Synergistic diameter control and post-treatment engineering of electrospun PVDF nanofibers toward β-phase enrichment and enhanced piezoelectric response

The development of high-performance flexible piezoelectric materials is essential for next-generation wearable and self-powered electronic devices. Poly(vinylidene fluoride) (PVDF), a representative piezoelectric polymer, suffers from an intrinsically limited piezoelectric response, which is primarily governed by the content and orientation of the electroactive β-phase. Conventional strategies for β-phase enhancement often involve complex processing with limited efficiency and scalability. Here, we report a facile and scalable electrospinning strategy for fabricating PVDF nanofiber mats with uniform and tunable diameters ranging from 100 to 1000 nm, achieved by regulating polymer molecular weight and solution parameters. A systematic investigation reveals a pronounced diameter-dependent enhancement of the β-phase content, with finer nanofibers exhibiting significantly higher electroactive phase fractions. To further improve the piezoelectric performance, a synergistic post-treatment combining multi-temperature thermal annealing and bias-controlled grid-corona poling was employed, leading to enhanced crystallinity and more efficient dipole alignment. As a result, ultrafine PVDF nanofibers with diameters of approximately 100 nm achieved a β-phase content of 95.1%, a crystallinity of 0.541, and an effective piezoelectric coefficient of 136.0 pC N−1, which is approximately 4–5 times higher than that of commercial PVDF films, together with a high sensitivity of 362.0 mV N−1. This work elucidates the coupled effects of nanoscale confinement and post-treatment on the structure–property relationships of PVDF nanofibers, providing practical insights for the scalable development of high-performance piezoelectric polymer materials.