Reactive copolymer functionalized graphene sheet for enhanced mechanical and thermal properties of epoxy composites

Abstract

ABSTRACTUniform dispersion of graphene nanosheets (GNS) in a polymer matrix with strong filler–matrix interfacial interaction, preserving intrinsic material properties of GNS, is the critical factor for application of GNS in polymer composites. In this work, a novel reactive copolymer VCz–GMA containing carbazole and epoxide group was designed, synthesized and employed to noncovalently functionalize GNS for preparing epoxy nanocomposites with enhanced mechanical properties. The presence of carbazole groups in VCz–GMA enables the tight absorption of copolymer on to graphene surface via π–π stacking interaction, as evidenced by Raman and fluorescence spectroscopy, whereas the epoxide segments chemically reacts with the epoxy matrix, improving the compatibility and interaction of graphene with epoxy matrix. As a result, the VCz–GMA–GNS/epoxy composite showed a remarkable enhancement in both mechanical and thermal property than either the pure epoxy or the graphene/epoxy composites. The incorporation of 0.35 wt % VCz–GMA–GNS yields a tensile strength of 55.72 MPa and elongation at break of 3.45, which are 42 and 191% higher than the value of pure epoxy, respectively. Increased glass transition temperature and thermal stability of the epoxy composites were also observed. In addition, a significant enhancement in thermal conductivity was achieved with only 1 wt % VCz–GMA–GNS loading. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2776–2785