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  • 1.
    Aulin, C.
    et al.
    RISE, Innventia.
    Karabulut, E.
    Tran, A.
    Waisgberg, L.
    Lindström, T.
    RISE, Innventia.
    Transparent nanocellulosic multilayer thin films on polylactic acid with tunable gas barrier properties2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, no 15, p. 7352-7359Article in journal (Refereed)
  • 2. Aulin, C.
    et al.
    Yun, S. H.
    Wåberg, L.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Design of highly oleophobic cellulose surfaces from structured silicon templates2009In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 1, no 11, p. 2443-2452Article in journal (Refereed)
    Abstract [en]

    Structured silicon surfaces, possessing hierarchical porous characteristics consisting of micrometer-sized cavities superimposed upon a network of nanometer-sized pillars or wires, have been fabricated by a plasma-etching process. These surfaces have superoleophobic properties, after being coated with fluorinated organic trichlorosilanes, on intrinsically oleophilic surfaces. By comparison with flat silicon surfaces, which are oleophilic, it has been demonstrated that a combination of low surface energy and the structured features of the plasma-etched surface is essential to prevent oil from penetrating the surface cavities and thus induce the observed macroscopic superoleophobic phenomena with very low contact-angle hysteresis and low roll-off angles. The structured silicon surfaces were coated with cellulose nanocrystals using the polyelectrolyte multilayer technique. The cellulose surfaces prepared in this way were then coated with a monolayer of fluorinated trichlorosilanes. These porous cellulose films displayed highly nonwetting properties against a number of liquids with low surface tension, including alkanes such as hexadecane and decane. The wettability and chemical composition of the cellulose/silicon surfaces were characterized with contact-angle goniometry and X-ray photoelectron spectroscopy, respectively. The nano/microtexture features of the cellulose/silicon surfaces were also studied with field-emission scanning electron microscopy. The highly oleophobic structured cellulose surfaces are very interesting model surfaces for the development of biomimetic self-cleaning surfaces in a vast array of products, including green constructions, packaging materials, protection against environmental fouling, sports, and outdoor clothing, and microfluidic systems.

  • 3.
    Boge, Lukas
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation. Chalmers University of Technology, Sweden.
    Browning, Kathryn
    University of Copenhagen, Denmark.
    Nordström, Randi
    Uppsala University, Sweden.
    Campana, Mario
    Rutherford Appleton Laboratory, UK.
    Damgaard, Liv
    University of Copenhagen, Denmark.
    Seth Caous, Josefin
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Hellsing, Maja
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Ringstad, Lovisa
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Andersson, Martin
    Chalmers University of Technology, Sweden.
    Peptide-Loaded Cubosomes Functioning as an Antimicrobial Unit against Escherichia coli2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 24, p. 21314-21322Article in journal (Refereed)
    Abstract [en]

    Dispersions of cubic liquid crystalline phases, also known as cubosomes, have shown great promise as delivery vehicles for a wide range of medicines. Due to their ordered structure, comprising alternating hydrophilic and hydrophobic domains, cubosomes possess unique delivery properties and compatibility with both water-soluble and -insoluble drugs. However, the drug delivery mechanism and cubosome interaction with human cells and bacteria are still poorly understood. Herein, we reveal how cubosomes loaded with the human cathelicidin antimicrobial peptide LL-37, a system with high bacteria-killing effect, interact with the bacterial membrane and provide new insights into the eradication mechanism. Combining the advanced experimental techniques neutron reflectivity and quartz crystal microbalance with dissipation monitoring, a mechanistic drug delivery model for LL-37-loaded cubosomes on bacterial mimicking bilayers was constructed. Moreover, the cubosome interaction with Escherichia coli was directly visualized using super-resolution laser scanning microscopy and cryogenic electron tomography. We could conclude that cubosomes loaded with LL-37 adsorbed and distorted bacterial membranes, providing evidence that the peptide-loaded cubosomes function as an antimicrobial unit.

