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  • 151.
    Sommertune, Jens
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Sugunan, Abhilash
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Ahniyaz, Anwar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Stjernberg Bejhed, Rebecca
    Uppsala University, Sweden.
    Sarwe, Anna
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Balceris, Cristoph
    Technische Universität Braunschweig, Germany.
    Ludwig, Frank
    Technische Universität Braunschweig, Germany.
    Posth, Oliver
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Fornara, Andrea
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Polymer/iron oxide nanoparticle composites—A straight forward and scalable synthesis approach2015In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, no 8, p. 19752-19768Article in journal (Refereed)
    Abstract [en]

    Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy.

  • 152.
    Srinivasa, Prashanth
    et al.
    KTH Royal Institute of Technology, Sweden.
    Kulachenko, Artem
    KTH Royal Institute of Technology, Sweden.
    Aulin, Christian
    RISE, Innventia.
    Experimental characterisation of nanofibrillated cellulose foams2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 6, p. 3739-3753Article in journal (Refereed)
    Abstract [en]

    There is a growing interest in applications for nanofibrillated cellulose based materials owing to their exceptional mechanical properties. Nanofibrillated cellulose (NFC) foam is one such derivative which has potential applications in a wide array of fields. Here, we characterise the mechanical properties of two particular high porosity NFC foams (98.13 and 98.96 %) prepared by a freeze drying process. We evaluate their behaviour in uni-axial and bi-axial compression with cyclic loading. The secondary loading cycles reveal complete irreversible damage of the microstructure, with the secondary loading path being characterised by near zero plateau stress. In force controlled tests, negligible hysteresis corroborates the idea that there is no energy dissipation owing to near complete microstructural damage. Furthermore, we observe no indications of preferential orientation of the microstructure in these tests. The stress responses in mutually perpendicular directions are seen to be identical, within statistical considerations. We then utilise the “pseudo-elastic” model developed and adopt it to the case of highly compressible Ogden strain energy formulation with a modified neo-Hookean for the unloading, with a view of fitting a continuum hyperelastic model to the experimental data. The material parameters obtained from uni-axial data are seen to be insufficient to describe the more general bi-axial deformation. The parameters obtained from the bi-axial test describe uni-axial deformation up to stretches of ~0.5 but overestimate the stress levels beyond that point.

  • 153.
    Stepien, M.
    et al.
    Åbo Akademi University, Finland.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Saarinen, J. J.
    Åbo Akademi University, Finland.
    Teisala, H.
    Tampere University of Technology, Finland.
    Tuominen, Mikko
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Haapanen, J.
    Tampere University of Technology, Finland.
    Kuusipalo, J.
    Tampere University of Technology, Finland.
    Mäkelä, J. M.
    Tampere University of Technology, Finland.
    Toivakka, M.
    Åbo Akademi University, Finland.
    Abrasion and compression resistance of liquid-flame-spray-deposited functional nanoparticle coatings on paper2014In: 13th TAPPI Advanced Coating Fundamentals Symposium 2014, TAPPI Press, 2014, p. 68-82Conference paper (Refereed)
    Abstract [en]

    • Liquid flame spray technology enables low-cost, large-scale nanoparticle deposition in roll-to-roll processes for controlling wettability and creating functional surfaces • SiO2 nanocoating has higher abrasion resistance than TiO2 coating, possibly due to better interparticle sintering • Wettability properties of the LFS nanoparticle coated paperboard are partially maintained after abrasion with a paper surface or compression through calendering • The changes in wettability are due to smoothening of the nanoparticle surface Changes in wettability properties during transport and in converting operations can be expected to be small • Challenges: - Nanoparticle release to air and safety aspects are unknown and difficult to quantify • Potential applications: - Printability control - Improved barrier and heat-sealing properties for extrusion coated board - Adhesion promotion in converting - Liquid absorption control in papermaking and converting operations - Functional surfaces, e.g., self-cleaning surfaces - Printed electronics applications - Microfluidics.

