Ultra-hydrophobic sticky polymer surfaces formed by water-induced surface deformation.

Surface properties of poly(oxyethylene)s with alkyl thioether side chains (CH-nTE; n=carbon atoms in the side chain) were investigated. CH-nTEs having shorter side chains (n=6, 8, 10) did not have ordered structures, while those with longer chains (n=12, 14) showed well-ordered, lamellar structures with side chain crystalline domains. Accordingly, CH-12TE and CH-14TE film surfaces were much more enriched with hydrophobic alkyl side chains than CH-8TE and CH-10TE surfaces. However, CH-12TE and CH-14TE films had smaller water contact angles (≈114°) than CH-8TE and CH-10TE films (>130°). This unexpected behavior is ascribed to the formation of very rough CH-8TE and CH-10TE film surfaces (R>100nm) on contact with water. The CH-10TE/poly(methyl methacrylate) (PMMA) surfaces also showed high water contact angles (>125°), even with low CH-10TE content (30wt%), because the CH-10TE moiety roughened the surfaces. Furthermore, ultra-hydrophobic sticky behavior was observed for CH-nTEs (n=8, 10) and CH-10TE/PMMA surfaces.