Ferroelectric properties of form I perdeuterated poly(vinylidene fluoride.)

We report the first D-E hysteresis measurements of perdeuterated poly(vinylidene fluoride), D-PVF sub 2, a newly synthesized polymer which has fewer chemical defects compared to any commercially available protonated PVF sub 2, H-PVF sub 2. The remanent polarization in the uniaxially oriented sample, when subjected to a triangular field signal with an amplitude of 250 MV/m, is 100 mC/m sup 2. This value is about 80% larger than the corresponding value of uniaxially oriented H-PVF sub 2 and comparable to the highest value (110 mC.M sup 2) reported for the copolymers of vinylidene fluoride and trifluoroethylene. However, whereas the copolymers lose their polarizations at temperatures below 140C, the D- PVF sub 2 sample is stable up to 170C. The large remanent polarization in D-PVF sub 2 is attributed to the higher crystallinity and crystalline order as a result of fewer chain defects in the polymer. This is confirmed by dielectric and calorimetric measurements which yield an estimated volume fraction of form I crystals of about 70% for D-PVF sub 2 and 45% for H-PVF sub 2.