The influence of preparation conditions on the surface morphology of poly(vinylidene fluoride) films

The alpha phase (or form II) of poly(vinylidene fluoride), PVF2, produced from an acetone/N,N-dimethylformamide (DMF) solution gave different surface morphologies, depending on-the solvation temperature of the PVF2 solution, the DMF concentration, and the relative humidity when deposited onto a smooth silicon substrate. Solutions prepared at less than 30 degreesC always gave rise to transparent films. However, solutions prepared at temperatures greater than 50 degreesC resulted in a rough and opaque, white. surface when depositing at high humidity and in a transparent film when depositing at low humidity. The aging behavior of the polymer solutions as measured by the viscosity revealed an enormous dependence on the DMF concentration. Optical light and atomic force microscopies and infrared spectroscopy characterized the differences of these film surfaces.