Improved dielectric properties of polyetherimide and polyaniline-coated few-layer graphene based nanocomposites

Abstract

The dispersion of various nanofillers in the polymer matrix is a challenging problem, which limits their potential use. To overcome this problem, few-layer graphene was grafted with polyaniline to improve its dispersion in the polymer matrix. In this work, a methodology to improve the properties of polyetherimide composites with few-layer graphene grafted with polyaniline is proposed. First, few-layer graphene (FLG) was exfoliated by liquid phase exfoliation by using N-methyl-2-pyrrolidone (NMP) as a solvent. For creating defects on the surface of graphene sheets, they were treated with nitric acid. The acid treated few-layer graphene was grafted by the polyaniline (PANI) by the in-situ polymerization method. The concentration of FLG with polyaniline was varied from 0 to 5 wt%. The polyaniline grafted few-layer graphene (PANI-g-FLG) samples were then blended with polyetherimide. The composite systems displayed an insulator-to-conductor percolating transition as the filler loading increased, and the percolation thresholds were estimated to be 1.5 wt% of the FLG loading. The structural features and morphology of PANI, PANI-g-FLG, and nanocomposites were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanical properties of composites were studied by universal testing machine. The tensile strength was also improved significantly up to 57% in the three-component hybrid system as compared to PEI. Similarly, the AC conductivity of PEI has also increased seven orders of magnitude from 1.47 × 10−9 to 5.91 × 10−2 S cm−1 (at 100 HZ) in the hybrid nanocomposites by adding PANI-g-FLG containing 1.5% FLG. The dielectric constant of the PEI increased from 2.73 × 100 to 3.72 × 105 for nanocomposites at the frequency of 100 Hz. This work provides a potential design strategy for brilliant performance flexible dielectric graphene-based polymeric material.