Simultaneously Improved Dielectric Constant and Breakdown Strength of PVDF-based Composites with Polypyrrole Nanowire Encapsuled Molybdenum Disulfide Nanosheets

High-performance dielectric polymer composites have received increasing attention due to their important applications in the field of energy storage. The rational structural design of hybrid fillers can lead to a balance between high dielectric constant and insulation in composites. In this work, novel hybrid fillers were fabricated by in situ synthesizing one-dimensional polypyrrole nanowires (PPynws) on the two-dimensional molybdenum disulfide (MoS 2 ), which integrated the good ion polarization ability of PPynws and the high insulation and adjustable band gap of MoS 2 . Compared with the binary poly(vinylidene fluoride) (PVDF)/MoS 2 composites, the PVDF/MoS 2 -PPynws composites exhibited remarkably improved dielectric constant and breakdown strength, while the dielectric loss was still maintained at a low level. An optimal ternary composite with 1 wt% MoS 2 -PPynws showed a high dielectric constant (15@1kHz), suppressed dielectric loss (0.027@1kHz), and high breakdown strength (422.1 MV/m). PPynws inducing strong interfacial polarization and the highly insulated MoS 2 nanosheets extending the breakdown path mainly contributed to the synchronously enhanced dielectric constant and breakdown strength. This intriguing synthesis method of PVDF/MoS 2 -PPynws nanocomposite will open up new opportunities for fabricating nanostructured polymer composites to produce high dielectric materials.