Highly Transparent PVDF Films with Enhanced Dielectric and Energy Storage Properties Tailored by a PMMA-co-GMA Copolymer

Abstract

High losses and low efficiency have been the main defects limiting poly(vinylidene fluoride) (PVDF) as an energy storage film capacitor material. Herein, the linear methyl methacrylate-co-glycidyl methacrylate (MG) copolymer was prepared to improve the dielectric and energy storage performance of PVDF. FTIR spectroscopy and XRD results showed that the introduction of MG induced the crystal phase transformation of PVDF. Polarized optical microscopy and DSC tests proved the smaller crystal size and lower crystallinity of PVDF in the composites. The introduction of MG decreased the permittivity of PVDF and suppressed dielectric and conductive losses. The composites showed higher breakdown strength, which increased from 300 MV/m for PVDF to 540 MV/m for the PVDF/MG-40% composite. Despite the weak polarity of MG, the complementary breakdown strength endowed excellent discharge energy density and efficiency for the PVDF/MG composites. The discharge energy density increased from 3.75 J/cm 3 for PVDF to 9.2 J/cm 3 for the PVDF/MG-40% composite. Meanwhile, the PVDF/MG-40% composite still maintained a high efficiency of 84% even at a 540 MV/m electric field. This research provides a feasible design idea for all-organic composite membranes. More importantly, the reactive activity of epoxy groups on the MG copolymer can be utilized for later performance optimization of PVDF/MG dielectric membrane through regulation strategies.

All-organic PVDF-based composite films with high energy density and efficiency synergistically tailored by MMA-co-GMA copolymer and cyanoethylated cellulose

“…According to our previously study, the crystalline phase of PVDF/MG (60/40, wt/wt) composites is dominated by the b-phase. 28 In Fig. 1(a), the characteristic peaks of PVDF for the typical a-phase at 764, 796, and 976 cm À1 are not present.…”

“…The preparation of the PVDF/MG ferroelectric composite matrix was performed according to a previous study (MG accounts for 40 wt%.). 28 Cyanoethylated cellulose (CR-C) was obtained from PolyK Technologies Company (USA). CR-C was dissolved in the N , N -dimethylformamide (DMF) solvent and DMF was purchased from China Pharmaceutical Group Co., Ltd.…”

“…26 Compared with PMMA, the MMA-co-GMA (MG) copolymer has a higher dielectric constant and stronger electric breakdown strength, and is miscible with PVDF, resulting in a greater improvement of crystal morphology and U e of PVDF. 27,28 As a result of our previously published research, the introduction of MG into PVDF promoted the formation of hydrogen bonds, which was useful for enhancing the trap energy level due to the epoxy groups of GMA on the MG macromolecular chains, thus inhibiting the carrier's transportation and delivery. 27 Therefore, the E b and U e of the composites reached the maximum when PVDF was blended with MG at 40% content.…”

“…27 Therefore, the E b and U e of the composites reached the maximum when PVDF was blended with MG at 40% content. 28 In recent years, most researchers would like to utilize biorenewable polymers to replace traditional chemical raw materials for the preparation of dielectric films. Cellulose is widely known as one of the most widely distributed and abundant polysaccharides in nature and possesses the advantages of nonpollution, renewability, wide source, low price, and so on.…”

“…27 Therefore, the E b and U e of the composites reached the maximum when PVDF was blended with MG at 40% content. 28…”