Enhanced dielectric properties of poly(dimethyl siloxane) bimodal network percolative composite with chemically modified graphene

Bimodal network composite was prepared using a two-step method containing graphene modified by γ-(2, 3-epoxypropoxy) propyl trimethoxysilane (KH560), short chain poly(dimethyl siloxane) (C S -PDMS) and long chain poly(dimethyl siloxane) filled with treated fumed silica (C L -h-PDMS). A series of composites with different filler contents (including reduced graphene oxide and reduced graphene oxide grafted with KH560, referred to rGO and KrGO, respectively) were prepared to explore their percolation thresholds ( fc ). We discover that the dielectric constant and loss of 1.32 vol% KrGO/h-PDMS composite were 18.8 and 0.13 at 10 2  Hz before fc , respectively, which was 2.1 and 0.12 times that of rGO/h-PDMS, and 6.6 and 2.1 times that of pure h-PDMS. The origin is that KH560 insulting layer increases the interlayer distance of graphene sheets to cut down the leakage current . In addition, the modulus of 1.32 vol% KrGO/h-PDMS is less than 3 MPa.