  • 4.
    Bridarolli, Alexandra
    et al.
    UCL Eastman Dental Institute, United Kingdom.
    Odlyha, Marianne
    Birkbeck College, United Kingdom.
    Nechyporchuk, Oleksandr
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Holmberg, Krister
    Chalmers University of Technology, Sweden.
    Ruiz-Recasens, Cristina
    University of Barcelona, Spain.
    Bordes, Romain
    Chalmers University of Technology, Sweden.
    Bozec, L.
    UCL Eastman Dental Institute, United Kingdom; University of Toronto, Canada.
    Evaluation of the Adhesion and Performance of Natural Consolidants for Cotton Canvas Conservation2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 39, p. 33652-33661Article in journal (Refereed)
    Abstract [en]

    Recent developments in paper and canvas conservation have seen the introduction of nanocellulose (NC) as a compatible treatment for the consolidation of historical cellulosic artifacts and manuscripts. However, as part of the assessment of these new materials for canvas consolidation, the adhesion of the consolidation treatment (which takes place between the applied material and the substrate) has not yet been evaluated, and as a result, it is poorly understood by both the scientific and conservation communities. After evaluating the potential of NC treatments for the consolidation of cotton painting canvas, we investigate a route to promote the interaction between the existing canvas and the nanocellulose treatment, which is in our case made of cellulose nanofibrils (CNF). This was carried out by introducing a cationic polymer, polyamidoamine-epichlorohydrin (PAAE), as an intermediate layer between the canvas and the CNF. The morphological, chemical, and mechanical evaluation of the canvas samples at different relative humidity (RH) levels demonstrated how the adhesion of the added PAAE layer is a dominant factor in the consolidation process. Improvement in the coating of canvas single fibers by the CNF, higher adhesion energy between the canvas fibers and the CNF treatment, and finally overall stronger canvas reinforcement were observed following the introduction of PAAE. However, an increase in mechanical response to moisture sorption and desorption was also observed for the PAAE-treated canvases. Overall, this study shows the complexity of such systems and, as such, the relevance of using a multiscale approach for their assessment.

  • 5.
    Claesson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Nanoscale electrical and mechanical characteristics of conductive polyaniline network in polymer composite films2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, p. 19168-19175Article in journal (Refereed)
  • 6. de Oliveira, R
    et al.
    Sjödin, N
    Fokine, M
    Margulis, W
    RISE, Swedish ICT, Acreo.
    de Matos, C
    Norin, L
    RISE, Swedish ICT, Acreo.
    Fabrication Optical Characterization of Silica Optical Fibers Containing Gold Nanoparticles2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 1, p. 370-Article in journal (Refereed)
  • 7. Hansson, Susanne
    et al.
    Östmark, Emma
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Carlmark, A
    Malmström, Eva
    ARGET ATRP for versatile grafting of cellulose using various monomers2009In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 1, no 11, p. 2651-2659Article in journal (Refereed)
    Abstract [en]

    In recent years, cellulose-based materials have attracted significant attention. To broaden the application areas for cellulose, polymers are often grafted to/from the surface to modify its properties. This study applies ARGET (activators regenerated by electron transfer) ATRP (atom transfer radical polymerization) when straightforwardly grafting methyl methacrylate (MMA), styrene (St), and glycidyl methacrylate (GMA) from cellulose in the form of conventional filter paper in the presence of a sacrificial initiator. The free polymer, formed from the free initiator in parallel to the grafting, was characterized by 1H NMR and SEC, showing that sufficient control is achieved. However, the analyses also indicated that the propagation from the surface cannot be neglected compared to the propagation of the free polymer at higher targeted molecular weights, which is an assumption often made. The grafted filter papers were evaluated with FT-IR, suggesting that the amount of polymer on the surface increased with increasing monomer conversion, which the FE-SEM micrographs of the substrates also demonstrated. Water contact angle (CA) measurements implied that covering layers of PMMA and PS were formed on the cellulose substrate, making the surface hydrophobic, in spite of low DPs. The CA of the PGMA-grafted filter papers revealed that, by utilizing either aprotic or protic solvents when washing the substrates, it was possible to either preserve or hydrolyze the epoxy groups. Independent of the solvent used, all grafted filter papers were essentially colorless after the washing procedure because of the low amount of copper required when performing ARGET ATRP. Nevertheless, surface modification of cellulose via ARGET ATRP truly facilitates the manufacturing since no thorough freeze-thaw degassing procedures are required.

