The Role of Solution Phase Water on the Deposition of Thin Films of Poly(vinylidene fluoride)

Thin films of PVDF were deposited from a variety of solution conditions and examined by IR spectroscopy and scanning electron microscopy. Methods to rapidly assess the film thickness and the phase composition of PVDF films have been developed. In particular, the formation of the ferroelectric β phase can be controlled by the composition of the solvent, notably the water content. Using a hydrated salt in the casting solvent reproducibly formed films with high β phase content. However, the water also induces increased surface roughness in the deposited films. The nature of the PVDF films also is influenced by the kinetics of the evaporation process, and this was followed by IR spectroscopy. The rate constants depend on both the film thickness and the gas-phase humidity, indicating that solvent diffusion is an important contributor to both the bulk phase composition and the surface structure of the polymer films.