Preparation and properties of a novel graphene fluoroxide/polyimide nanocomposite film with a low dielectric constant

Abstract

This paper introduces an effective approach to fabricate novel graphene/polyimide nanocomposite films with a low dielectric constant. Graphene fluoroxide (GFO) nanosheets were produced through the exfoliation of graphite fluoroxide (GiFO) in N-methyl-2-pyrrolidone (NMP). GFO nanosheets reacted with 4,4′-diaminodiphenyl ether (ODA) to become ODA-functioned GFO (GFO-ODA) with amine end groups, which provided reactive sites for covalent bonding with PI chains. GFO-ODA/PI composite films were prepared via the thermal imidization of a GFO-ODA/PAA solution. In this composite, GFO-ODA nanosheets were chemically bonded to the PI matrix. The dielectric constant of the films depended on the loading of GFO-ODA and its minimum value reached 2.75 (at 10⁶ Hz) when the content of GFO-ODA was 1.0 wt%. Strong GFO-ODA nanosheets facilitate the load transfer and enhance the mechanical properties of PI films. GFO-ODA/PI film with 1.0 wt% loading had a Young's modulus ∼40% larger than pure PI film. In addition, the incorporation of GFO-ODA increased the glass transition temperature of the films and had no significant effect on the thermal stability.