  • 8.
    Jacques, Eric
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lindbergh, Göran
    KTH Royal Institute of Technology, Sweden.
    Zenkert, Dan
    KTH Royal Institute of Technology, Sweden.
    Leijonmarck, Simon
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP.
    Hellqvist Kjell, Maria
    KTH Royal Institute of Technology, Sweden.
    Piezo-Electrochemical Energy Harvesting with Lithium-Intercalating Carbon Fibers2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 25, p. 13898-13904Article in journal (Refereed)
    Abstract [en]

    (Figure Presented) The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.

  • 9. Jafarzadeh, Shadi
    et al.
    Thormann, Esben
    Ronnevall, Ted
    Adhikari, Arindam
    Sundell, Per-Erik
    Pan, Jinshan
    Claesson, Per M
    YKI – Ytkemiska institutet.
    Toward homogeneous nanostructured polyaniline/resin blends2011In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 3, no 5, p. 1681-1691Article in journal (Refereed)
    Abstract [en]

    The high interest in applications of conducting polymers, especially polyaniline (PANI), makes it important to overcome limitations for effective usage due to poor processability and solubility. One promising approach is to make blends of PANT in polymeric resins. However, in this approach other problems related to the difficulty of achieving a homogeneous PANI dispersion arise. The present article is focused on this general problem, and we discuss how the synthesis method, choice of dopant and solvent as well as interfacial energies influence the dispersibility. For this purpose, different synthesis methods and dopants have been employed to prepare nanostructures of polyaniline. Dynamic light scattering analysis of dispersions of the synthesized particles in several solvents was employed in order to understand how the choice of solvent affects PANT aggregation. Further information on this subject was achieved by scanning electron microscopy studies of PANT powders dried from various solutions. On the basis of these results, acetone was found to be a suitable dispersion medium for PANI. The polymer matrix used to make the blends in this work is a UV-curing solvent-free resin. Therefore, there is no low molecular weight liquid in the system to facilitate the mixing process and promote formation of homogeneous dispersions. Thus, a good compatibility of the components becomes crucial. For this reason, surface tension and contact angle measurements were utilized for characterizing the surface energy of the PANI particles and the polyester acrylate (PEA) resin, and also for calculating the interfacial energy between these two components that revealed good compatibility within the PANI/PEA blend. A novel technique, based on centrifugal sedimentation analysis, was employed in order to determine the PANT particle size in PEA resin, and high dispersion stability of the PANI/PEA blends was suggested by evaluation of the sedimentation data.

  • 10.
    Järn, Mikael
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Swerin, Agne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Claesson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Superhydrophilic polyelectrolyte brush layers with imparted anti-icing properties: Effect of counter ions2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 9, p. 6487-6496Article in journal (Refereed)
    Abstract [en]

    This work demonstrates the feasibility of superhydrophilic polyelectrolyte brush coatings for anti-icing applications. Five different types of ionic and nonionic polymer brush coatings of 25-100 nm thickness were formed on glass substrates using silane chemistry for surface premodification followed by polymerization via the SI-ATRP route. The cationic [2-(methacryloyloxy)ethyl] trimethylammonium chloride] and the anionic [poly(3-sulfopropyl methacrylate), poly(sodium methacrylate)] polyelectrolyte brushes were further exchanged with H+, Li+, Na+, K+, Ag+, Ca2+, La3+, C16N+, F-, Cl-, BF4-, SO42-, and C12SO3- ions. By consecutive measurements of the strength of ice adhesion toward ion-incorporated polymer brushes on glass it was found that Li+ ions reduce ice adhesion by 40% at -18 °C and 70% at -10 °C. Ag+ ions reduce ice adhesion by 80% at -10 °C relative to unmodified glass. In general, superhydrophilic polyelectrolyte brushes exhibit better anti-icing property at -10 °C compared to partially hydrophobic brushes such as poly(methyl methacrylate) and surfactant exchanged polyelectrolyte brushes. The data are interpreted using the concept of a quasi liquid layer (QLL) that is enhanced in the presence of highly hydrated ions at the interface. It is suggested that the ability of ions to coordinate water is directly related to the efficiency of a given anti-icing coating based on the polyelectrolyte brush concept.

