Effect of pyrene treatment on the properties of graphene/epoxy nanocomposites

Abstract

Graphene is a two-dimensional nanocarbon that is currently being investigated for applications in a variety of areas. Graphene has unusual properties including a large surface area of 2,600 m·g, high thermal conductivity of ~3,000 W m·K, high electrical conductivity of ~550 S·cm, a high modulus of ~1 TPa, and a high aspect ratio of several hundreds. Aksay et al. recently reported that graphene sheets can be produced in bulk by the thermal expansion of sufficiently oxidized graphite oxide (GO). These exfoliated sheets are called functionalized graphene sheets (FGSs) because some of the oxygen containing groups such as epoxy groups remain after thermal treatment. FGSs have an affinity for polar solvents and polymers, as well as have a high electrical conductivity of about 10 S·cm. Polymers such as epoxy resin are generally good electrical insulators. However, an improvement in electric conductivity is necessary for applications that require electrostatic dissipation or electromagnetic radiation shielding. Nanocarbons with high conductivity and a large aspect ratio can be effectively utilized in the preparation of conductive polymer nanocomposites. Recent studies have demonstrated the emergence of FGS as fascinating conductive nanofillers with low percolation thresholds. In nanocomposites, nanofiller dispersion and interfacial interactions with the matrix polymer can be significantly enhanced through chemical or non-covalent physical modification of the nanofiller surface character. Many researchers have reported that polycyclic aromatic hydrocarbons such as pyrene or perylene are strongly adsorbed onto graphene sheets or carbon nanotubes through π-π interactions. We observed that the dispersibility of FGSs in the epoxy resin matrix was improved when the FGSs were treated with pyrene. This paper describes the effect of pyrene treatment on the dispersion, electric, and rheological properties of FGS/epoxy nanocomposites.