Preparation of highly hydrophobic and oleophobic textile surfaces using microwave-promoted silane coupling

The wetting behavior of a solid surface is controlled by the geometric structure as well as the chemical composition of the material. In this study, highly hydrophobic and oleophobic materials were prepared by microwave-assisted cross-linking of perfluoroalkoxysilane onto nylon and cotton-blended fabric. Surface roughness was controlled by choice of the catalyst. Water catalysis resulted in a smooth coating deposition of the perfluoroalkoxysilanes on the fiber surface, while base catalysis resulted in a micro and nano scale rough surface on the fibers. Both water and base-catalyzed materials were superhydrophobic, but creating multi-scale geometric structure via base catalysis was required to improve oleophobicity. A series of experiments explored the parameters of fluorosilane concentration, base catalysis, curing time, and the number of cures. The apparent contact angles of the fabric samples treated in a multiple dip-and-cure sequence averaged 135° (hexadecane) and 148° (water) with no absorption of either within 60 h (hexadecane) or until complete evaporation (water).