γ-Phase nucleation and electrical response of poly(vinylidene fluoride)/microporous titanosilicates composites

Microporous titanosilicates ETS-10, ETS-4 and GTS-1 were applied in the preparation of poly(vinylidene fluoride), PVDF, composites by solvent casting and melt crystallization. The spherulitic microstructure of neat PVDF is maintained but the crystallization phase is altered to the piezoelectric γ-phase when the sample is melted at temperatures below 200 °C. The crystallinity and the temperature of polymer degradation are hardly influenced by the introduced titanosilicates, however ETS-4 incorporated in the polymer showed improved thermal stability. The dimensional characteristics of the porous framework, different confined mobility of the charge compensating cations and the interfacial polarization led to gradually increased dielectric constant that reached values of 18 at 1 kHz. This behavior was accompanied by increased dielectric losses and a.c. conductivity. The reported PVDF/microporous titanosilicate composites represent a new class of materials with application potential for sensors and actuators.