Ferroelectric properties in PVDF/mica nanocomposites

Polyvinylidene fluoride is known to crystallize into a variety of polymorphs. Crystallization from the melt yields nonpolar Form II. Uniaxial-drawing induces transformation into Form I which is ferroelectric. It is known that an introduction of a small amount of trifluoroethylene causes direct crystallization into Form I without uniaxial-drawing. Recently a small amount of clay is also shown to be effective for crystallization into form I. However, the resulting film seems to be a mixture of Forms I and II, and exhibits relatively low remanent polarization Pr. In this paper, we use mica for clay and report on a finding of very large remanent polarization in the PVDF/mica nanocomposites prepared by melt crystallization and solvent casting