Molecular dynamics simulations of solvent-exfoliation and stabilization of graphene with the assistance of compressed carbon dioxide and pyrene–polyethylene glycol

Abstract

In this work we carried out molecular dynamics (MD) simulations to explore the mechanism of solvent-exfoliation and stabilization of graphene in the presence of (compressed) carbon dioxide (cpCO₂), p-xylene and pyrene–polyethylene glycol (Py–PEG) polymers. We studied the role of each component in graphene exfoliation and stabilization by setting different experimental variables. The simulation results show that the cpCO₂ molecules played a “wedge” role in the exfoliation process, firstly wedging into the interlayer, and then helping solvent molecules to insert into the interlayer. The solvent molecules between the graphene sheets are the main reasons that graphene exfoliation is achieved. And the Py–PEG polymer chains mainly act as stabilizers to prevent the exfoliated graphene sheets from restacking. This work provides detailed theoretical clues to better understand the mechanism of exfoliation and stabilization of graphene.