Ionic Liquid Assisted Dispersion of Reduced Graphene Oxide in Epoxy Composites with Improved Mechanical Properties

Graphene nanosheets were prepared by chemical reduction of the exfoliated graphite oxide using sodium borohydride (NaBH4). The graphene/epoxy composites were separately fabricated in the absence or presence of imidazolium-based ionic liquids, and their dynamic thermomechanical and tensile properties were studied. TEM examinations show that graphene sheets are well dispersed in the epoxy resin and have strong interface adhesion with the matrix due to the pi-pi and/or cation-pi interactions between graphene and imidazolium ions. The composite fabricated by assistance of ionic liquids shows larger increases in Young's modulus, tensile strength, storage modulus and glass transition temperature compared to the composite without using ionic liquids. This work provides a method for the fabrication of multifunctional graphene-based polymer composites.