The Influence of Interfacial Graphene on the Morphological, Electrical and Mechanical Properties of Co-Continuous Polymer Blends

Interfacial localization of conductive fillers at the interfaces in co-continuous polymer blends is shown to be effective in suppressing the coarsening of co-continuous structure during annealing and increasing conductivity with a low electrical percolation threshold. In this study, two different conductive fillers—graphene nanoplatelets (GnPs) and thermally reduced graphene oxide (r-GO)—were melt compounded with polyethylene terephthalate glycol-modified (PETG) and polystyrene (PS) blends to prepare ternary co-continuous polymer composites. The morphological, electrical and mechanical properties of the resulting composites were systemically investigated. Through transmission electron microscopy (TEM) micrographs, we showed that GnPs transferred from the premixed PETG phase to the thermodynamically favored PS phase during the melt compounding, whereas most r-GO trapped at the interface of the polymer blends. Such a difference in the distribution of conductive fillers leads to drastic differences in the morphological, electrical and mechanical properties of the ternary composites. Particularly, we found that the interfacial r-GO greatly improved the Young’s modulus and fracture toughness of the co-continuous polymer blends.