(173f) Does Graphene Increase Tg of Polymer Nanocomposites?

Ken-Hsuan Liao¹, Steven Maslo¹, Shingo Kobayashi¹, Hyunwoo Kim², Ahmed Abdala³, Chris Macosko¹

¹Chemical Engineering & Materials Sciences, University of Minnesota, Minneapolis MN; ²The Dow Chemical Co., Midland MI; ³Chemical Engineering, The Petroleum Institute, Abu Dhabi UAE

Graphene recently has attracted large interest because of its 2-D structure, outstanding electrical and mechanical properties. Due to the high surface area and aspect ratio, graphene is capable to improve polymers' mechanical properties, gas impermeability and electrical conductivities. However, there is considerable disagreement as to whether the glass transition temperature (T_g) changes with incorporation of graphene in polymers. We review the literature and find that solvent or melt blending of graphene with typical thermoplastics does not result in a change in polymer T_g.  However, aqueous-soluble polymer which can form strong hydrogen bonds with graphene derived from graphene oxide (GO) can show a significant T_g increase. Also blending polymers with chemically modified graphene or in situ polymerization of monomers in the presence of GO derived graphene, are capable to provide strong covalent bonds between matrix polymers and fillers, which cause T_g increase. We illustrate this with new experiments on PMMA.