Optimization of electrical conductivity in poly(2-ethylaniline)/graphene-based nanocomposites via response surface methodology and DFT-based computational ınvestigation

Abstract

Conductive reduced graphene oxide–poly(2-ethylaniline) (RGO-g-PEAn) and few-layer graphene–PEAn (FLG-g-PEAn) nanocomposites were synthesised via graphene-assisted in situ polymerisation of 2-ethylaniline. The reactive surfaces of RGO and FLG facilitated oxidant-free polymerisation, highlighting the active role of graphene nanosheets during polymerisation and in the formation of conductive percolation networks that enhance charge transport. In this study, response surface methodology (RSM) of the central composite design (CCD) was employed to optimise the effects of two variables on the electrical conductivity of the nanocomposites. The variables in question were polymerisation time (2–10 days) and graphene-based nanomaterial loading (20–100 mg). RSM ascertained the optimum conditions in terms of polymerisation time and graphene loading: 4.353 days and 91.812 mg RGO for RGO-g-PEAn, and 5.548 days and 92.291 mg FLG for FLG-g-PEAn. Morphological analysis by transmission electron microscopy (TEM) revealed interfacial interactions between PEAn chains and graphene surfaces and the formation of interconnected conductive networks in the nanocomposites. RGO-g-PEAn and FLG-g-PEAn exhibited RSM-predicted electrical conductivities of 4.32 × 10⁻¹ and 1.764 S cm⁻¹, respectively, which were approximately six orders of magnitude higher than that of pristine PEAn (5.29 × 10⁻⁷ S cm⁻¹) at the optimum conditions. Furthermore, density functional theory (DFT) calculations were performed to investigate the charge transfer capabilities of the synthesised composites, providing theoretical support for the experimentally observed structure–property relationships. The findings of this study demonstrate that a combination of graphene-assisted oxidant-free polymerisation, together with RSM optimisation and DFT analysis, provides an effective strategy for developing conductive PEAn/graphene nanocomposites for electronic applications.