Simultaneous reduction, functionalization and stitching of graphene oxide with ethylenediamine for composites application

A simple, efficient and cost-effective approach for the simultaneous reduction, surface modification and stitching of graphene oxide (GO) using ethylenediamine is described. The effect of stitched graphene on the mechanical properties of linear low density polyethylene (LLDPE)-based composites was also investigated. Ethylamine was used to produce unstitched graphene, of which structures and properties were compared to those of stitched graphene. The surface modification of GO with ethylamine or ethylenediamine can easily take place under mild conditions. The reduced GO (rGO) shows good crystalline behavior and high electrical conductivity (∼1075 S m^-1). The removal of epoxide, carboxyl and hydroxyl groups from GO by ethylamine or ethylenediamine was confirmed by Fourier transform infrared, Raman and photoelectron spectroscopy. The microstructures were analyzed by atomic force microscopy and transmission electron microscopy revealing stitching and crystalline behavior of the rGO. Compared to other reported methods, the reduction of GO with ethylamine and ethylenediamine is a preferable route for large-scale production of functionalized graphene. It was found that the storage modulus of the ethylenediamine functionalized GO (3 wt%)-LLDPE composites is significantly higher than that of pure LLDPE or ethylamine functionalized GO reinforced composites in the studied temperature range (-70 to 90 °C).