Graphene in Mixed Solvents: A Path towards Graphene Films,Emulsions and Foams

摘要

Applications requiring pristine graphene derived from graphite demand a solution stabilization method that utilizes an easily removable media.We use large scale atomistic molecular dynamics simulations to demonstrate solubilization/stability of pristine graphene sheets in mixed solvents.In particular,we have performed simulations of exfoliated graphene sheets in two immiscible solvents such as water and oil(heptane and styrene).These simulations have shown that exfoliated graphene sheets are captured by the water/oil interface,demonstrating properties expected for surfactants.Graphene layers localized at the interface are capable of restacking,forming an interface covering graphitic skin.Graphene stacks are located at the water/oil interface with slight preference towards the oil phase.We used potential of the mean force calculations to evaluate the strength of attraction between graphene and the water/oil interface.The surface activity of graphene was confirmed experimentally by formation of stable water-in-oil emulsions stabilized by graphitic skin formed at the water/oil interface.Polymerization of the continuous styrene phase produced graphene infused polymer foams with remarkable conducting,mechanical and solvent selectivity properties.