Single step exfoliation and functionalization of MoS₂

Full text: Two-dimensional (2D) materials have attracted much attention from the scientific community due to their unique properties. 2D-MoS2 is highlighted as a great candidate for nanofiller in polymeric composites, due to its high Young's modulus (>270 GPa). However, although 2D composite materials can be applied in many fields, the quality and the yield of their fabrication process are a constant concern. MoS2 is the most studied transition metal dichalcogenide in the world and many techniques have been developed to obtain this material, such as chemical vapor deposition and mechanical exfoliation. Recently, liquid exfoliation using ultrasonication has been used to obtain MoS2 sheets and functionalized MoS2 sheets in a single step.1 The exfoliation in the presence of the polymer polybutadiene (PB) increases the yield of the process, since the PB bonds in the edge of the MoS2 sheets stabilize the 2D structure during the exfoliation. Accordingly, in this study we provide some fundamental insights into MoS2 exfoliation process. For this, 2D-MoS2 materials were prepared by exfoliation under ultrasonication by using a bath and a tip, with three different molar mass of PB (5k (PB5k), 200k (PB200k) and 200k-300k (PB300k)) and two different solvents to disperse the polymers (toluene and tetrahydrofuran). Characterizations of the 2D-MoS2 materials by X-ray and electron diffraction showed a higher degree of exfoliation in the presence of the polymer than in its absence. Besides, although the nature of the used solvents to disperse the polymer did not influence the quality of the sheets, the yield of the process was quite enhanced when toluene was used (11.26 % for the exfoliation when PB200k was used). This methodology provides a promising avenue toward the producing 2D-MoS2 composites with high degree of exfoliation and yield. (author)