Fluorinated Raspberry-Like Particles for Superamphiphobic Coatings

Abstract

Raspberry-like polystyrene particles were fabricated through the covalent linkage of small epoxy-functionalized polystyrene particles (PS-GMA) with large amino-functionalized polystyrene particles (PS-NH2). These covalent bonds yielded more stable and robust particle clusters than would be anticipated from non-covalent interactions. While the structures of these raspberry-like particles provided them with a dual-scale hierarchical roughness and re-entrant sites, they were further functionalized with a fluorinated random copolymer to provide them a low surface tension. The fluorinated random copolymer used to functionalize these raspberry-like particles was poly(glycidyl methacrylate20%)-co-2(perfluorooctyl)ethyl methacrylate80%)25 or P(GMA20%-co-FOEMA80%)25, where the subscript 25 denotes the total number of the respective GMA and FOEMA units, while the subscript 20% and 80% denote the molar fractions of GMA and FOEMA, respectively. The epoxy groups of the GMA units could react with the amino groups of the raspberry-like particles, thus incorporating the fluorinated polymer onto the surfaces of the raspberry-like particles. In addition, the FOEMA component provided the particles with enhanced amphiphobicity. Subsequently, these fluorinated raspberry-like particles were cast onto glass slides to demonstrate their superamphiphobic properties. These coatings exhibited superhydrophobic behavior when they were tested against water droplets. Additionally, the oil-repellency of these coatings was tested against various liquids, including diiodomethane, cooking oil, and hexadecane. The coatings exhibited superoleophobic behavior against diiodomethane and cooking oil, as well as highly oleophobic behavior against hexadecane. This work demonstrates a simple and efficient route for the fabrication of superamphiphobic surfaces. Additionally, these surfaces are among the first examples of coatings prepared via self-assembly techniques that exhibited high repellency against hexadecane. These materials could have potential in various applications that require protection of a surface against wetting by either water or oils.