  • 154.
    Stepien, M.
    et al.
    Åbo Akademi University, Finland.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Saarinen, J.J
    Åbo Akademi University, Finland.
    Teisala, H.
    Tampere University of Technology, Finland.
    Tuominen, M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Haapanen, J.
    Tampere University of Technology, Finland.
    Kuusipalo, J.
    Tampere University of Technology, Finland.
    Abrasion and Compression Resistance of Liquid-Flame-Spray-Deposited Functional Nanoparticle Coatings on Paper2014Conference paper (Refereed)
    Abstract [en]

    Functional paper surfaces with adjustable wettability can be fabricated by deposition of nanoparticles in a roll-to-roll liquid flame spray (LFS) process. The TiO2 nanoparticle coating creates a superhydrophobic surface with water CAs exceeding 160°, whereas SiO2 nanoparticle coating creates highly hydrophilic surfaces with water CAs as low as 21°. The superhydrophobicity or hydrophilicity is a result of the combined effect of surface structure and surface chemistry of the nanoparticles. Furthermore, the wettability of the TiO2-nanoparticle coated paper can controlled photocatalytically and adjusted with UV-treatment to any water contact angle between 10° to 160°. In the current work, the abrasion and compression resistance of LFS nanoparticle coated paper was investigated with rotary abrasion testing and calendering. Changes in sample properties were analysed with contact angle measurements, atomic force microscopy and high resolution field-emission scanning electron microscopy (FESEM).

  • 155. Stepien, M.
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Saarinen, J.J.
    Teisalo, H.
    Tuominen, M.
    Wear resistance of nanoparticle coatings on paperboard2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 307Article in journal (Refereed)
  • 156.
    Stevanic, J.S.
    et al.
    RISE, Innventia.
    Bergström, E.M.
    Gatenholm, P.
    Berglund, L.
    Salmen, L.
    RISE, Innventia.
    Arabinoxylan/nanofibrillated cellulose composite films2012In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, no 18, p. 6724-6732Article in journal (Refereed)
  • 157.
    Stevanic, J.S.
    et al.
    RISE, Innventia.
    Joly, C.
    Mikkonen, K.S.
    Pirkkalainen, K.
    Serimaa, R.
    Remond, C.
    Toriz, G.
    Gatenholm, P.
    Tenkanen, M.
    Salmen, L.
    RISE, Innventia.
    Bacterial nanocellulose-reinforced arabinoxylan films2011In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, no 2, p. 1030-1039Article in journal (Refereed)
  • 158.
    Sun, Fengzhen
    et al.
    Uppsala University, Sweden.
    Nordli, Henriette R.
    NTNU Norwegian University of Science and Technology, Norway.
    Pukstad, Brita
    NTNU Norwegian University of Science and Technology, Norway ; Trondheim University Hospital, Norway.
    Gamstedt, E. Kristofer
    Uppsala University, Sweden.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Mechanical characteristics of nanocellulose-PEG bionanocomposite wound dressings in wet conditions2017In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 69, p. 377-384Article in journal (Refereed)
    Abstract [en]

    Wood nanocellulose has been proposed for wound dressing applications partly based on its capability to form translucent films with good liquid absorption capabilities. Such properties are adequate for non-healing and chronic wounds where adequate management of exudates is a requirement. In addition, the translucency will allow to follow the wound development without the necessity to remove the dressing from the wound. Understanding the mechanical properties of nanocellulose films and dressings are also most important for tailoring optimizing wound dressing structures with adequate strength, conformability, porosity and exudate management. Mechanical properties are usually assessed in standard conditions (50% relative humidity, RH), which is not relevant in a wound management situation. In this study we have assessed the mechanical properties of three nanocellulose grades varying in the degree of nanofibrillation. The effect of nanofibrillation and of polyethylene glycol (PEG) addition, on the tensile strength, elongation and elastic modulus were assessed after 24 h in water and in phosphate-buffered saline (PBS). The results reveal the behavior of the nanocellulose dressings after wetting and shed light into the development of mechanical properties in environments, which are relevant from a wound management point of view.

