Spectroscopic evidence for a high fraction of ferroelectric phase induced in electrospun polyvinylidene fluoride fibers

Abstract

Effective transformation from paraelectric to a high fraction of ferroelectric phase is crucial to produce piezoelectric materials with a high piezoelectric constant for broad applications. In polyvinylidene fluoride (PVDF) thin films, both mechanical stretching and electric poling processes have been found to be critical in the a / b phase transformation. However, in PVDF fibers fabricated by the electrospinning process, the roles of mechanical stretching and electric poling have not been well explored. Here, the properties of PVDF fibers from electrospinning and forcespinning, a mechanical spinning process without electric poling, have been characterized and analyzed by FTIR and XRD spectroscopic techniques. The results show that pure mechanical stretching in the forcespun fibers can result in a high fraction of the all-trans b-phase, at 95%. Electrospun fibers from the same material system, on the other hand, can also reach a high fraction of b-phase, at approximately 99%. These results preliminarily demonstrate that mechanical stretching is the main reason for b-phase induction in PVDF fibers. Further experiments performed in this work show that higher wt% of PVDF, lower polymer solution supply rate, and more uniformly mixed solvent systems facilitate achieving a higher level of ferroelectric b-phase in electrospun PVDF fibers.

Facile transformation of soot nanoparticles into nanoporous fibers via single-step electrospinning

“…18,19 The procedure for electrospinning experiment was well described in our previous study. 20 Briefly, the polymer solution was prepared by dissolving 0.979 g PVDF powder in 5.67 g DMF and 3.14 g acetone to form 10 wt% PVDF solution, and the same amount (0.979 g) of candle soots was gradually added with continuous stirring the mixture for 12 hours. Before the electrospinning process, the mixed solution was degassed to remove bubbles and the polymer solution flow rate was controlled using a precision pump (NE-300, New Era Pump Systems Inc).…”

Hybrid Energy Harvester Consisting of Piezoelectric Fibers with Largely Enhanced 20 V for Wearable and Muscle-Driven Applications

“…20 The key factors contribute to the highly efficient α→β phase due to the oriented unit cells of hydrogen and fluoride (CH 2 -CF 2 ) polar structure, β-phase is primarily responsible for PVDF's piezoelectric response. In order to largely enhanced the β-phase PVDF, electrical poling and mechanical stretching processes are indispensable to directionally align the dipoles in the crystalline PVDF structures.…”

Fabrication of three-dimensional nanofibrous macrostructures by electrospinning

“…The electrospinning apparatus for the fabrication of the 3D fibrous structures with/without fiber alignment was mostly the same as that described in the works done by Lei,17 and Mi, 18 except that the plate collectors were replaced with customized dynamic or static 3D collectors. The polymer solution flow rate was controlled by a high-precision pump (NE-300, New Era Pump Systems Inc).…”