Effect of Silica Size and Content on Superamphiphobic Properties of Silica-Fluoropolymer Core-Shell Coatings

We present a facile approach to fabricate superamphiphobic surfaces by spray coating silica-fluoropolymer core-shell particles without substrate pretreatment with an additional binder resin. A series of SiO(2)@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate) (SiO(2)@PFMA) core-shell particles with core particles of different sizes were prepared via thiol-lactam initiated radical polymerization (TLIRP). The surface of each SiO(2) particle with an average particle size of 12, 80, 150, and 350 nm was modified with (3-mercaptopropyl) trimethoxysilane and used as a seed for TLIRP. The SiO(2)@PFMA particles with various SiO(2) sizes and contents were coated on aluminum substrates by a spray gun and then thermally treated to form a stable, rough composite layer. During the spray coating, the core-shell particles were aggregated by rapid evaporation of the solvent and then irregularly adhered to the substrate resulting in hierarchical structures. In the case of SiO(2)@PFMAs with low SiO(2) contents, the roughness created mainly by the polymer shell disappeared during heat treatment. However, the substrates coated with SiO(2)@PFMAs with high SiO(2) contents maintained the roughness even after heat treatment. The core-shell particles prepared with 12 nm SiO(2) formed a stable superamphiphobic surface. The water/hexadecane contact and sliding angles on an aluminum plate coated with SiO(2)@PFMA, prepared using 12 nm silica at 46 wt% silica content (12 nm-SiO(2)(46)@PFMA), were 178.5°/159.2° and 1°/7°, respectively. The cross-cut tape test showed that adhesion between the 12nm-SiO(2)(46)@PFMA and the aluminum substrate was classified as 5B. A glass surface spray-coated with the core-shell composite particles exhibited transparent superhydrophobicity and translucent superamphiphobicity by controlling the concentration of the coating solution.