Enhancement of β-Phase Crystal Content of Poly(vinylidene fluoride) Nanofiber Web by Graphene and Electrospinning Parameters

Lu Jin,Yang-Pei-Qi Yi,Ze-Kun Liu,Jia-Shen Li,Yi Li,Yang-Yang Fan,Yan Zheng,Lu-Lu Xu

doi:10.1007/s10118-020-2428-4

Abstract

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability, and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD), and rotational speed of collector (RSC), as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influences of GC, TCD, and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that GC, TCD, and RSC all have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC = 1 wt%, TCD = 4 cm, and RSC = 2000 r-min−1) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, under which the crystallinity can reach 41.7%. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators.

Highlights

The results showed that graphene content (GC), to-collector distance (TCD), and rotational speed of collector (RSC) all have significant impact on the β-phase content of poly(vinylidene fluoride) (PVDF) nanofiber web, and GC is the most significant one (P < 0.05)
The results show that fractions of βphase (Fβ) increases with the increase of RSC, which means RSC has influence on Fβ of PVDF nanofiber web
A series of PVDF nanofiber webs have been fabricated with different GC and diverse electrospinning parameters, i.e. TCD and RSC

Summary

Introduction

Electroactive poly(vinylidene fluoride) (PVDF) has aroused great attention in view of its high piezoelectric coefficient, flexibility, and excellent processability, and been widely used in various electronic devices such as sensors, generators, and nonvolatile memories.[1,2,3,4,5,6,7,8] PVDF has several stable crystalline forms including α, β, and γ phases, which can be directly determined by preparation conditions.[9,10,11] Since β-phase shows the highest electrical dipole moment among three phases,[12,13] the content of β-phase plays a decisive role in PVDF nanofiber web based high-performance sensors and generators.[14,15,16] It is, of great importance to enhance the β-phase content of PVDF for the abovementioned applications.Electrospinning is a straightforward, scalable, and cost-effective versatile technique to fabricate high β-phase content of piezoelectric PVDF material, which is PVDF nanofiber web.[17,18,19,20] there are a huge number of parameters that influence the β-phase formation during PVDF electrospinning such as additive, tip-to-collector distance (TCD), rotational speed of collector (RSC), PVDF concentration, solvent mixture, applied voltage, injection flow rate, needle tip gage, Jin, L. et al / Chinese J. Electroactive poly(vinylidene fluoride) (PVDF) has aroused great attention in view of its high piezoelectric coefficient, flexibility, and excellent processability, and been widely used in various electronic devices such as sensors, generators, and nonvolatile memories.[1,2,3,4,5,6,7,8] PVDF has several stable crystalline forms including α, β, and γ phases, which can be directly determined by preparation conditions.[9,10,11] Since β-phase shows the highest electrical dipole moment among three phases,[12,13] the content of β-phase plays a decisive role in PVDF nanofiber web based high-performance sensors and generators.[14,15,16] It is, of great importance to enhance the β-phase content of PVDF for the abovementioned applications.

Methods

Results

Conclusion