  • 159.
    Sundberg, Peter
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Building Technology.
    Grund Bäck, Lina
    RISE - Research Institutes of Sweden, Built Environment, Building Technology.
    Orman, Robin
    Johnson Matthey Technology Centre, UK.
    Booth, Jonathan
    Johnson Matthey Technology Centre, UK.
    Karlsson, Stefan
    RISE - Research Institutes of Sweden, Built Environment, Building Technology.
    Simultaneous chemical vapor deposition and thermal strengthening of glass2018In: 12th International Conference on Coatings on Glass and Plastics (ICCG 12), 2018Conference paper (Other academic)
    Abstract [en]

    The LIMES project (Light Innovative Materials for Enhanced Solar Efficiency), a Solar-ERA.NET project, was a fruitful collaboration to optimize many different properties in state-of-the-art solar glasses for photovoltaic (PV) modules. Here, we present results related to the effectiveness of combining chemical vapor deposition and thermal strengthening of glass in a simultaneous process. The treated glass surfaces gets a markedly increase of Al2O3, which in previous studies has been shown to have a beneficial effect on the mechanical properties. Successful thermal strengthening and in-situ Chemical Vapor Deposition (CVD) have repeatedly been performed on 4 and 2 mm flat glasses. The strengthening level has been quantified using SCALP (Scattered Light Polariscope). The samples were found to have a surface compressive stress in the range of 85-110 MPa which is comparable to the level of conventional thermally strengthened safety glass. The surface mechanical properties of the samples have been investigated by means of nano/microindentation and the strength of glasses has been quantified by ring-on-ring method. The transparency of the samples after washing was characterized by UV-Vis spectroscopy.

    The in-situ CVD thermally strengthened glasses gets an Al2O3 coated surface which exhibits increased crack resistance and increased scratch resistance as compared to traditionally thermally strengthened glass. The nanohardness for low loads, ≤ 1 mN, follow the order thermo-chemically strengthened glass > thermally strengthened glass > annealed float glass. The results of the strength tests show that the 2 mm thin glass were positively affected by the Al2O3 coating while the 4 mm did not show any significant change. The light transmittance of the treated glasses was not markedly reduced. In summary, this novel process show possibilities to increase specific properties, in this case surface mechanical properties, by simultaneous CVD and thermal strengthening.

  • 160.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Controlling the elastic modulus of cellulose nanofibrils hydrogels by crosslinking: a premise for their use in medical applications2014Conference paper (Refereed)
    Abstract [en]

    Cellulose nanofibrils can be utilized as a building block in novel material concepts. One area of particular interest is formation of hydrogels for use in medical applications such as drug delivery and tissue engineering. Compared to bacterial cellulose, which is presently used for some medical applications but is produced through a somewhat inefficient process, cellulose nanofibrils from wood can be produced effectively and in large quantities. Cellulose nanofibrils are nano-scaled fibres with high aspect ratio and strong interactions with water. In order to produce stable macroscopic structures which perform adequately in humid conditions, the nanofibrils must be cross-linked in a controlled way. Several properties are important for a successful utilization of hydrogels for biomedical applications, such as degradation, bio-adhesion, bioactivity, transport through the network and mechanical properties. In the present work focus is set on the mechanical and viscoelastic properties of hydrogels. Hydrogels of oxidized cellulose nanofibrils were formed by crosslinking the nanofibrils through the formation of covalent bonds between the crosslinking molecules and oxidized sites at the nanofibril surfaces. The elastic moduli of the hydrogels were controlled by varying the concentration and the length of the crosslinking molecules. Results from cytotoxicity studies of cellulose nanofibrils will be shown.

