Exfoliation/dispersion of low-temperature expandable graphite in nanocellulose matrix by wet co-milling

Viability and future of graphene depends, to a great extent, on a methodology that can mass-produce high-quality graphene in an affordable way. In this work, wet co-milling of low-temperature expandable graphite (LTEG) with bamboo cellulose fibers through a grinder was proved to be a scalable and environmentally friendly approach for the exfoliation/dispersion of graphene-like carbon in an aqueous suspension in which the mechanically isolated cellulose nanofibers (CNFs) acted as a "green" dispersant. The exfoliation/dispersion degree of LTEG was studied as a function of passing times through the grinder. Under the assistance of CNFs, stable aqueous dispersions of CNFs/few-layer graphene (FLG) were obtained. Based on the CNFs/FLG dispersions, a series of nanocomposite films with high mechanical strength and excellent flexibility were fabricated. The tensile strength, Young's modulus, and elongation at break of the CNFs/FLG nanocomposite film were enhanced to 59.14MPa, 4.13GPa and 4.17% respectively after 100 passing times through the grinder. However, with the passing time increased, the electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) decreased, in agreement with the good dispersion of FLG in CNFs matrix. The strategy proposed here is simple, highly efficient, and low in cost, exhibiting great potential for producing exfoliated FLG with few defects at an industrial scale.