  • 11.
    Koppolu, R.
    et al.
    Åbo Akademi University, Finland.
    Lahti, J.
    Tampere University of Technology, Finland.
    Abitbol, Tiffany
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Swerin, Agne
    Kuusipalo, J.
    Tampere University of Technology, Finland.
    Toivakka, M.
    Åbo Akademi University, Finland.
    Continuous Processing of Nanocellulose and Polylactic Acid into Multilayer Barrier Coatings2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 12, p. 11920-11927Article in journal (Refereed)
    Abstract [en]

    Recent years have seen an increased interest toward utilizing biobased and biodegradable materials for barrier packaging applications. Most of the abovementioned materials usually have certain shortcomings that discourage their adoption as a preferred material of choice. Nanocellulose falls into such a category. It has excellent barrier against grease, mineral oils, and oxygen but poor tolerance against water vapor, which makes it unsuitable to be used at high humidity. In addition, nanocellulose suspensions' high viscosity and yield stress already at low solid content and poor adhesion to substrates create additional challenges for high-speed processing. Polylactic acid (PLA) is another potential candidate that has reasonably high tolerance against water vapor but rather a poor barrier against oxygen. The current work explores the possibility of combining both these materials into thin multilayer coatings onto a paperboard. A custom-built slot-die was used to coat either microfibrillated cellulose or cellulose nanocrystals onto a pigment-coated baseboard in a continuous process. These were subsequently coated with PLA using a pilot-scale extrusion coater. Low-density polyethylene was used as for reference extrusion coating. Cationic starch precoating and corona treatment improved the adhesion at nanocellulose/baseboard and nanocellulose/PLA interfaces, respectively. The water vapor transmission rate for nanocellulose + PLA coatings remained lower than that of the control PLA coating, even at a high relative humidity of 90% (38 °C). The multilayer coating had 98% lower oxygen transmission rate compared to just the PLA-coated baseboard, and the heptane vapor transmission rate reduced by 99% in comparison to the baseboard. The grease barrier for nanocellulose + PLA coatings increased 5-fold compared to nanocellulose alone and 2-fold compared to PLA alone. This approach of processing nanocellulose and PLA into multiple layers utilizing slot-die and extrusion coating in tandem has the potential to produce a barrier packaging paper that is both 100% biobased and biodegradable.

  • 12. Lonnberg, H.
    et al.
    Larsson, K.
    Lindström, T.
    RISE, Innventia.
    Hult, A.
    Malmström, E.
    Synthesis of polycaprolactone-grafted microfibrillated cellulose for use in novel bionanocomposites-influence of the graft length on the mechanical properties2011In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, no 5, p. 1426-1433Article in journal (Refereed)
  • 13.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Bordes, Romain
    Chalmers University of Technology, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wet Spinning of Flame-Retardant Cellulosic Fibers Supported by Interfacial Complexation of Cellulose Nanofibrils with Silica Nanoparticles2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 44, p. 39069-39077Article in journal (Refereed)
    Abstract [en]

    The inherent flammability of cellulosic fibers limits their use in some advanced applications. This work demonstrates for the first time the production of flame-retardant macroscopic fibers from wood-derived cellulose nanofibrils (CNF) and silica nanoparticles (SNP). The fibers are made by extrusion of aqueous suspensions of anionic CNF into a coagulation bath of cationic SNP at an acidic pH. As a result, the fibers with a CNF core and a SNP thin shell are produced through interfacial complexation. Silica-modified nanocellulose fibers with a diameter of ca. 15 μm, a titer of ca. 3 dtex and a tenacity of ca. 13 cN tex–1 are shown. The flame retardancy of the fibers is demonstrated, which is attributed to the capacity of SNP to promote char forming and heat insulation on the fiber surface.

