Functionalized graphene sheets for polymer nanocomposites

Polymer-based composites were heralded in the 1960s as a new paradigm for materials. By dispersing strong, highly stiff fibres in a polymer matrix, high-performance lightweight composites could be developed and tailored to individual applications 1 . Today we stand at a similar threshold in the realm of polymer nanocomposites with the promise of strong, durable, multifunctional materials with low nanofiller content 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 . However, the cost of nanoparticles, their availability and the challenges that remain to achieve good dispersion pose significant obstacles to these goals. Here, we report the creation of polymer nanocomposites with functionalized graphene sheets, which overcome these obstacles and provide superb polymer–particle interactions. An unprecedented shift in glass transition temperature of over 40 °C is obtained for poly(acrylonitrile) at 1 wt% functionalized graphene sheet, and with only 0.05 wt% functionalized graphene sheet in poly(methyl methacrylate) there is an improvement of nearly 30 °C. Modulus, ultimate strength and thermal stability follow a similar trend, with values for functionalized graphene sheet– poly(methyl methacrylate) rivaling those for single-walled carbon nanotube–poly(methyl methacrylate) composites. Nanocomposites reinforced with functionalized graphene sheets that form strong interactions with the surrounding polymer matrix are shown to have significantly enhanced thermal and mechanical properties.