High throughput modification of chemically reduced graphene oxides by a conjugated block copolymer in non-polar medium

We present a simple, but robust route to efficiently disperse very high rGO concentrations of chemically reduced graphene oxides (rGOs) in various non-polar solvents and polymers. Our method is based on the noncovalent, nondestructive modification of rGOs with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). The dispersion of rGOs occurred because PPP blocks strongly adhered to basal planes of rGOs by π-π interactions, while PS blocks provided good solubility in a variety of non-polar environments. The resulting PS-b-PPP modified rGOs (PMrGOs) showed excellent solubility and dispersion stability that was dependent on the quality of the solvent with respect to the PS blocks. In particular, extremely high solubility of the rGOs, as high as 1.5 mg mL^-1, was achieved in THF. Our PMrGOs and their solution blends with other non-polymer polymers such as PS, poly(methylmethacrylate) and poly(isoprene-block-styrene) were conveniently spin-coated on various substrates, giving rise to ultra-thin nanohybrid films where the amount of rGO can be systematically controlled. The scalable and simple strategy employed for fabricating rGO nanohybrid films allowed us to assemble a high performance non-volatile resistive polymer memory device in which the bias-dependent trapping and de-trapping of injected charges were efficiently manipulated on the surface of highly dispersed rGO sheets in the nanohybrid.