  • 161.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Nanocellulose: a promising green flooding additive2014Conference paper (Refereed)
  • 162.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Alexandrescu, L.
    Gatti, A.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Biocompatibility studies of nanofibril structures based on Eucalyptus and Pinus radiata pulp fibres2012Conference paper (Refereed)
  • 163.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Alexandrescu, L.
    Gatti, A.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Belosi, F.
    Verifying the biocompatibility of cellulose nanofibril structures as a first step to develop filters for air-borne nanoparticles2013Conference paper (Refereed)
  • 164.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Alexandrescu, L.
    Manti, Canonico
    Gatti, A.
    Physical, chemical and biological characterization of a new nanostructured filtering membrane2012Conference paper (Refereed)
  • 165.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Salvatori, R.
    Gatti, A.
    Towards novel filter concepts for nanopollution2011Conference paper (Refereed)
  • 166.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toledo, J.
    Toledo, P.G.
    A comparative study of Eucalyptus and Pinus Radiata pulp fibres as raw materials for production of cellulose nanofibrils2011In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 84Article in journal (Refereed)
  • 167.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kirsebom, H.
    Hajizadet, S.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels2011In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6Article in journal (Refereed)
  • 168.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pettersen, S.
    Draget, K.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Controlling the elastic modulus of nanoengineered hydrogels by cross-linking cellulose nanofibrils2013Conference paper (Refereed)
  • 169.
    Syverud, Kristin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Xhanari, K.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Yu, Y.
    Stenius, P.
    Films made of cellulose nanofibrils: surface modification by adsorption of a cationic surfactant and characterization by computer-assisted electron microscopy2011In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 13Article in journal (Refereed)
  • 170.
    Söderberg, D.
    RISE, Innventia.
    Fluid dynamic challenges of future nano cellulose fiber processes2011Conference paper (Refereed)
  • 171. Tanpichai, S.
    et al.
    Quero, F.
    Nogi, M.
    Yano, H.
    Young, R.J.
    Lindström, T.
    RISE, Innventia.
    Sampson, W.W.
    Eichhorn, S.J.
    Effective young's modulus of bacterial and microfibrillated cellulose fibrils in fibrous networks2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 5, p. 1340-1349Article in journal (Refereed)
  • 172.
    Tehrani, Zari
    et al.
    Swansea University, UK.
    Rogstad Nordli, Henriette
    NTNU Norwegian University of Science and Technology, Norway.
    Pukstad, Brita
    NTNU Norwegian University of Science and Technology, Norway; Trondheim University Hospital, Norway.
    Gethin, David T.
    Swansea University, UK.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Translucent and ductile nanocellulose-PEG bionanocomposites-A novel substrate with potential to be functionalized by printing for wound dressing applications2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 93, p. 193-202Article in journal (Refereed)
    Abstract [en]

    There is potential that nanocellulose structures can act as a substrate for biomedical applications in which printing can expand its use as a functionalized biomaterial. Nanocellulose has a variety of advantages, which make the material suitable for use in biomedical devices that include wound dressings. The material does not promote bacterial growth, allows for production of translucent films and provides a moist wound-healing environment. However it is intrinsically brittle so research is needed to develop its flexibility and strength through the addition of plasticisers. In this work, we explore the effect of Polyethylene Glycol (PEG 400) as a plasticizer on nanocellulose film formation and performance. The nanocellulose used was prepared with TEMPO mediated oxidation. We also demonstrated different methods such as laser profilometry and atomic force microscopy to observe the topography and morphology of the films. FTIR, UV-vis spectroscopy was used to look at the characteristics of the nanocellulose films. In addition, the mechanical strength of the films with and without plasticizers was assessed. This led to the formulation of films that included PEG400 at 10-40% by weight. These demonstrated properties that are suitable for wound dressings. Additionally, the PEG modification yielded films that showed a surface morphology adequate for surface modification by printing. Importantly, a cytotoxicity test was performed using Human Dermal Fibroblasts and Human Epidermal Keratinocytes. The results showed no effect on the metabolic activity when fibroblasts were incubated in the presence of films containing 10 and 25% PEG. A reduction was measured in the presence of PEG at 40%. However, no significant cell death was detected in any of the cell-types. Hence, the nanocellulose-PEG films are not considered to be cytotoxic against human skin cells at the concentrations applied in this study.

  • 173.
    Torstensen, Jonathan
    et al.
    Norwegian University of Science and Technology, Norway.
    Helberg, Ragne M. L.
    Norwegian University of Science and Technology, Norway.
    Deng, Liyuan
    Norwegian University of Science and Technology, Norway.
    Gregersen, Öyvind W.
    Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    PVA/nanocellulose nanocomposite membranes for CO2 separation from flue gas2019In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 81, p. 93-102Article in journal (Refereed)
    Abstract [en]

