Effects of modification of palygorskite on superamphiphobicity and microstructure of palygorskite@fluorinated polysiloxane superamphiphobic coatings

Abstract Palygorskite (PAL) is a promising natural clay mineral for the preparation of bionic super anti-wetting coatings, a new application field of PAL. Here, the effects of modification of PAL on superamphiphobicity and microstructure of the PAL@fluorinated polysiloxane (PAL@fluoroPOS) superamphiphobic coatings were systematically studied. First, PAL was modified via acid activation, solid-state grinding and heat activation. Then, the PAL@fluoroPOS coatings were prepared by hydrolytic condensation of 1H,1H,2H,2H-perfluorodecyltriethoxysilane and tetraethoxysilane onto the modified PAL, followed by spay-coating onto substrates. It was found that the microstructure of the coatings is controllable by acid activation and solid-state grinding. Acid activation with HCl at moderate conditions (2 M HCl, 15 °C) and grinding for a proper time (10 min) are helpful to improve superamphiphobicity of the coatings by forming smaller protrusions and micropores on the surface of the coatings. On the contrary, heat activation results in decline of the superamphiphobicity, especially at high temperature. The achieved coatings show excellent superamphiphobicity, and are mechanically robust and thermally stable, which can withstand intensive water jetting at 100 kPa for 20 min and 350 °C for 1 h. Moreover, the coatings can be applied onto various substrates like aluminum foil, PTFE plate, wood plate and polyester textile. We believe that the findings will promote the development of novel clay-based super anti-wetting coatings.