Superhydrophobic polymeric coatings produced by rapid expansion of supercritical solutions combined with electrostatic deposition (RESS-ED)

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. (C) 2014 The Authors. Published by Elsevier B.V.