  • 14.
    Nilebäck, Linnea
    et al.
    KTH Royal Institute of Technology, Sweden.
    Widhe, Mona
    KTH Royal Institute of Technology, Sweden.
    Seijsing, Johan
    Stockholm University, Sweden.
    Bysell, Helena
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Sharma, Prashant K
    University of Groningen, Netherlands; University Medical Center of Groningen, Netherlands.
    Hedhammar, My
    KTH Royal Institute of Technology, Sweden.
    Bioactive Silk Coatings Reduce the Adhesion of Staphylococcus aureus while Supporting Growth of Osteoblast-like Cells.2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252Article in journal (Refereed)
    Abstract [en]

    Orthopedic and dental implants are associated with a substantial risk of failure due to biomaterial-associated infections and poor osseointegration. To prevent such outcomes, a coating can be applied on the implant to ideally both reduce the risk of bacterial adhesion and support establishment of osteoblasts. We present a strategy to construct dual-functional silk coatings with such properties. Silk coatings were made from a recombinant partial spider silk protein either alone (silkwt) or fused with a cell-binding motif derived from fibronectin (FN-silk). The biofilm-dispersal enzyme Dispersin B (DspB) and two peptidoglycan degrading endolysins, PlySs2 and SAL-1, were produced recombinantly. A sortase recognition tag (SrtTag) was included to allow site-specific conjugation of each enzyme onto silkwt and FN-silk coatings using an engineered variant of the transpeptidase Sortase A (SrtA*). To evaluate bacterial adhesion on the samples, Staphylococcus aureus was incubated on the coatings and subsequently subjected to live/dead staining. Fluorescence microscopy revealed a reduced number of bacteria on all silk coatings containing enzymes. Moreover, the bacteria were mobile to a higher degree, indicating a negative influence on the bacterial adhesion. The capability to support mammalian cell interactions was assessed by cultivation of the osteosarcoma cell line U-2 OS on dual-functional surfaces, prepared by conjugating the enzymes onto FN-silk coatings. U-2 OS cells could adhere to silk coatings with enzymes and showed high spreading and viability, demonstrating good cell compatibility.

  • 15.
    Nordgren, N
    et al.
    YKI – Ytkemiska institutet.
    Lönnberg, H
    Hult, A
    Malmström, E
    Rutland, M
    YKI – Ytkemiska institutet.
    Adhesion dynamics for cellulose nano-composites2009In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 1, no 10, p. 2098–2103-Article in journal (Refereed)
    Abstract [en]

    The efficiency of poly(epsilon-caprolactone) (PCL) as a matrix polymer for cellulose nanocomposites has been investigated at the macromolecular contact level using atomic force microscopy in a colloidal probe configuration. Model cellulose microspheres grafted with PCL Were prepared via ring-opening polymerization. Force measurements between the functionalized particles revealed the adhesion to be highly dependent on the contact time because of a diffusion-controlled mechanism Moreover, an increase of the temperature to 60 degrees C (close to T-m for the PCL graft) greatly enhanced the adhesion at the polymer-polymer interface, demonstrating the importance of entanglements in the annealing of composite materials

  • 16.
    Nyström, Lina
    et al.
    Uppsala University, Sweden.
    Álvarez-Asencio, Rubén
    KTH Royal Institute of Technology, Sweden; IMDEA Nanoscience, Spain.
    Frenning, Göran
    Uppsala University, Sweden.
    Saunders, Brian R.
    University of Manchester, UK.
    Rutland, Mark W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    Malmsten, Martin
    Uppsala University, Sweden.
    Electrostatic swelling transitions in surface-bound microgels2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 40, p. 27129-27139Article in journal (Refereed)
    Abstract [en]

