Reducing the contact angle hysteresis of thin polymer films by oil impregnation in supercritical carbon dioxide

In the present work, a novel one-stage approach to the creation of omniphobic surface using supercritical carbon dioxide as a solvent is proposed. Poly(perfluorohexyl ethyl methacrylate - hydroxypropyl methacrylate) copolymer cross-linked with hexamethylene diisocyanate is used as a polymer matrix, and polyoxaperfluorobutyl bromide (oil) is used as a lubricant. Oil content in the obtained films is measured by thermogravimetry and compared with the classical Flory-Rehner theory. It is shown that the addition of fluorinated oil to the synthesis process results in a significant decrease of apparent contact angle hysteresis and sliding angles of the obtained gel thin films. The proposed technique may be of interest for SLIPS application on surfaces with a complex structure like fabrics.