A novel water-based mechanochemical approach for surface modification of graphene platelets and their epoxy nanocomposites

Graphene (nano) platelets (GPs) are cost-effective and possess high structural integrity, but their limited surface functional groups hinder their compatibility with polymers. In this study, an eco-friendly, water-based mechanochemical approach was developed to modify GPs with polyacrylamide (PAM), creating PAM graphene platelets (PAM-GPs) with a grafting ratio of approximately 15%. The platelet was measured to be a few nanometers in thickness, and the grafted PAM provides abundant functional groups, including amide groups, which enhance compatibility with polymers. A typical polymer, bisphenol-A epoxy, was compounded with PAM-GPs, resulting in a high degree of exfoliation and dispersion of PAM-GPs within the matrix. The resulting epoxy/PAM-GP composites exhibited significantly improved mechanical properties, including an 18% increase in Young's modulus and a substantial enhancement in fracture toughness, with a 71% increase at a low filler fraction of 0.5 wt%. These improvements are attributed to the effective interfacial interaction between the PAM-GPs and the epoxy matrix, facilitated by the grafted functional groups. This study highlights the potential of PAM-GPs as toughening fillers for epoxy composites, emphasizing their applicability in enhancing the durability and performance of structural components in industrial applications.Highlights Polyacrylamide (PAM)-modified graphene platelets by a water-based approach. A strong interface promoted exfoliation and dispersion of platelets. PAM-modified platelets improved epoxy modulus and toughness. Fractographic analysis unveils toughening mechanisms. X-ray diffraction indicating outstanding exfoliation and dispersion of polyacrylamide-modified graphene platelets, compared to the unmodified platelets, within the epoxy matrix. image