High-concentration aqueous dispersions of graphene using nonionic, biocompatible block copolymers

The ability to disperse pristine graphene at high concentrations in aqueous solutions is an enabling step for large-scale processing and emerging biomedical applications. Herein we demonstrate that nonionic, biocompatible block copolymers are able to produce graphene dispersions with concentrations exceeding 0.07 mg mL^-1 via sonication and centrifugation, resulting in optical densities above 4 OD cm^-1 in the visible and near-infrared regions of the electromagnetic spectrum. The dispersion efficiency of graphene using Pluronic and Tetronic block copolymers varies substantially depending on the lengths of their hydrophilic and hydrophobic domains, with the best of these copolymers sharing similar domain molecular weight ratios and comparable overall molecular weights. This study presents a new class of biocompatible dispersing agents for graphene in aqueous solution, thus suggesting a facile route to employ graphene in biomedical sensing, imaging, and therapeutic applications.