    In this paper, we explore the use of nanocelluloses as an additive to poly (vinyl alcohol) (PVA) nanocomposite membranes for CO2/N2 mixed-gas separation. Our findings are that several types of nanocellulose can be used to improve membrane performance. PVA/cellulose nanocrystals (CNC) nanocomposite membranes have the most promising performance, with increased CO2 permeance (127.8 ± 5.5 GPU) and increased CO2/N2 separation factor (39 ± 0.4) compared to PVA composite membranes, with permeance 105.5 ± 1.9 GPU and separation factor 36 ± 0.5. The performance of PVA/CNC membranes is similar compared to PVA/carbon nanotubes (CNTs) membranes shown earlier. Thus, CNTs can be replaced by CNC that is biodegradable and non-toxic. Investigating several different nanocellulose types reveal that a high nanocellulose charge and small nanocellulose particles are important nanocellulose traits that improve membrane performance. 

  • 174. Ture, H.
    et al.
    Blomfeldt, T.O.J.
    Gällstedt, M.
    RISE, Innventia.
    Hedenqvist, M.S.
    Properties of Wheat-Gluten/Montmorillonite Nanocomposite Films Obtained by a Solvent-Free Extrusion Process2012In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, no 4, p. 1038-1045Article in journal (Refereed)
  • 175. Ture, H.
    et al.
    Blomfeldt, T.O.J.
    Gällstedt, M.
    RISE, Innventia.
    Hedenqvist, M.S.
    Farris, S.
    Nanostructured silica/wheat gluten hybrid materials prepared by catalytic sol-gel chemistry2013In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, no 10, p. 1131-1139Article in journal (Refereed)
  • 176.
    Valdebenito, Fabiola
    et al.
    Center for Advanced Polymers Research, Chile; La Frontera University, Chile.
    Pereira, Miguel
    University of Concepcion, Chile.
    Ciudad, Gustavo
    La Frontera University, Chile.
    Azocar, Laura
    La Frontera University, Chile.
    Briones, Rodrigo
    Center for Advanced Polymers Research, Chile.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. La Frontera University, Chile.
    On the nanofibrillation of corn husks and oat hulls fibres2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 95, p. 528-534Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNF) were isolated from agro-industrial waste (corn husks and oat hulls) and market kraft pulp fibres, and a detailed comparative study was performed. Initially, the raw materials were subjected to a conventional pulping process to remove lignin and hemicelluloses. The chemical pre-treatment was based on 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation and the mechanical treatment was carried out with a high-pressure homogenizer. An extensive characterization of the raw material and of the nanofibrillated celluloses was performed, considering structural and chemical aspects. CNF films were produced for their characterization by optical methods, laser profilometry (LP), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Considering the same pulping and chemical pre-treatment, the analyses indicated that the oxidized corn husks fibres had higher carboxylate content and thus a larger tendency to nanofibrillate compared to the oat hulls fibres. The obtained content of carboxylic acids was directly proportional to the content of cellulose in the assessed samples, confirming the selectivity of the TEMPO-mediated oxidation. The fibrillated corn husks material had a minor fraction of residual fibres (<4%) and homogeneous nanofibril width distribution (<20 nm), which is a major achievement. The homogeneous CNF morphology was confirmed by AFM analysis. Hence, this study demonstrates that the assessed agro-industrial wastes are sustainable resources for production of CNF, which may have a wide range of value-added applications.

  • 177. Wang, M.
    et al.
    Olszewska, A.
    Walther, A.
    Malho, J.-M.
    Schacher, F.H.
    Ruokolainen, J.
    Ankerfors, M.
    RISE, Innventia.
    Laine, J.
    Berglund, L.A.
    Österberg, M.
    Ikkala, O.
    Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 6, p. 2074-2081Article in journal (Refereed)
  • 178.
    Wells, James
    et al.
    National Physical Laboratory, UK; Physikalisch-Technische Bundesanstalt, Germany.
    Kazakova, Olga
    National Physical Laboratory, UK.
    Posth, Oliver
    Physikalisch-Technische Bundesanstalt, Germany.
    Steinhoff, Uwe
    Physikalisch-Technische Bundesanstalt, Germany.
    Petronis, Sarunas
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Bogart, Lara
    Healthcare Biomagnetics Laboratory, UK.
    Southern, Paul
    Healthcare Biomagnetics Laboratory, UK.
    Pankhurst, Quentin
    Healthcare Biomagnetics Laboratory, UK.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Standardisation of magnetic nanoparticles in liquid suspension2017In: Journal of Physics D: Applied Physics, Vol. 50, no 383003, p. 1-25Article in journal (Refereed)
    Abstract [en]

    Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation,spanning a large number of industry sectors from imaging and actuation based applicationsin biomedicine and biotechnology, through large-scale environmental remediation uses suchas water purification, to engineering-based applications such as position-controlled lubricantsand soaps. Continuous advances in their manufacture have produced an ever-growing rangeof products, each with their own unique properties. At the same time, the characterisation ofmagnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpretthe measurement data. In many cases, the stringent requirements of the end-user technologiesdictate that magnetic nanoparticle products should be clearly defined, well characterised,consistent and safe; or to put it another way—standardised. The aims of this document areto outline the concepts and terminology necessary for discussion of magnetic nanoparticles,to examine the current state-of-the-art in characterisation methods necessary for the mostprominent applications of magnetic nanoparticle suspensions, to suggest a possible structurefor the future development of standardisation within the field, and to identify areas and topicswhich deserve to be the focus of future work items. We discuss potential roadmaps for thefuture standardisation of this developing industry, and the likely challenges to be encounteredalong the way.

  • 179.
    Wernersson Brodin, F.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Weiby Gregersen, Ø
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose nanofibrils: Challenges and possibilities as a paper additive or coating material – A review2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 1, no 29, p. 156-166Article in journal (Refereed)
  • 180.
    Wetterskog, E
    et al.
    Uppsala University, Sweden.
    Castro, A
    SOLVE Research and Consultancy AB, Sweden.
    Zeng, L
    Chalmers University of Technology, Sweden .
    Petronis, Sarunas
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Heinke, D
    nanoPET Pharma GmbH, Germany.
    Olsson, E
    Chalmers University of Technology, Sweden .
    Nilsson, L
    Lund University, Sweden; SOLVE Research and Consultancy AB, Sweden.
    Gehrke, N
    nanoPET Pharma GmbH, Germany.
    Svedlindh, P
    Uppsala University, Sweden.
    Size and property bimodality in magnetic nanoparticle dispersions: single domain particles vs. strongly coupled nanoclusters2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 12, p. 4227-4235Article in journal (Refereed)
    Abstract [en]

    The widespread use of magnetic nanoparticles in the biotechnical sector puts new demands on fast and quantitative characterization techniques for nanoparticle dispersions. In this work, we report the use of asymmetric flow field-flow fractionation (AF4) and ferromagnetic resonance (FMR) to study the properties of a commercial magnetic nanoparticle dispersion. We demonstrate the effectiveness of both techniques when subjected to a dispersion with a bimodal size/magnetic property distribution: i.e., a small superparamagnetic fraction, and a larger blocked fraction of strongly coupled colloidal nanoclusters. We show that the oriented attachment of primary nanocrystals into colloidal nanoclusters drastically alters their static, dynamic, and magnetic resonance properties. Finally, we show how the FMR spectra are influenced by dynamical effects; agglomeration of the superparamagnetic fraction leads to reversible line-broadening; rotational alignment of the suspended nanoclusters results in shape-dependent resonance shifts. The AF4 and FMR measurements described herein are fast and simple, and therefore suitable for quality control procedures in commercial production of magnetic nanoparticles.

  • 181. Wågberg, L.
    et al.
    Decher, G.
    Norgren, M.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Ankerfors, Mikael
    RISE, STFI-Packforsk.
    Axnäs, K.
    The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 3, p. 784-795Article in journal (Refereed)
    Abstract [en]

