Development of superamphiphobic alumina nanofiber mats using trimethoxysilane with a short perfluoroalkyl chain

Abstract

To avoid the generation of hazardous, long-chain perfluoroalkyl carboxylic acids (CnF2n+1COOH, n ≥ 7), we develop relatively safer superamphiphobic alumina nanofiber mats. Our fabrication process focuses on two principles: lowering the surface energy using trimethoxy(1H, 1H, 2H, 2H-nonafluorohexyl)silane (C4F9CH2CH2Si(OCH3)3), which has short-chain perfluoroalkyls that are relatively safer than long-chain ones; and creating a high-roughness surface from electrospun alumina nanofibers with an average fiber diameter of 155 nm and inter-fiber spacing of 451 nm. Such mats exhibit super-repellency for water (contact angle θ* = 157°, contact angle hysteresis Δθ*=2∘, advancing angle θadv *= 158°, receding angle θrec *= 156°), and n-hexadecane (θ* = 151°, Δθ*=9°, θadv *= 152°, θrec *= 143°). Furthermore, superamphiphobicity is maintained up to 350℃.

Microwave‐Assisted Fabrication of Superamphiphobic Surfaces on Aluminum Substrates

“…It is already known from previous studies with Al and other substrates that the decomposition of the organic groups forming hydrophilic functional groups after cooling occurs at temperatures higher than 350-400 °C. [71][72][73][74] The temperature tests using lower surface tension liquids than water showed that the coatings retained the oleophobicity, losing the superoleophobic properties (Figure 7a). At 550 °C, the surface became superoleophilic.…”