Enhance the piezoelectricity of poly(vinylidene fluoride) through co-crystal with polycaprolactone

The strategies of solid solution and doping have been well-established obtaining high piezoelectric ceramics, achieving a significant increase in the piezoelectric coefficient. Nevertheless, there is a paucity of research investigating this strategy in polymer piezoelectric materials. In this work, we present a novel approach to co-crystal formation between polycaprolactone (PCL) and poly(vinylidene fluoride) (PVDF), which markedly enhances the piezoelectricity of PVDF. The formation of a co-crystal results in a notable reduction in the crystal size of PVDF, an increase in the interface between the crystalline and amorphous regions, and the directional arrangement of dipoles under an electric field. The piezoelectric coefficient of the 3 % PCL/PVDF film is approximately twice that of the commercial PVDF film (22.0 pC/N), and the sensor device exhibits favorable linear sensing characteristics. The present study proposes a novel strategy for the development of films with exceptional piezoelectric properties.