Effect of surfactant molecular structure on the electrical and thermal performance of epoxy/functionalized-graphene nanocomposites

摘要

In this study, three different moieties containing amino-groups were incorporated into graphene oxide (GO) in order to modify interfacial interactions within an epoxy matrix. The GO was functionalized with two bifunctional molecules of different molar masses (d230 and d4000) and a trifunctional (t440). The resulting functionalized GO (fGO) systems were characterized by Raman spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS), which demonstrated the presence of the functionalizer groups. Analysis of nanocomposites including the above three fGOs by microscopy and differential scanning calorimetry (DSC) demonstrated that the presence of the functionalizer moieties served to improve the platelet distribution within the matrix and to affect the local fGO/matrix interfacial interactions perturbing the epoxy curing reactions; we suggest that these changes stem from the fGO surface structure and the introduction of additional reactive amine nitrogen. X-ray diffraction revealed reduced graphitic stacking with increased functionalizer molar mass. The electrical conductivity of the fGO-filled epoxy was enhanced with increasing functionalizer molecular weight, an effect we relate to the influence of this on platelet stacking. The thermal conductivity was, however, adversely affected by all reagents at low fGO contents.