Graphene oxide dispersion state in polystyrene-based composites below percolation threshold via linear melt rheology

In this work, the relation between the morphological structure and the linear viscoelasticity of graphene oxide (GO)-based polystyrene nanocomposites below percolation threshold was investigated. The rheological properties were observed to change upon addition of GO-2D particles at filler content below mechanical percolation threshold (0.06–0.3 %vol). In particular, the nanocomposite systems showed a delayed long-range relaxation dynamic regardless particle concentration, when compared to the neat polystyrene matrix. Moreover, little shift with regard to higher relaxation times of the full relaxation spectra of PS-GO nanocomposite was observed. This is attributed to the presence of attractive-kind interfacial interaction between polymer chains and GO-2D particles via π-π binding of benzyl rings, which strongly depends on GO sheets dispersion and exfoliation state. In light of these observations, oscillatory shear rheology measurements were used as an indirect tool to establish how exfoliated GO-2D particles were homogeneously dispersed in a low-polar polymer matrix. Graphical abstract The addition of GO-2D particles into polystyrene matrix at filler content below percolation threshold induces a pronounced retardation response of polymer chains in flow compared to the neat matrix. Attractive π-π interactions among benzyl groups from polystyrene chains and graphitic sheets play the major role and determine the GO-2D particles exfoliation level.