Fabrication of superhydrophobic and highly oleophobic silicon-based surfaces via electroless etching method

摘要

This study reports on a simple method for the preparation of superhydrophobic and highly oleophobic nanostructured silicon surfaces. The technique relies on metal-assisted electroless etching of silicon in sodium tetrafluoroborate (NaBF_4) aqueous solution. Then, silver particles were deposited on the obtained surfaces, changing their overall physical morphology. Finally, the surfaces were coated by either C_4F_8, a fluoropolymer deposited by plasma, or by SiO_x overlayers chemically modified with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFTS) through silanization reaction. All these surfaces exhibit a superhydrophobic character (large apparent contact angle and low hysteresis with respect to water). In addition, they present high oleophobic properties, i.e. a high repellency to low surface energy liquids with various contact angle hysteresis, both depending on the morphology and type of coating.