Poly (vinylidene fluoride) dielectric composites with both ionic nanoclusters and well dispersed graphene oxide

Nanostructured polymeric dielectric composites, based on poly (vinylidene fluoride) (PVDF), graphene oxide (GO), and an ionic liquid (IL), 1-vinyl-3-ethylimidazolium tetrafluoroborate ([VEIM] [BF4]), denoted as Nano-PVDF/IL/GO, were fabricated through casting method, electron beam (EB) irradiation and microphase separation processes. Through the strategy, GO nanosheets were dispersed homogeneously in PVDF matrix and the organic nanoclusters formed by microphase separation of IL grafted PVDF (PVDF-g-IL) chain segments tended to adhere onto the surface of GO nanosheets. The Nano-PVDF/IL/GO composites displayed a drastic reduction in dc conductivity compared with PVDF/GO and PVDF/IL/GO composites because of impeding the direct contact between GO nanosheets by the nanoclusters. Furthermore, the mircocapacitors between the adjacent GO nanosheets and nanoclusters contributed the increase of dielectric constant. At the same time, the dielectric loss from the current leakage of GO nanosheets was almost fully eliminated due to the strong interfacial bonding between polymer matrix and fillers which restrained the formation of conductive network. Therefore, we proposed an effective strategy for using the organic nanoclusters to modify the inorganic conductive fillers and impeding the formation of conductive network in the dielectric materials, which paves new possibility to prepare polymer nanocomposites with both high dielectric constant and low dielectric loss.

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