    A new type of nanocellulosic material has been prepared by high-pressure homogenization of carboxymethylated cellulose fibers followed by ultrasonication and centrifugation. This material had a cylindrical cross-section as shown by transmission electron microscopy with a diameter of 5-15 nm and a length of up to 1 ÎŒm. Calculations, using the Poisson-Boltzmann equation, showed that the surface potential was between 200 and 250 mV, depending on the pH, the salt concentration, and the size of the fibrils. They also showed that the carboxyl groups on the surface of the nanofibrils are not fully dissociated until the pH has reached pH = ∌10 in deionized water. Calculations of the interaction between the fibrils using the Derjaguin-Landau-Verwey-Overbeek theory and assuming a cylindrical geometry indicated that there is a large electrostatic repulsion between these fibrils, provided the carboxyl groups are dissociated. If the pH is too low and/or the salt concentration is too high, there will be a large attraction between the fibrils, leading to a rapid aggregation of the fibrils. It is also possible to form polyelectrolyte multilayers (PEMs) by combining different types of polyelectrolytes and microfibrillated cellulose (MFC). In this study, silicon oxide surfaces were first treated with cationic polyelectrolytes before the surfaces were exposed to MFC. The build-up of the layers was monitored with ellipsometry, and they show that it is possible to form very well-defined layers by combinations of MFC and different types of polyelectrolytes and different ionic strengths of the solutions during the adsorption of the polyelectrolyte. A polyelectrolyte with a three-dimensional structure leads to the build-up of thick layers of MFC, whereas the use of a highly charged linear polyelectrolyte leads to the formation of thinner layers of MFC. An increase in the salt concentration during the adsorption of the polyelectrolyte results in the formation of thicker layers of MFC, indicating that the structure of the adsorbed polyelectrolyte has a large influence on the formation of the MFC layer. The films of polyelectrolytes and MFC were so smooth and well-defined that they showed clearly different interference colors, depending on the film thickness. A comparison between the thickness of the films, as measured with ellipsometry, and the thickness estimated from their colors showed good agreement, assuming that the films consisted mainly of solid cellulose with a refractive index of 1.53. Carboxymethylated MFC is thus a new type of nanomaterial that can be combined with oppositely charged polyelectrolytes to form well-defined layers that may be used to form, for example, new types of sensor materials.

  • 182. Xhanari, K.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Paso, K.
    Stenius, P.
    Reduction of water wettability of nanofibrillated cellulose by adsorption of cationic surfactants2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18Article in journal (Refereed)
  • 183. Xhanari, K.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Paso, K.
    Stenius, P.
    Structure of nanofibrillated cellulose layers at the o/w interface2011In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 356Article in journal (Refereed)
  • 184. Xhanari, K.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Stenius, P.
    Emulsions stabilized by microfibrillated cellulose: The effect of hydrofobization, concentration and o/w-ratio2011In: Journal of Dispersion Science and Technology, ISSN 0193-2691, E-ISSN 1532-2351, Vol. 32Article in journal (Refereed)
  • 185.
    Zhao, Yadong
    et al.
    KTH Royal Institute of Technology, Sweden.
    Moser, Carl
    KTH Royal Institute of Technology, Sweden ; Valmet AB, Sweden.
    Lindström, Mikael E.
    KTH Royal Institute of Technology, Sweden.
    Henriksson, Gunnar
    KTH Royal Institute of Technology, Sweden.
    Li, Jiebing
    RISE - Research Institutes of Sweden, Bioeconomy. KTH Royal Institute of Technology, Sweden.
    Cellulose Nanofibers from Softwood, Hardwood, and Tunicate: Preparation-Structure-Film Performance Interrelation2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 15, p. 13508-13519Article in journal (Refereed)
    Abstract [en]

    This work reveals the structural variations of cellulose nanofibers (CNF) prepared from different cellulose sources, including softwood (Picea abies), hardwood (Eucalyptus grandis × E. urophylla), and tunicate (Ciona intestinalis), using different preparation processes and their correlations to the formation and performance of the films prepared from the CNF. Here, the CNF are prepared from wood chemical pulps and tunicate isolated cellulose by an identical homogenization treatment subsequent to either an enzymatic hydrolysis or a 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. They show a large structural diversity in terms of chemical, morphological, and crystalline structure. Among others, the tunicate CNF consist of purer cellulose and have a degree of polymerization higher than that of wood CNF. Introduction of surface charges via the TEMPO-mediated oxidation is found to have significant impacts on the structure, morphology, optical, mechanical, thermal, and hydrophobic properties of the prepared films. For example, the film density is closely related to the charge density of the used CNF, and the tensile stress of the films is correlated to the crystallinity index of the CNF. In turn, the CNF structure is determined by the cellulose sources and the preparation processes. This study provides useful information and knowledge for understanding the importance of the raw material for the quality of CNF for various types of applications.

