Polymer Nanocomposites: In Situ Polymerization of Polyamide 6 in the Presence of Graphene Oxide

Polyamide 6 (PA6)/graphene oxide (GO) nanocomposites were prepared via in situ, ring opening polymerization of e-caprolactam in the presence of both dried powder and colloidally dispersed single layer GO. Characterization of the composites and GO (both as received and after removal from the composites) was carried out using atomic force microscopy (AFM), Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry and tensile testing. Reduction in the GO during polymerization was observed. So too was functionalization of the GO flakes with PA6 chains. FTIR demonstrates the retention of some carbonyl oxygen functionalities after polymerization. AFM imaging indicated the presence of single layer GO and the sheet height increased to similar to 4 nm for graphene sheets after polymerization. This suggests the graphene acts as a base for polymer chain formation, leading to good interfacial interaction between the filler and matrix. Raman data show no evidence of the restoration of sp2 hybrid as a result of polymerization. The nanocomposites are thermally stable while molecular weight and crystallinity have both been affected by GO inclusion. A percentage linear increase in Young's modulus was observed as colloidally dispersed GO content increased. (C) 2015 Society of Plastics Engineers