Preparation and electroactive phase adjustment of Ag-doped poly(vinylidene fluoride) (PVDF) films

The crystallinities of Ag-doped poly(vinylidene fluoride) (PVDF) films were modified by removing Ag+ using a novel washing process, which allowed control of the ratio of gamma- and beta-phases. The polarity of the composite film without Ag+ removal through the washing process reached 98%, and the beta-phase content in the total electroactive phase was increased to 61%, according to Fourier-transform infrared spectroscopy. When Ag+ were removed through a process involving several cycles of washing, filtering, drying, and re-dissolving, the highest ratio of the gamma-phase was increased to 67%, 28% higher than that before washing. This showed that Ag+ induced beta-phase formation while Ag nanoparticles induced gamma-phase formation, and that the ratio of gamma- and beta-phases in PVDF composite films can be controlled to suit specific applications by this washing process.