Figure 1. Liquid phase exfoliation of TMDs with end-functionalized polymers.

Schematic representation of the proposed mechanism for the exfoliation of various TMDs using different types of amine-terminated end-functionalized polymers in organic solvents. Hexagonal layers of transition metal atoms (M) sandwiched between two layers of chalcogenides (X) are represented by a stoichiometry of MX₂ by the yellow and grey spheres, respectively. The amine-terminated polymers are simplified for clarity. Interaction between the lone electron pairs of nitrogen atoms and the electron-accepting metal atoms weakens the self layer–layer attraction and the polymer chains provide further separation between the layers, thereby ensuring good exfoliation and dispersion. FT-IR spectra of MoSe₂, PS-NH₂ and MoSe₂-PS-NH₂ are shown. Few-layer MoSe₂ and MoS₂ nanosheets dispersed on the 2-l scale are apparent in the photographs (Scale bar, 5 cm).