Grafting of polystyrene onto reduced graphene oxide by emulsion polymerization for dielectric polymer composites: High dielectric constant and low dielectric loss tuned by varied grafting amount of polystyrene

5 years ago

Grafting of polystyrene onto reduced graphene oxide by emulsion polymerization for dielectric polymer composites: High dielectric constant and low dielectric loss tuned by varied grafting amount of polystyrene

In this work, polystyrene-grafted reduced graphene oxides (rGO-PS) were prepared via the emulsion polymerization with reserving the two-dimensional layer-like structure of graphene. TGA, FTIR, Raman results show that the amounts of polystyrene (PS) grafted on rGO from low to medium, high values can be tuned via incorporating different content of styrene in the PS polymerization recipe. Subsequently a series of PS-based composites containing different loading of rGO with variant amount of PS grafted on rGO were prepared. The effects of grafting amount on the resulting dielectric properties were carefully investigated. Compared with the composites containing rGO without any treatment, significantly increased dielectric constant and lower dielectric loss are observed for the composites with rGO-PS. Moreover, with increasing the amounts of grafted PS on rGO, the dielectric constants exhibit an increasing trend whereas the dielectric loss keeps at a stable level. For instance, when the loading of filler is fixed at 5wt%, the composites containing rGOs with highest amount of grafted PS exhibit a maximum of dielectric constant 394.6@100Hz, which is over 20 times larger than that of composites containing rGO. However, a relatively low dielectric loss tangent 0.45@100Hz and conductivity 4.04×10⁻⁹ S/cm@100Hz are observed in the composites containing rGOs with highest amount of grafted PS, which is even lower than that of composites containing rGO. The improved interfacial polarization induced by the constructed PS layer between rGO and PS matrix is invoked to be responsible for the improved dielectric constant; on the other hand, the PS layer can restrict the conduction loss and suppress the dielectric loss. This work indicates that the dielectric performance of composites could be effectively ameliorated through the strategy of reasonably designing the interface structure of conductive fillers.

Publisher URL: www.sciencedirect.com/science

DOI: S0014305717308984