Piezoelectric Response in Electrospun Poly(vinylidenefluoride) Fibers Containing Fluoro-Doped Graphene Derivatives

摘要

Herein, graphene oxide (GO) was suitably functionalized to obtain carboxylated and fluorinated GO (GOCOOH and GOF) derivatives, respectively, via the Hunsdiecker reaction. Electrospun mats of poly(vinylidene fluoride) (PVDF)/GO, PVDF/GOCOOH, and PVDF/GOF fibers were then prepared by electrospinning from well-dispersed GO derivatives. The piezoelectric coefficient (d33), as measured using piezoelectric force measurement (PFM), enhanced by more than 2 folds with respect to the control PVDF spun mat. The piezoelectric coefficient though enhanced upon the addition of GO and GOCOOH, however, enhanced significantly in the case of GOF. For instance, a drastic increase in piezoelectric response from 30 pm V^–1(electrospun neat PVDF) to 63 pm V^–1 (for electrospun PVDF/GOF) was observed as revealed from PFM results. The phase transformation in these fibers was systematically investigated by various techniques such as Fourier transform infrared spectroscopy (FTIR), wide angle X-ray diffraction (XRD), Raman spectroscopy, and PFM. FTIR and XRD results revealedthat the electrospun fiber mats showed predominantly β-PVDF.Interestingly, the highest β content was obtained in the presenceof GOF. The drastic enhancement in β phase is due to the presenceof highly electronegative fluorine. The addition of GOCOOH and GOFin PVDF not only increases the polar β phase but also changesthe piezoelectric response significantly. More interestingly, PVDF/GOFfilms exhibited higher energy density and dielectric permittivitywhen compared with the control PVDF samples. These findings will helpguide the researchers working in this field from both theoreticalunderstanding and practical view point for energy storing device andcharge storage electronics.