Graphene oxide–polyamide 6 nanocomposites produced via in situ polymerization

Single layer graphene oxide (GO)–polyamide 6 (PA6) nanocomposites were produced via the in situ polymerization of ε-caprolactum dissolved in a water-based dispersion of single layer GO. As prepared GO and nanocomposites containing 0, 0.035, 0.076, 0.44 and 0.65 wt% GO in PA6 were characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Raman thermal analysis and tensile testing. XPS, AFM and TEM analyses confirmed that the modified Hummers method used to prepare the GO resulted in sheets of oxidized single layer graphene. It was observed using AFM that the in situ polymerization resulted in an efficient poly chain grafting and a reduction in the lateral dimensions of the sheets. The GO/PA6 nanocomposites showed an increased degradation temperature relative to neat PA6, which is an indicative of high levels of interfacial interaction and dispersion. It was observed that the addition of GO reduced the average PA6 molecular weight and acted as nucleation agent for α-form crystallinity while suppressing the formation of γ-form crystals. Mechanical reinforcement was also observed, with a tensile strength of 60.6 MPa recorded for PA6, rising incrementally with increased GO loading to 64.9 MPa at 0.65 wt%.