High-throughput, direct exfoliation of graphite to graphenevia a cooperation of supercritical CO2 and pyrene-polymers

Abstract

A facile and green approach has been developed using supercritical CO₂ as penetrant, expanding agent and antisolvent, and pyrene-polymers as a molecular wedge and modifier, leading to high-throughput graphene dispersions. Herein, two specially designed pyrene-polymers with a large planar aromatic group and two substituted polymer dangling chains have been employed to stabilize the graphene sheets, which show excellent solubility in aqueous and organic solvents. The morphology and quality of the exfoliated graphene sheets are studied by transmission electron microscope (TEM), atomic force microscopy (AFM), Raman, FTIR, and wide-scanning X-ray photoelectron spectroscopy (XPS), which reveal that large scale and high quality graphene flakes are obtained by the facile process. The supercritical CO₂, pyrene-polymers and the solvent system have a significant influence on the exfoliation results. The pyrene-polymers attached to the graphene can further integrate graphene with other polymers to form new functional nanocomposites. This solution-based method combines high-throughput production and functionalization of graphene in one step, providing nanoscale building blocks for practical applications.