    Herein, electrostatic swelling transitions of poly(ethyl acrylate-co-methacrylic acid) microgels covalently bound to silica surfaces are investigated. Confined at a solid surface, microgel swelling is anisotropically hindered and the structure is flattened to an extent dictated by pH and microgel composition. Microgel deformation under applied load is also shown to depend on microgel charge density, with the highest deformation observed at intermediate charge densities. Two modes of microgel deformation under load were observed, one elastic and one viscoelastic, related to polymer strand deformation and displacement of trapped water, respectively. Results on polymer strand dynamics reveal that the microgels are highly dynamic, as the number of strand-tip interaction points increases 4-fold during a 10 s contact time. Furthermore, finite element modeling captures these effects qualitatively and shows that stress propagation in the microgel network decays locally at the rim of contact with a solid interface or close to the tip probe. Taken together, the results demonstrate a delicate interplay between the surface and microgel which determines the structure and nanomechanical properties of the latter and needs to be controlled in applications of systems such as pH-responsive surface coatings in biomaterials.

  • 17.
    Poxson, D. J.
    et al.
    Linköping University, Sweden.
    Gabrielsson, E. O.
    Linköping University, Sweden.
    Bonisoli, A.
    Linköping University, Sweden; Istituto Italiano di Tecnologia, Italy; Sant'Anna School of Advanced Studies, Italy.
    Linderhed, Ulrika
    RISE - Research Institutes of Sweden, ICT, Acreo. Linköping University, Sweden.
    Abrahamsson, T.
    Linköping University, Sweden.
    Matthiesen, I.
    Linköping University, Sweden; KTH Royal Institute of Technology, Sweden.
    Tybrandt, K.
    Linköping University, Sweden.
    Berggren, M.
    Linköping University, Sweden.
    Simon, D. T.
    Linköping University, Sweden.
    Capillary-Fiber Based Electrophoretic Delivery Device2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 15, p. 14200-14207Article in journal (Refereed)
    Abstract [en]

    Organic electronic ion pumps (OEIPs) are versatile tools for electrophoretic delivery of substances with high spatiotemporal resolution. To date, OEIPs and similar iontronic components have been fabricated using thin-film techniques and often rely on laborious, multistep photolithographic processes. OEIPs have been demonstrated in a variety of in vitro and in vivo settings for controlling biological systems, but the thin-film form factor and limited repertoire of polyelectrolyte materials and device fabrication techniques unnecessarily constrain the possibilities for miniaturization and extremely localized substance delivery, e.g., the greater range of pharmaceutical compounds, on the scale of a single cell. Here, we demonstrate an entirely new OEIP form factor based on capillary fibers that include hyperbranched polyglycerols (dPGs) as the selective electrophoretic membrane. The dPGs enable electrophoretic channels with a high concentration of fixed charges and well-controlled cross-linking and can be realized using a simple "one-pot" fluidic manufacturing protocol. Selective electrophoretic transport of cations and anions of various sizes is demonstrated, including "large" substances that are difficult to transport with other OEIP technologies. We present a method for tailoring and characterizing the electrophoretic channels' fixed charge concentration in the operational state. Subsequently, we compare the experimental performance of these capillary OEIPs to a computational model and explain unexpected features in the ionic current for the transport and delivery of larger, lower-mobility ionic compounds. From this model, we are able to elucidate several operational and design principles relevant to miniaturized electrophoretic drug delivery technologies in general. Overall, the compactness of the capillary OEIP enables electrophoretic delivery devices with probelike geometries, suitable for a variety of ionic compounds, paving the way for less-invasive implantation into biological systems and for healthcare applications.

