Investigation of Electrical Properties of Graphene-Based Nanocomposites Supported by Tunnelling AFM (TUNA)

摘要

The present study concerns the electrical properties of epoxy-/amine-based composites filled with two types of exfoliated graphite nanoparticles, i.e. partially exfoliated graphite (pEG) and carboxylated partially exfoliated graphite (CpEG), that differ in the exfoliation degree (56% and 60%, respectively) and hence for the content of carboxylate groups. The morphological analysis reveals that both graphene-based nanoparticles are homogenously dispersed within the epoxy/amine matrix. The amount of the two fillers influences the overall electrical performance of the resulting nanocomposites. In particular, it is found that the incorporation of CpEG leads to a very low percolation threshold (EPT) in the range [0.025-0.1 ] wt% and a relatively high electrical conductivity (about 0.096 S/m at 1.8 wt% of loading). These results are due to the higher exfoliation degree and the presence of carboxylate groups on the edges of the nanoparticles. which are responsible for weak attractive intermolecular bonds that favour the formation of the conducting network through a sort of self-assembled structure. In order to confirm this interpretation, Tunnelling Atomic Force Microscopy (TUNA) analysis is performed. In particular, the topographic mapping of the local filler dispersion of the selected nanocomposites is carried out for supporting the DC electrical results.