Effect of solvent evaporation rate on surface composition in fluoro-copolymer/acrylate-copolymer blend films

The relationship between the surface composition and the rate of solvent ev aporation (R) in blend films of poly(vinylidene fluoride-co-hexafluoroaceto ne) (P(VDF-HFA)) and poly(2-ethylhexyl acrylate-co-acrylic acid-co-vinyl ac etate) (P(2EHA-AA-VAc)) has been investigated. P(VDF-HFA), a low-surface te nsion component, was concentrated on the surface when R was relatively high . In contrast, when R was relatively low, P(2EHA-AA-VAc), a low-density com ponent, was concentrated on the surface. Therefore, it is speculated that t he factors dominating surface enrichment in polymer blends were changed fro m surface tension differences to density differences between the components when R was decreased. In addition, the affinity between components and sub strate strongly affects the dominant factors determining the surface compos ition. (C) 2001 Society of Chemical Industry.