Surface Tension Components Ratio: An Efficient Parameter for Direct Liquid Phase Exfoliation.

Direct liquid phase exfoliation (LPE) is generally regarded as an effective and efficient methodology for preparing single- to few-layered nanosheets on a large scale. Based on a previous finding that the polar and dispersive components of surface tension can be used as critical parameters for screening suitable solvents for LPE, in this study, we conducted in-depth research on direct LPE of two-dimensional (2D) materials by the extensive LPE of a series of 2D materials and the thorough comparison of their surfaces properties and LPE efficiencies. We rationally developed the surface tension component matching (STCM) theory, and in nature, its key point lies in the close ratio of polar to dispersive components (P/D) between the solvents and the aimed 2D materials. To this end, the surface tension components ratio is demonstrated to be an effective parameter for screening LPE solvents. In addition to the optimization of the LPE process for these 2D materials, this work has further greatly enlarged the comprehensive library for the solvent and 2D material matching pairs based on the improved STCM theory.