Study of factors affecting the formation of a gradient structure in acrylate copolymer/fluoro-copolymer blends

The effects of the solution concentration and the rate of solvent evaporation on the formation of gradient structures were examined for poly(2-ethylhexyl acrylate-co-acrylic acid-co-vinyl acetate) [P(2EHA-AA-VAc)]/poly(vinylidene fluoride-co-hexafluoro-acetone) [P(VDF-HFA)] blends. When the 30/70 P(2EHA-AA-VAc)/P(VDF-HFA) blend was prepared from 10 wt% THF solution, a gradient structure was not formed. When the 70/30, 50/50, and 30/70 P(2EHA-AA-VAc)/P(VDF-HFA) blends were prepared by casting from 5 wt% tetrahydrofuran (THF) solution onto poly(tetrafluoroethylene) (PTFE), the chemical compositions of the surface and bottom sides of the blends were different depending on the blend ratio and rate of solvent evaporation. Therefore, it was concluded that the formation of a gradient structure is strongly influenced by the solution concentration and the rate of solvent evaporation.