Insights into the Synergistic Effect of Graphene Oxide/Silica Hybrid Nanofiller for Advancing the Properties of Epoxy Resin

Tuning the interfacial interaction between the filler and the matrix is essential to fabricate high-performance polymer nanocomposites. Herein, a hybrid nanofiller based on graphene oxide (GO) and nanosilica (SiO2) was prepared via electrostatic charge attraction. Amine-functionalized nanosilica was decorated over the surface of the GO sheet via simple aqueous mixing. The hybrid nanofiller approach of GO with nanosilica reduces the cohesive force between the GO sheets, facilitating better dispersion and thereby enhancing the properties of epoxies (preventing GO–GO and silica–silica agglomeration). The high-resolution transmission electron microscopy showed that the d spacing between GO sheets in the GO-SiO2 hybrid nanofiller (0.32 ± 0.70 nm) was higher than that in pristine GO. The synergistic effect of GO and nanosilica in the GO-SiO2 hybrid nanofiller of varying content (0.25 to 0.75 phr) as a reinforcement for advancing the properties of epoxies was monitored systematically. The effect of the GO-SiO2 hybrid nanofiller on the chain confinement, structure, and mechanics was studied by dynamic mechanical analysis. It was found that the hybrid nanofiller incorporation improved the filler matrix interaction and, thereby, the mechanical properties and glass transition temperature (Tg) of epoxy. Epoxy chains near the vicinity of the hybrid filler have become immobilized because of the strong filler-matrix interaction and form a confined zone around the filler-matrix interface. The quantitative measurement of the immobilized epoxy chains formed by the hybrid nanofiller was determined from the tan delta curve. A maximum enhancement in the storage modulus, Tg, impact strength, and other theoretical parameters was observed for epoxy nanocomposite with 0.5 phr loading of the hybrid nanofiller.