Facile fabrication of poly (tetrafluoroethylene)/graphene nanocomposite via electrostatic self-assembly approach

Dispersion of graphene nanosheets (GNs) in a polymer matrix as mono layers was an important step towards fabricating high performance polymer/GNs nanocomposites. However, the insoluble and infusible properties of poly (tetrafluoroethylene) (PTFE) made the incorporation of nanofillers in PTFE matrix difficult. In this paper, a novel method based on poly (tetrafluoroethylene) (PTFE) latex that assured the fine dispersion of GNs in PTFE matrix was developed. PTFE latex was first modified by polyethylenimine (PEI) to create the positive charges on the surface of the PTFE particles, and then assembled with negatively charged graphene oxide sheets directly in water through electrostatic interaction, followed with chemical reduction, cold briquetting and hot sintering. Nanocomposites with controllable content and uniformly distributed GNs in PTFE matrix were prepared. The electrostatic coupling interactions improved the dispersion of GNs and facilitated the formation of filler networks in the PTFE matrix. Both the mechanical and wear performance of PTFE/GNs nanocomposites were greatly improved. PTFE/GNs nanocomposites also exhibited excellent electrical properties with a percolation threshold as low as 0.5 wt% and an electrical conductivity of 1.4 S/m at only 2 wt% graphene loadings. The new method agrees well with the latex technical process in PTFE bulk industrial manufacture and paves the way for an environmentally benign process for the bulk production of high quality polymer-graphene nanocomposites.