Structure dependent piezoelectricity in electrospun PVDF-SiC nanoenergy harvesters

Abstract

Piezoelectric materials are undeniably one of the most critical advanced materials in the modern era that can be used as energy harvesters and sensors. In many of these applications, flexibility is a key factor in guaranteeing the proper performance and durability of the device. Polyvinylidene fluoride (PVDF) is a structure-dependent piezoelectric polymer that can provide the required flexibility and piezo-response in its electroactive β-phase structure. The present research aims to investigate the effect of SiC additive and process parameters on the β phase formation in electrospun PVDF fibers. For this purpose, PVDF/SiC nanocomposites were prepared by the electrospinning method, and the effects of PVDF solution concentration, SiC wt%, and electrospinning voltage on β-phase fraction were studied using response surface methodology (RSM) approach for experimental design. The uniform and bead-free morphology of the fibers was observed using scanning electron microscopy (SEM). The results showed that the highest β content could be obtained at low PVDF concentrations, high electrospinning voltage and high SiC wt%. The dominant crystalline phase was determined by XRD analysis, and the β-phase fraction in nanocomposites containing different SiC loadings was estimated using FTIR spectroscopy. The presence of SiC nanoparticles enhanced the piezoelectric behavior of PVDF/SiC nanocomposites due to the higher β-phase fraction and improved charge transfer in the vicinity of semiconductive SiC nanoparticles. The optimum sample containing 3.98 wt% SiC nanoparticles was composed of 95.9% β-phase and showed a normalized piezoelectric sensitivity of 0.4737 mV/N, which was improved by about 350% compared to pure PVDF fibers. The obtained results show that PVDF/SiC nanocomposite fibers can be a promising choice for nanoenergy harvesters or flexible sensors with high sensitivity to small external loads. • RSM optimization was performed on the fabrication process of PVDF-SiC fibers. • β fraction was increased with voltage and SiC wt% and decreased with PVDF concentration. • PVDF-SiC nanocomposite fibers generate a significant output voltage upon loading. • 350% increase was observed in piezoelectric sensitivity of optimized PVDF-SiC fibers. • The piezoresponse enhancement was due to higher β fraction and better charge transfer in the vicinity of SiC nanoparticles.