Graphene-polyethylene nanocomposites: Effect of graphene functionalization

The properties of polymer nanocomposites depend strongly on how well nanoparticles are dispersed. However, the hydrophobic nature and low polarity of PE have made effective dispersion of nano-filler difficult without compatibilization. We have found improved dispersion of chemically functionalized graphene oxide (FGO) in PE. The hydroxyl and epoxide groups on graphene oxide (GO) are sites for grafting on functional groups like alkanes. We covalently attach alkyl chains and benzyl moieties to GO. This FGO was solvent blended into three types of polyethylene: high density, linear low density, and oxidized PE matrices. Visual observation of cast films and optical micrographs revealed that FGO was more homogeneously dispersed than unmodified GO. Simple thermal reduction of the FGO sheets dispersed in PE at 210 °C achieved a 10⁶-fold reduction in electrical resistance, much greater than that of other unmodified graphene composites. Moreover the tensile modulus of the low density PE was improved 12-fold and that of the high density PE 3-fold with 5% FGO.