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

Abstract

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 ( d 33 ), 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 revealed that the electrospun fiber mats showed predominantly β-PVDF. Interestingly, the highest β content was obtained in the presence of GOF. The drastic enhancement in β phase is due to the presence of highly electronegative fluorine. The addition of GOCOOH and GOF in PVDF not only increases the polar β phase but also changes the piezoelectric response significantly. More interestingly, PVDF/GOF films exhibited higher energy density and dielectric permittivity when compared with the control PVDF samples. These findings will help guide the researchers working in this field from both theoretical understanding and practical view point for energy storing device and charge storage electronics.

Electrospun PVDF Nanofibers for Piezoelectric Applications: A Review of the Influence of Electrospinning Parameters on the β Phase and Crystallinity Enhancement

“…Gebrekrstos et al have determined the maximum amplitude of three nanofibers PVDF/GO, PVDF/GOCOOH, and PVDF/GOF by PFM [ 153 ]. The d33 depends on the β phase content of PVDF nanofibers and is found to be increased with the increase of the β content.…”

Electrospun Polyvinylidene Fluoride-Based Fibrous Scaffolds with Piezoelectric Characteristics for Bone and Neural Tissue Engineering

“…In a recent study, Bose and coworkers employed carboxylated GO (CGO) and fluorinated GO (FGO) nanofillers for further enhancing d 33 value of PVDF fibrous mats. The highest β-phase content was achieved in the PVDF/1 wt% FGO mat due to the presence of highly electronegative fluorine [148]. Consequently, PVDF/1 wt% FGO fibrous mat had a high d 33 value of 63 pm/V.…”

Graphene impregnated electrospun nanofiber sensing materials: a comprehensive overview on bridging laboratory set-up to industry

“…4d, e. Gebrekrstos et al [161] reported that the addition of fluoro-doped graphene derivatives (GO, GOF and GOOCH) during electrospinning of polyvinylidene fluoride (PVDF) offered remarkable properties including enhanced electroactive β phase, high energy density and improved piezoelectric coefficient. This drastic enhancement can be ascribed to the increase in the amount of β The combination of the sulfonation, the crosslinking, and the addition of GO enhanced the proton conductivity [42] PVA/rGO in PVDF/GO fibers and the charge separation induced by the fluorine which acts as a polarization center.…”