The α phase (or form II) of poly(vinylidene fluoride), PVF 2, produced from an acetone/ N, N -dimethylformamide (DMF) solution gave different surface morphologies, depending on the solvation temperature of the PVF 2 solution, the DMF concentration, and the relative humidity when deposited onto a smooth silicon substrate. Solutions prepared at less than 30 °C always gave rise to transparent films. However, solutions prepared at temperatures greater than 50 °C 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.
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Benz et al. (2000) studied this question.
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