Robust Superamphiphobic Coatings Based on Silica Particles Bearing Bifunctional Random Copolymers

Reported herein is the growth of bifunctional random copolymer chains from silica particles through a grafting from approach and the use of these copolymer-bearing particles to fabricate superamphiphobic coatings. The silica particles had a diameter of 90 +/- 7 nm and were prepared through a modified Stober process before atom transfer radical polymerization (ATRP) initiators were introduced onto their surfaces. Bifunctional copolymer chains bearing low-surface-free-energy fluorinated units and sol gel-forming units were then grafted from these silica particles by surface-initiated ATRP. Perfluorooctyl ethyl acrylate (FOEA) and 3-(triisopropyloxy)silylpropyl methacrylate (IPSMA) were respectively used as fluorinated and sol gel-forming monomers in this reaction. Hydrolyzing the IPSMA units in the presence of an acid catalyst yielded silica particles that were adorned with silanol-bearing copolymer chains. Coatings were prepared by spraying these hydrolyzed silica particles onto glass and cotton substrates. A series of four different copolymer-functionalized silica particles samples bearing copolymers with similar FOEA molar fractions (f(F)) of similar to 80% but with different copolymer grafting mass ratios (g(m)) that ranged between 12.3 wt % and 58.8 wt %, relative to silica, were prepared by varying the polymerization protocols. These copolymer-bearing silica particles with a g(m) exceeding 34.1 wt % were Used to coat glass and cotton substrates, yielding superamphiphobic surfaces. More importantly, these particulate-based coatings were robust and resistant to solvent extraction and NaOH etching thanks to the self-cross-linking of the copolymer chains and their covalent, attachment to the substrates.