  • 18. Sababi, M
    et al.
    Kettle, J
    Rautkoski, H
    Claesson, Per M
    YKI – Ytkemiska institutet.
    Thormann, E
    Structural and nanomechanical properties of paperboard coatings studied by peak force tapping atomic force microscopy2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 10, p. 5534-5541Article in journal (Refereed)
    Abstract [en]

    Paper coating formulations containing starch, latex, and clay were applied to paperboard and have been investigated by scanning electron microscopy and Peak Force tapping atomic force microscopy. A special focus has been on the measurement of the variation of the surface topography and surface material properties with a nanometer scaled spatial resolution. The effects of coating composition and drying conditions were investigated. It is concluded that the air-coating interface of the coating is dominated by close-packed latex particles embedded in a starch matrix and that the spatial distribution of the different components in the coating can be identified due to their variation in material properties. Drying the coating at an elevated temperature compared to room temperature changes the surface morphology and the surface material properties due to partial film formation of latex. However, it is evident that the chosen elevated drying temperature and exposure time is insufficient to ensure complete film formation of the latex which in an end application will be needed.

  • 19. Thormann, Esben
    et al.
    Yun, Sang Ho
    Claesson, Per M
    YKI – Ytkemiska institutet.
    Linnros, Jan
    Amontonian friction induced by flexible surface features on microstructured silicon2011In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 3, no 9, p. 3432-3439Article in journal (Refereed)
    Abstract [en]

    Friction between nonadhering sliding surfaces are normally described by Amontons' law, which states that there exists a linear relationship between the friction force and the normal applied load and that the friction force is independent of the macroscopic contact area between the surfaces and the sliding velocity. In this study we have measured friction as a function of applied load between a spherical silica particle and a microstructured silicon surface consisting of arrays of vertical microneedles, and we have challenged Amontons' law by changing the size of the silica particle and the sliding velocity. First, when looking at the friction as a function of time for a given applied load, the friction force was observed to oscillate with a period related to the spacing between the microneedles when using a small silica particle, whereas the friction force exhibited a more random variation when a larger silica particle was used. The oscillation in the friction force is a direct evidence for bending and release of individual microneedles and the observation illustrates that the energy dissipating mechanism becomes hidden in the friction data when the dimensions of the sliding body becomes much larger than the length scale of the surface features causing the friction. Second, when looking at the average friction force as a function of applied load we find, in accordance with Amontons' law, a linear relationship between the friction force and the applied load and the friction force is independent of both the size of the sliding silica particle and of the sliding velocity. One exception from this, however, was observed when sliding a small silica particle at low velocity, where a deviation from Amontons' law was noticed. The deviation from Amontons' law is suggested to be attributed to a change in the energy dissipating mechanism giving rise to the friction force. In light of that it is suggested that Amontons' law only is valid as long as the main energy dissipating mechanism does not change with the applied load. To get a better understanding of the general validity of Amontons' law, our results were evaluated against different microscopic models.

  • 20.
    Trey, Stacy
    et al.
    SP - Sveriges Tekniska Forskningsinstitut, SP Trä.
    Jafarzadeh, Shadi
    Johansson, Mats
    In situ Polymerization of Polyaniline in Wood Veneers2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 3, p. 1760–1769-Article in journal (Refereed)
  • 21.
    Trey, Stacy
    et al.
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Netrval, Julia
    Berglund, Lars
    Johansson, Mats
    Electron beam initiated polymerization of poly(ethylene glycol) based wood impregnants2010In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 2, no 11, p. 3352–3362-Article in journal (Refereed)
    Abstract [en]

    The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favourable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of Mw 550-575, of concentrations 0, 30, 60, and 100 wt% in water, were vacuum pressure impregnated into Scots Pine blocks of 15 x 25 x 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with non-irradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and un-cured vinyl PEG samples which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when placed in water was not observed to the same extent as PEG.

  • 22.
    Yang, Xuan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    Berglund, Lars
    KTH Royal Institute of Technology, Sweden.
    High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 10, p. 10310-10319Article in journal (Refereed)
    Abstract [en]

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

  • 23.
    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.

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