Ionizable Star Copolymer-Assisted Graphene Phase Transfer between Immiscible Liquids: Organic Solvent/Water/Ionic...

The present study reports on the development of a simple two-step process toward the isolation of nearly defect-free mono- and few-layer graphenes in various media. This was achieved by liquid phase pre-exfoliation of pristine graphite in the presence of an ionizable PSP2VP heteroarm star copolymer in an organic solvent and subsequent graphene shuttle between immiscible media, that is, organic solvent/water and water/ionic liquid. This polymer-assisted phase transfer of graphene sheets gave rise to enrichment of suspended nanostructures in monolayers, especially in an aqueous environment. The exfoliation efficiency was assessed through Raman and electron microscopy. Relatively high concentration suspensions of efficiently exfoliated graphene sheets of large size and in high solubilization yield, could be prepared in any kind of solvent, that is, organic low boiling point medium, aqueous environment, or ionic liquid, whereas the shuttle transfer was found to be a reversible process between organic and aqueous phases.