Exfoliation of graphite to few-layer graphene in aqueous media with vinylimidazole-based polymer as high-performance stabilizer

Abstract

Viability and future of graphene depends, to a great extent, on the availability of such a method that can mass produce high-quality graphene in an affordably way. In this connection, liquid-phase exfoliation of graphite to produce few-layer graphene (FLG) has proven a competitive solution; whereas application of polymeric stabilizer is an effective measure to enable such a task performed in the interested liquid such as water. With this in mind, four vinylimidazole (VI)-based polymers with different pendent groups have been designed, synthesized, and tested as stabilizers for FLG exfoliation in aqueous media. The exfoliation process is studied as functions of VI-polymer molecular structure, polymer concentration, and initial graphite concentration. Under assistance of VI-polymers, stable aqueous FLG dispersions form in situ, with the concentration up to 3.25 mg mL−1, the FLG-to-stabilizer ratio as large as 11.7, and 88% of dispersed flakes having fewer than five layers. The experimental results also show the VI-polymer exfoliated FLG to be of high quality with few defects, high electrical conductivity, and low cytotoxicity. The ready dispersion thus paves the way for various applications such as in the biomedical and electronic fields. Finally, as an application demonstration, a simple FLG-based sensor is fabricated for chemical vapor sensing.