Substrate effects on crystallization of polyvinylidene fluoride from solution

Abstract

Different concentrations of the α, β and γ polymorphs of polyvinylidene fluoride (PVDF) result on casting from solution onto substrates of steel, aluminium, Teflon^R, copper, gold and silicon. The polymer solution was in contact with the oxides of the metals, and with the (100) surface of the silicon monocrystals. X-ray diffraction, infrared spectroscopy, polarized optical and scanning electron microscopy show that iron and aluminium oxide substrates promote crystallization of PVDF mainly in the a form. Copper oxide and gold strongly stimulate the β form with some α form. Teflon favours the α form, and silicon the β form. Specimens cast on silicon yield a highly oriented “columnar” structure perpendicular to the film surface, and show a pyroelectric response without any previously applied electric field. Some interesting results were obtained from attempts to match the polymer—oxides and polymer—metal lattices.