Water adsorption on and desorption from crystalline copolymers of vinylidene fluoride with trifluoroethylene.

Water adsorption and absorption on crystalline polyvinylidene fluoride with 30% trifluoroethylene, P(VDF-TrFE, 70:30), was examined by thermal desorption spectroscopy. Two distinctly different water adsorption sites are identified: one adsorbed species that resembles ice and another species that interacts more strongly with the polymer thin film. The existence of the latter species is consistent with X-ray diffraction studies of water absorbed into the bulk of copolymers of polyvinylidene fluoride with trifluoroethylene crystalline thin films. There are strong steric effects observed in the angle-resolved thermal desorption that may be a result of the large polymer thin film surface dipoles.