Microcapacitance-Enhanced Nanostructured Polyvinylidene Fluoride Composites for Enhanced Energy Storage and Flexible Piezoelectric Sensing Applications

This article describes a significant enhancement of the piezoelectric properties of poly(vinylidene fluoride) (PVDF) through interfacial engineering and a magnetically oriented structural design. Reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry were used to graft three polyionic liquids (PILs) with different alkyl chain lengths onto the surface of MXene. This successfully suppressed MXene’s self-stacking problem and enhanced its compatibility with PVDF. Next, Fe3O4 nanoparticles were introduced to impart a magnetic response, followed by a solution-melt synergistic "piezo-folding cycle” process to induce the formation of the β-phase. In the experiments, this resulted in a piezoelectric coefficient (d33) of 45 pC/N, a 15-fold increase compared to pure PVDF (∼3 pC/N). The resulting piezoelectric nanogenerator (PENG) produces an output current of 0.2 mA at a 120 N load and exhibits a sensitivity of 6.67 µV/N. This work demonstrates the effectiveness of using MXene to induce piezoelectricity in PVDF.本研究报道了通过界面工程与磁取向结构设计，显著提升聚偏氟乙烯（poly(vinylidene fluoride), PVDF）压电性能的工作。研究人员采用可逆加成断裂链转移聚合（Reversible addition-fragmentation chain transfer, RAFT）与点击化学方法，将三种烷基链长度不同的聚离子液体（polyionic liquids, PILs）接枝至MXene表面，有效抑制了MXene的自堆叠问题，并提升了其与PVDF的相容性。随后引入四氧化三铁纳米颗粒赋予体系磁响应性，再通过固液协同“压电折叠循环”工艺诱导PVDF形成β晶型。实验结果表明，该体系的压电系数（d33）可达45 pC/N，相较于纯PVDF（约3 pC/N）提升了15倍。所制备的压电纳米发电机（piezoelectric nanogenerator, PENG）在120 N载荷下输出电流为0.2 mA，灵敏度达6.67 µV/N。本工作证实了利用MXene诱导PVDF产生压电性能的有效性。