Improvement of the piezoelectric properties of PVDF-HFP using AgNWs

Abstract

In order to improve the piezoelectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), we added various amounts of silver nanowires (AgNWs) into PVDF-HFP and N,N-dimethylformamide (DMF) solution to prepare composite films. Stretching and poling were applied to the films to induce the formation of the polar β-phase and reorientation of the dipole moment. The crystal structure of the films was investigated by polarized optical microscopy (POM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The obtained results showed that the phase transformation mainly occurred in stretching and the reorientation of the dipole moment was attributed to poling. It was also concluded that the AgNWs played a role as nucleate agents in the β-phase formation and the phase transformation. The piezoelectric properties were also evaluated by the output voltage and harvested power density. It was found that the open circuit voltage of 0.1 wt% AgNWs containing films was 52% higher than that of pure PVDF-HFP films. Furthermore, the harvested power density was increased by 159%. Overdose of AgNWs resulted in crystal defects and the lower degree of crystallinity, leading to worse piezoelectric properties.