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- Ovaskainen, Louise, et al.
(författare)
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Superhydrophobic polymeric coatings produced by rapid expansion of supercritical solutions combined with electrostatic depostion (RESS-ED)
- 2014
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 95, s. 610-617
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a method to produce superhydrophobic polymeric coatings by combining the rapid expansion of supercritical solutions (RESS) with electrostatic deposition (ED). A copolymer, poly(vinyl acetate)-poly(vinyl pivalate) was dissolved in a mixture of supercritical carbon dioxide and acetone and sprayed through a nozzle with an applied voltage of 8 kV onto a surface placed on a earthed collector. Spray distance and polymer concentration were altered to find the most suitable spraying conditions. Superhydrophobic surfaces were produced when spraying both with and without a voltage, although the water repellent surfaces could be produced at a larger variety of processing parameters using the RESS-ED technique. The greatest improvement of using the RESS-ED process was that larger and thinner coatings were produced with a more even surface coverage of the created polymer particles compared to spraying without the applied voltage.
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| 2. |
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| 3. |
- Ovaskainen, Louise, et al.
(författare)
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Towards superhydrophobic coatings made by non-fluorinated polymers sprayed from a supercritical solution
- 2013
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 77, s. 134-141
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to create a superhydrophobic surface using polymers that are non-fluorinated and applying them to a surface via rapid expansion of a supercritical solution (RESS). Solubility studies of poly(epsilon-caprolactone) (PCL) and a statistical copolymer of vinyl acetate and vinyl pivalate (P(VAc-VPi))in supercritical carbon dioxide (scCO(2)) were carried out using an extraction procedure. It was found that the most suitable process parameters for spraying these polymers using the RESS technique were 30 MPa, 40 degrees C and 10% (v/v) acetone as a co-solvent. The surfaces produced were characterized in terms of their morphology and hydrophobic properties by scanning electron microscopy and contact angle measurements, respectively. The most hydrophobic surfaces were obtained by spraying the P(VAc-VPi) copolymers, giving advancing water contact angles in the range of 120-155 degrees due to the hydrophobic character of the polymer and the microstructure formed with the RESS technique. These results show great promise for the creation of superhydrophobic surfaces using non-fluorinated polymers applied to surfaces via RESS technique.
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| 4. |
- Sagnelli, Domenico, et al.
(författare)
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Green enzymatic synthesis and processing of poly (cis-9,10-epoxy-18-hydroxyoctadecanoic acid) in supercritical carbon dioxide (scCO(2))
- 2021
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 161, s. 110827-
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Tidskriftsartikel (refereegranskat)abstract
- There is significant potential for industrial use of renewables for a wide range of materials demanded by society. Plants, trees and algae are increasingly attracting attention as sustainable sources for functionalised and polymerizable building blocks. In particular, the outer bark of the birch tree (Betula pendula) is a side stream of the forestry industry with so far very little utilisation besides energy recovery. It is composed of a macromolecular network, suberin, that could provide a renewable, low cost and competitive resource. Within raw suberin is the potentially very useful multifunctional extract cis-9,10-epoxy-18-hydroxyoctadecanoic acid (CHA). Our drive has been to develop a green and sustainable synthetic strategy to CHA-based polyesters, by exploiting supercritical carbon dioxide (scCO2) as a reaction medium and leveraging the regio- and chemo-selective properties of the biocatalyst Novozym 435 (Lipase B). Low temperature (35-55 degrees C) polycondensation in scCO2 shows significant advantages compared to traditional polymerisation methods leading to reasonably high molecular weight polyesters. The mild synthetic conditions also preserve the valuable epoxy groups of the CHA which we show can be exploited by post-polymerisation functionalisation to create sustainable resins for bio-renewable coatings.
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