  • 186. Zhao, Yadong
    et al.
    Zhang, Yujia
    Lindström, Mikael E
    Li, Jiebing
    RISE, Innventia.
    High performance composite film prepared from glucomannan and tunicate cellulose nanocrystals2014Conference paper (Refereed)
  • 187.
    Zhao, Yichen
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sugunan, Abhilash
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Wang, Qin
    RISE, Swedish ICT, Acreo.
    Yang, Xuran
    KTH Royal Institute of Technology, Sweden.
    Rihtnesberg, David B.
    RISE, Swedish ICT, Acreo.
    Toprak, Muhammet S.
    KTH Royal Institute of Technology, Sweden.
    Direct Determination of Spatial Localization of Carriers in CdSe-CdS Quantum Dots2015In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2015, article id 321354Article in journal (Refereed)
    Abstract [en]

    Colloidal quantum dots (QDs) have gained significant attention due to their tunable band gap, simple solution processability, ease of scale-up, and low cost. By carefully choosing the materials, core-shell heterostructure QDs (HQDs) can be further synthesized with a controlled spatial spread of wave functions of the excited electrons and holes for various applications. Many investigations have been done to understand the exciton dynamics by optical characterizations. However, these spectroscopic data demonstrate that the spatial separation of the excitons cannot distinguish the distribution of excited electrons and holes. In this work, we report a simple and direct method to determine the localized holes and delocalized electrons in HQDs. The quasi-type-II CdSe-CdS core-shell QDs were synthesized via a thermolysis method. Poly(3-hexylthiophene) (P3HT) nanofiber and ZnO nanorods were selected as hole and electron conductor materials, respectively, and were combined with HQDs to form two different nanocomposites. Photoelectrical properties were evaluated under different environments via a quick and facile characterization method, confirming that the electrons in the HQDs were freely accessible at the surface of the nanocrystal, while the holes were confined within the CdSe core.

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  • 188. Zhou, Q.
    et al.
    Malm, E.
    Nilsson, Helena
    RISE, Innventia.
    Larsson, Per Tomas
    RISE, Innventia.
    Iversen, Tommy
    RISE, Innventia.
    Berglund, L. A.
    Bulone, V.
    Nanostructured biocomposites based on bacterial cellulosic nanofibers compartmentalized by a soft hydroxyethylcellulose matrix coating2009In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Soft Matter, Vol. 5, no 21, p. 4124-4130Article in journal (Refereed)
    Abstract [en]

    Biomimetic approaches involving environmentally-friendly synthetic pathways provide an opportunity to elaborate novel high-performance biocomposites. Here we have developed a low-energy biosynthetic system for the production of a high-strength composite material consisting of self-assembled and nanostructured cellulosic nanofibers. This biocomposite is analogous to natural composite materials with high strength and hierarchical organization such as wood or tendon. It was generated by growing the bacterium Acetobacter, which naturally produces cellulosic nanofibers, in the presence of hydroxyethylcellulose (HEC). Individual cellulose fibrils were coated by HEC and exhibited a smaller lateral dimension than pure bacterial cellulose (BC) fibrils. They self-assembled to form compartmentalized nanofibers and larger cellulose fibril aggregates compared to pure BC. The tensile strength of nanocomposite films prepared from the compartmentalized cellulosic nanofibers was 20% higher than that of pure BC sheets and wood cellulose nanopapers, and 60% higher than that of conventional BC/HEC blends, while no strain-to-failure decrease was observed. The thin nanoscale coating consisting of hydrated HEC significantly increased the mechanical performance of the nanocomposite films by provoking compartmentalization of individual fibrils.

  • 189. Zhu, H.
    et al.
    Helander, M.
    RISE, Innventia.
    Moser, C.
    Ståhlkranz, A.
    Söderberg, D.
    RISE, Innventia.
    Henriksson, G.
    Lindström, M.
    RISE, Innventia.
    A novel nano cellulose preparation method and size fraction by cross flow ultra- filtration2012In: Current organic chemistry, ISSN 1385-2728, E-ISSN 1875-5348, no 16, p. 1871-1875Article in journal (Refereed)
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