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- Abitbol, Tiffany, et al.
(författare)
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Nanocellulose-Based Hybrid Materials for UV Blocking and Mechanically Robust Barriers
- 2020
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Ingår i: ACS Applied Bio Materials. - : American Chemical Society (ACS). - 2576-6422. ; 3:4, s. 2245-2254
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose (NC)-based hybrid coatings and films containing CeO2 and SiO2 nanoparticles (NPs) to impart UV screening and hardness properties, respectively, were prepared by solvent casting. The NC film-forming component (75 wt % of the overall solids) was composed entirely of cellulose nanocrystals (CNCs) or of CNCs combined with cellulose nanofibrils (CNFs). Zeta potential measurements indicated that the four NP types (CNC, CNF, CeO2, and SiO2) were stably dispersed in water and negatively charged at pH values between 6 and 9. The combination of NPs within this pH range ensured uniform formulations and homogeneous coatings and films, which blocked UV light, the extent of which depended on film thickness and CeO2 NP content, while maintaining good transparency in the visible spectrum (∼80%). The addition of a low amount of CNFs (1%) reduced the film hardness, but this effect was compensated by the addition of SiO2 NPs. Chiral nematic self-assembly was observed in the mixed NC film; however, this ordering was disrupted by the addition of the oxide NPs. The roughness of the hybrid coatings was reduced by the inclusion of oxide NPs into the NC matrix perhaps because the spherical oxide NPs were able to pack into the spaces between cellulose fibrils. We envision these hybrid coatings and films in barrier applications, photovoltaics, cosmetic formulations, such as sunscreens, and for the care and maintenance of wood and glass surfaces, or other surfaces that require a smooth, hard, and transparent finish and protection from UV damage.
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| 5. |
- Brandner, Birgit D., et al.
(författare)
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Solvent segregation and capillary evaporation at a superhydrophobic surface investigated by confocal Raman microscopy and force measurements
- 2011
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Ingår i: SOFT MATTER. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 7:3, s. 1045-1052
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Tidskriftsartikel (refereegranskat)abstract
- Wetting of water, a 1 : 1 water/ethanol mixture and an aqueous dodecylbenzene sulfonic acid surfactant solution on hydrophobic and superhydrophobic surfaces were studied using confocal Raman microscopy. The superhydrophobic surfaces were prepared by immersion of a glass substrate in a silica particle/fluoropolymer formulation followed by silanization. Preparation of hydrophobic surfaces was done in the same way with the exception that the silica particles were excluded from the formulation. The hydrophobic and superhydrophobic surfaces were characterized with respect to surface roughness using AFM, and by contact angle measurements using different liquids. Confocal Raman microscopy measurements in a 1 : 1 water/ethanol mixture showed an enrichment of ethanol close to the superhydrophobic surface, which could not be observed for the hydrophobic surface. Unexpectedly, the Raman spectrum of a pure water film in close proximity to the superhydrophobic surface displayed some differences compared to that of bulk water and indicated a stronger hydrogen-bonding close to the superhydrophobic surface. Evidence for capillary evaporation next to the superhydrophobic surface was also found, and this results in very long-range capillary attraction between one superhydrophobic surface and a hydrophobic colloidal probe as shown by AFM colloidal probe force measurements. Addition of a surfactant or ethanol suppresses capillary evaporation.
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| 8. |
- Charlène, Reverdy, et al.
(författare)
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Superhydrophobic surfaces manufacturing with nanocellulose
- 2016
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Ingår i: N.I.C.E. 2016 - The 3rd International Conference on Bioinspired and Biobased Chemistry & Materials.
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Konferensbidrag (refereegranskat)abstract
- Researchers in natural fibers see opportunities in superhydrophobicity for fabrics or paper. The first challenge with natural fiber is their high hydrophilicity when the second is the perpetual search for water born coating in papermaking. These challenges were overcome by a one pot formulation comprising a latex binder, precipitated calcium carbonate and fatty acids to give their hydrophobicity to pigments 1. In this study, we want to go further by replacing the petro-sourced latex with a new kind of fibers that are cellulose nanofibers (CNF).Inspired by the Lotus leaf, superhydrophobic surfaces have been a center of interest in the last decade because of their high potential in industry for a variety of applications. It is seen as the next generation of surface for anti-fouling and corrosive retardant in navy industry but also in general anti corrosive materials industry. Now widely studied , mechanisms for manufacturing superhydrophobicity are well understood. Born from the alliance of low surface energy chemistry and physical structuration of surface, superhydrophobic materials give a water contact angle above 150° and a slidding angle below 10°.
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| 9. |
- Chernyy, Sergey, et al.
(författare)
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Superhydrophilic Polyelectrolyte Brush Layers with Imparted Anti-Icing Properties : Effect of Counter ions
- 2014
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:9, s. 6487-6496
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Tidskriftsartikel (refereegranskat)abstract
- 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 degrees C and 70% at 10 degrees C. Ag+ ions reduce ice adhesion by 80% at -10 degrees C relative to unmodified glass. In general, superhydrophilic polyelectrolyte brushes exhibit better anti-icing property at -10 degrees 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.
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| 10. |
- Ejenstam, Lina, 1985-, et al.
(författare)
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Corrosion protection by hydrophobic silica particle-polydimethylsiloxane composite coatings
- 2015
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Ingår i: Corrosion Science. - : Elsevier. - 0010-938X .- 1879-0496. ; 99, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the time-dependent corrosion protection ability of 10-15. μm thin polydimethylsiloxane-nanoparticle composite coatings was evaluated using mainly open circuit potential and electrochemical impedance spectroscopy measurements. The best result was obtained for the coating containing 20. wt% hydrophobic silica nanoparticles, where it was possible to achieve protection for almost 80 days in 3. wt% NaCl solution. The protective properties offered by this coating are suggested to be due to a synergistic effect of the hydrophobicity of the polydimethylsiloxane matrix and the prolonged diffusion path caused by addition of hydrophobic silica particles.
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