nanofibril Aerogels Modified with Hybrid Layer-by-Layer Coatings2017Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 34, s. 29082-29092Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanometer thin films consisting of cationic chitosan (Ch), anionic poly(vinylphosphonic acid) (PVPA), and anionic montmorillonite clay (MMT) are deposited on highly porous, wet-stabilized cellulose nanofibril (CNF) aerogels via the layer-by-layer (LbL) technique. Model experiments with silicon oxide surfaces are used to study the details of LbL formation and the multilayer structure. Formation of layers on the aerogels is also investigated as a function of solution concentration by use of polyelectrolyte titration. Thermogravimetric analysis indicates that the LbL coating significantly improves thermal stability of the CNF aerogel. Horizontal flame test shows that aerogels coated with five quadlayers of Ch/PVPA/Ch/MMT, using solutions/dispersion of high concentration, are able to self-extinguish immediately after removal of flame, and LbL-coated aerogels do not ignite under heat flux (35 kW/m(2)) in cone calorimetry. The LbL-coated aerogel can prevent flame penetration from a torch focused on the surface, achieving temperature drops up to 650 degrees C across the 10 mm thick specimen for several minutes. LbL treatment is hence a rapid and highly effective way to specifically tailor the surface properties of CNF aerogels in order to confer unprecedented flame-retardant characteristics.

  • 248.
    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.

  • 249.
    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)
  • 250.
    Köklükaya, Oruç
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carosio, Federico
    Grunlan, Jaime C.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Flame-Retardant Paper from Wood Fibers Functionalized via Layer-by-Layer Assembly2015Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, nr 42, s. 23750-23759Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The highly flammable character of cellulose-rich fibers from wood limits their use in some advanced materials. To suppress the flammability and introduce flame-retardant properties to individual pulp fibers, we deposited nanometer thin films consisting of cationic chitosan (CH) and anionic poly(vinylphosphonic acid) (PVPA) on fibers using the layer-by-layer (LbL) technique. The buildup of the rnultilayer film was investigated in the presence and absence of salt (NaCl) using model cellulose surfaces and a quartz crystal microbalance technique. Fibers were then treated with the same strategy, and the treated fibers were used to prepare paper sheets. A horizontal flame test (HFT) and cone calorimetry were conducted to evaluate the combustion behavior of paper sheets as a function of the number of bilayers deposited on fibers. In HFT, paper made of fibers coated with 20 CH/PVPA bilayers (BL), self-extinguished the flame, while uncoated fibers were completely consumed. Scanning electron microscopy of charred paper after HFT revealed that a thin shell of the charred polymeric multilayer remained after the cellulose fibers had been completely oxidized. Cone calorimetry demonstrated that the phosphorus-containing thin films (20 BL is similar to 25 nm) reduced the peak heat release rate by 49%. This study identifies a unique and highly effective way to impart flame-retardant characteristic to pulp fibers and the papers made from these fibers.

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