Understanding significantly reinforced polymethyl methacrylate composites induced by two‐dimensional Ti _{n+ 1} C _n from an atomistic perspective

Abstract MXenes, which have good reinforcing and toughening effects, can serve as excellent polymer additives. However, the mechanism whereby MXenes act has not been revealed. In this study, to understand the reinforcement effect of Ti _n+1 C _n on polymethyl methacrylate (PMMA) from an atomistic perspective, we used molecular dynamics to conduct unidirectional tensile simulations of PMMA composites reinforced with monolayer Ti ₂ C and Ti ₃ C ₂ sheets. The results showed that Ti ₃ C ₂ can more significantly improve the mechanical properties of the PMMA polymer than Ti ₂ C, and the yield stress and Young's modulus of the Ti ₃ C ₂ /PMMA complexes were respectively 54.39% and 73.46% higher than the Ti ₂ C/PMMA complexes. To further reveal the interaction mechanism between Ti _n+1 C _n and PMMA, different separation speeds were used to simulate the pull‐out of Ti _n+1 C _n from the PMMA matrix. The results showed that, in addition to the enhancement of interfacial strength by non‐bonding van der Waals forces, there were TiO and CTi bonds between Ti _n+1 C _n and PMMA, which further increased the interfacial strength. Ti ₃ C ₂ formed a denser interfacial region with PMMA, it could more effectively resist the formation and expansion of cracks. These findings may provide an important theoretical basis to design new type of MXene/polymer composites with excellent mechanical properties. Highlights MXene greatly improved the mechanical properties of the PMMA matrix. Formation of chemical bonds improved connection between the MXene and PMMA. The addition of MXene slows down the rate of crack propagation in PMMA.