Bi-functional random copolymers for one-pot fabrication of superamphiphobic particulate coatings

Random bi-functional copolymers bearing fluorinated units and sol-gel forming units were prepared and used together with silica particles in a one-pot process for preparing superamphiphobic coatings. The copolymers P(FOEA-r-IPSMA) were prepared by atom transfer radical polymerization (ATRP) of 2-(perfluorooctyl) ethyl acrylate (FOEA) and 3-(triisopropyloxy)silylpropyl methacrylate (IPSMA). The uniform silica particles were prepared using a modified Stober process. Stirring P(FOEA-r-IPSMA), silica, water, and HCl together with substrates triggered the sol-gel reactions of the IPSMA units. These involved first the hydrolysis of IPSMA to yield silanol groups and then the condensation of the IPSMA silanol groups among themselves, and with silanol groups on silica or glass surfaces or with hydroxyl groups on cotton or filter paper. At optimized mass ratios of P(FOEA-r-IPSMA) to silica, the resultant coatings consisted of lightly covered silica particles that were embedded in a crosslinked P(FOEA-r-IPSMA) film. By optimizing the molar ratio between FOEA and IPSMA in P(FOEA-r-IPSMA), the rough particulate coatings on cotton, filter paper, and glass plates exhibited superamphiphobicity. More importantly, the particulate coatings were resistant to solvent extraction and NaOH etching.