High dielectric polymer composites from thermal-induced in-situ formation of conjugated structures and reduced graphene oxide

Fabrication of high-dielectric polymer-matrix composites by adding inorganic fillers has attracted much attention, while great challenge is posed on the trade-off between enhancement of dielectric permittivity and sacrifice of mechanical flexibility. In this work, we report in-Situ formation of conductive filler strategy for making composites with significantly enhanced dielectric permittivity while well-retained mechanical flexibility. In detail, a trace amount (1.0 wt%) of graphene oxide (GO) is added into a polymer blend of polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN). After thermal annealing, the PAN and GO are simultaneously converted to conjugated structures (PCS) and reduced graphene oxide (rGO), respectively. The dielectric permittivity of resulting composites is enhanced due to the synergistic contribution between the in-Situ formed PCS and rGO conductive networks, which shows a high permittivity of 180.85 (PVDF/PCS/rGO, 20 wt% PVDF). Besides, the mechanical and thermal properties of the PVDF/PCS/rGO composites just slightly decreased owing to the trace amounts of inorganic fillers. Therefore, the prepared PVDF/PCS/rGO material with good dielectric, mechanical, and thermal property is promising flexible electronics.