Control of the functionality of graphene oxide for its in epoxy nanocomposites application

Amino- and epoxy-functionalized graphene oxide (GO) were synthesized separately through a wash- and-rebuild process utilizing two differently terminated silane coupling agents. The modified GO sheets were then incorporated into an epoxy resin to prepare nanocomposites. The addition of 0.2 wt% amino-functionalized GO (APTS-GO) yielded a 32% increase in Young's modulus (3.3 GPa) and 16% increase in tensile strength (81.2 MPa). Less reinforcement was observed with the epoxy-functionalized GO (GPTS-GO) but there was a more significant increase in ductility for GPTS-GO/epoxy, with the fracture toughness (critical intensity factor, KO and fracture energy (critical strain energy release rate, GO nearly doubling at 0.2 wt% loading (1.46 MPam(1/2) and 0.62 kJ/m(2) for K-IC and G(IC) respectively). Raman spectroscopy measurements revealed that the GPTS-GO was dispersed more uniformly than the APTS-GO in the epoxy matrix, and better interfacial stress transfer was found for the APTS-GO. Thus the wash-andrebuild process affords a novel strategy for controlling the functionality of graphene in the quest to develop high-performance graphene-based nanocomposites. (C) 2013 Elsevier Ltd. All rights reserved.