Simultaneous reduction and surface functionalization of graphene oxide and the application for rubber composites

The simultaneous reduction and functionalization of graphene oxide (GO) was realized through a chemical grafting reaction with a functionalization agent N,N-bis(3-aminopropyl)methylamine (APMEL). The reduced and functionalized reduced GO (rGO-APMEL) sheets can be well dispersed in water without any added surfactant and the formed stable rGO aqueous dispersion can be kept for a long time, which can be used for the preparation of rubber-graphene (GE) composites by latex mixing. The electrostatic interaction between rGO-APMEL (positively charged) and natural rubber latex particles (negatively charged) leads to the formation of NR/rGO-APMEL composites with strong interaction. Compared with blank NR, the tensile strength and modulus for NR/rGO-APMEL increase with the rGO-APMEL loading. Especially, when the filler content is 5 phr, the tensile strength of NR/rGO-APMEL-5 increases by 32.7%, as a control the tensile strength of NR/GO-5 and NR/rGO-5 decrease by 20.1 and 15.6%, respectively. The entanglement-bound rubber tube model was used to analyze the reinforcing effect of GE on NR/rGO-APMEL nanocomposites at a molecular level. This study may provide us a novel approach to prepare well dispersed and exfoliated rGO-polymer nanocomposites.