A Dense Graphene Monolith With Poloxamer Prefunctionalization Enabling Aqueous Redispersion To Obtain Solubilized Graphene Sheets

The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications. However, the tap density of commercial graphene powder is quite low (0.03-0.1 kg/m(3)), meaning that 1 kg graphene powder occupies about 10-30 m(3) in volume during transportation. And, the available content of commercial graphene dispersion/slurry in aqueous medium cannot exceed 5 wt%, although the density is high (approximate to 1050 kg/m(3)). In this work, a graphene monolith was prepared by oven-drying of graphene sheets prefunctionalized with poloxamer surfactants. Our graphene monoliths not only have a high density (1500 kg/m(3)) and high graphene content (approximate to 10 wt%), but also a full capability to be completely redispersed (approximate to 100%) in water by bath sonication to obtain solubilized graphene sheets, whose lateral size and thickness are unchanged compared to as-exfoliated ones. Moreover, a simple empirical method was proposed to predict the redispersion capability of graphene monoliths using different poloxamers by contact angle measurements. Our results provide a universal approach to make exfoliated graphene-based products with better downstream availability and lower transportation cost. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.