Low-cost Free-standing ferroelectric polymer films with high polarization produced via pressing-and-folding

Ferroelectric polymer poly (vinylidene fluoride) (PVDF) shows excellent electro-activity and is promising for flexible electronic devices. However, the processing of PVDF into the favourable ferroelectric structure (beta-phase) presents difficulties, while its copolymer with trifluoroethylene (PVDF-TrFE) can directly crystallize into beta-phase, but shows limited thermal stability and high-cost processing. As a result, an easily implementable method, pressing-and-folding (P&F), was used to produce highly compatible blended films of PVDF and PVDF-TrFE without using any hazardous solvent or complex polymer processing equipment. Hot-pressed PVDF (molecular weight: 530 kg/mol) and PVDF-TrFE (molar ratio: 51/49) films were firstly stacked before undergoing P&F treatment. Compared to extrusion-blended films before and after P&F, the P&F stacked films showed isotropic crystalline structure of beta-phase, as confirmed using X-ray diffraction and infrared spectroscopy. The ferroelectric remnant polarization of the P&F stacked films is 0.068 C/m(2), surpassing pure PVDF-TrFE (0.062 C/m(2)) and the simulated value of remnant polarization of pure PVDF (similar to 0.065 C/m(2)). The above findings promise to provide inspirations for new processing strategy on PVDF-based functional polymers. (C) 2021 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.

Automated summary

Ferroelectric polymer poly (vinylidene fluoride) (PVDF) and its copolymer with trifluoroethylene (PVDF-TrFE) were successfully processed into highly compatible blended films of isotropic crystalline structure using a pressing-and-folding method. The blended films showed excellent ferroelectric properties, surpassing the pure PVDF-TrFE and pure PVDF.