High-concentration aliphatic and aromatic dispersions of single- and few-layer graphene noncovalently modified by block copolymer crystallization

Pristine graphene flakes, with ∼12% monolayers, are directly exfoliated from natural graphite, and noncovalently modified by an amorphous–crystalline block copolymer, polyvinylcyclohexane-b-polyethylene-b-polyvinylcyclohexane (PVCH-b-PE-b-PVCH). The PE block selectively crystallizes on the graphene surface, while the PVCH block extends freely and stabilizes the graphene flakes in the aliphatic and aromatic solvents, which are generally viewed as nonsolvents for graphene. The rational solubility of the graphene flakes in these low-boiling-point solvents facilitates their solution-phase processing. After vacuum filtration, a freestanding graphene film with excellent electrical and mechanical properties is obtained, which can meet the requirements of large-area graphene-based thin-film devices.