(498e) Molecular Dynamics Simulation-Based Study of MoS2 Solubilization: Predicting Solvent Performance in Liquid-Phase Exfoliation

Sresht, V. - Presenter, Massachusetts Institute of Technology
Blankschtein, D., Massachusetts Institute of Technology

The intense research focus on graphene has ignited interest in the investigation of other two-dimensional 'wonder' materials, many of which exhibit superior chemical and opto-electronic properties. Experimental characterization of 2D nanomaterials, such as MoS2, hBN, and WS2, offers tantalizing glimpses of future applications in high-performance sensors and transistors. However, the large-scale production of these layered materials presents a key impediment to commercialization. Although liquid-phase exfoliation provides a scalable manufacturing route for high-quality layers, precise guidelines for the selection of a good exfoliating agent for a given nanomaterial remain elusive.

With the above in mind, we have used molecular dynamics (MD) simulations to garner several insights into the organization of molecules of commonly employed solvents, including N-methylpyrrolidone (NMP), dimethylformamide (DMF), N,N’-dimethylsulphoxide (DMSO), Cyclohexyl-pyrrolidinone (CHP), N-vinyl-Pyrrolidinone (NVP), and water (H2O), around and in-between the MoS2 sheets. We focus on the correlations between the structural features of these solvents and their effect on the energy barrier hindering the aggregation of the MoS2 sheets. The combination of MD-based computation of the potential of mean force (PMF) between pairs of MoS2 sheets and the application of theories of colloid aggregation offer a detailed picture of the mechanics underlying the stability of MoS2 sheets in these popularly-employed solvents.

In this talk, we will present a theoretical framework that harnesses MD simulations and colloidal theories to predict and rank the relative dispersive capabilities of the solvents considered with respect to MoS2. The excellent agreement between the predicted and the experimentally-observed solvent efficacies enables us to suggest design principles to assist in the selection of solvents which are suitable for the liquid-phase exfoliation of MoS2.