Esfoliação e funcionalização de nanofolhas de MoS2: desenvolvimento de novos materiais elastoméricos

Abstract

Two-dimensional materials, such as MoS2, have been extensively studied in recent decades due to their excellent properties in electronics, electrocatalysis, optics and mechanics. A major focus in recent research resides in the surface modification of the MoS2 structure through covalent or non-covalent functionalization for the development of new functional materials. Within this perspective, this work initially presents a simple approach of liquid phase exfoliation, assisted by an ultrasound bath, to exfoliate and functionalize, in a single step, MoS2 dispersed in a polybutadiene (PB) solution forming functionalized nanosheets (f-MoS2). In the synthesis step, the influence of the synthesis temperature on the concentration of functionalized PB was verified. Then, the functionalized nanosheets were incorporated at different loadings in a PB matrix and subsequently vulcanized only with sulfur. The elastomeric nanocomposites (f-MoS2/PB) were subjected to mechanical tests to evaluate the influence of f-MoS2 on mechanical properties such as Young's modulus and elongation at break. In addition, the rubber nanocomposites were also submitted to swelling tests in MEK and toluene and compared with the swelling of traditional rubbers (nitrile and fluorinated). Hence, the set of results allows us to conclude that it is possible to control the concentration of functionalized PB in MoS2 nanosheets by varying the ultrasound synthesis temperature. The f-MoS2 nanosheets promote a significant mechanical improvement in which it is possible to control the Young's modulus and the elongation at break of nanocomposites. Furthermore, there is a notable reduction in the swelling-ratio in MEK and toluene with the addition of f-MoS2 which can be even compared to traditional nitrile and fluorinated rubbers. The statistical results showcase that it is possible to modulate the swelling-ratio of the elastomers by varying the concentration of f-MoS2 or its synthesis temperature.