Surface chemistry of amphiphilic polysiloxane/triethyleneglycol-modified poly(pentafluorostyrene) block copolymer films before and after water immersion

New amphiphilic block copolymers Si-EFSx composed of a poly(dimethyl siloxane) (Si) block and a poly(4-(triethyleneglycol monomethyl ether)-2,3,5,6-tetrafluorostyrene) (EFS) block were synthesized by ATRP starting from a bromo-terminated Si macroinitiator. Similarly, new hydrophobic block copolymers Si-FSy consisting of an Si block and a poly(pentafluorostyrene) (FS) block were prepared for comparison. X-ray photoelectron spectroscopy (XPS) analysis on block copolymer films revealed that the Si block was concentrated at the polymer–air interface, while the EFS block was located in the layers underneath. The same polymer films underwent a marked surface reconstruction after immersion in water for seven days. This phenomenon involved the exposure of the hydrophilic oxyethylenic chains to contact water. Such surface reconstruction was even more drastic when an amphiphilic block copolymer was dispersed in a cross-linked poly(dimethyl siloxane) matrix film.