Unraveling the effects of surface functional groups and assembly orientations on the interfacial mechanics of MXene/Silk composites

Abstract

Interfacial regulation is the core and an urgent scientific issue for optimizing the performance of MXene-based biocomposites. This study uses all-atom molecular dynamics (AAMD) simulations to systematically investigate the coupling effects of Ti₃C₂T_x surface terminal groups (–O and –OH) and silk fibroin (SF) chain orientations (0°, 45°, and 90°) on the interfacial mechanical properties of MXene-based biocomposites. Equilibrium analysis demonstrates that the Ti₃C₂(OH)₂ terminal groups construct the strongest hydrogen bond network, yielding the maximum interfacial binding energy. Shear simulations reveal significant orientational differences in interfacial strength: the 0° orientation achieves the highest shear strength, confirming that ordered alignment is critical for efficient stress transfer. Dynamic analysis uncovers two distinct interfacial failure modes: the 0° orientation exhibits brittle-like interfacial fracture under high strength, while the 90° orientation undergoes ductile failure dominated by dynamic friction. The bulk structure of SF remains stable during force-based shear simulation, verifying that the reinforcement mechanism of MXenes originates from optimized interfacial load transfer. This work provides crucial atomic-scale guidance for the rational design and optimization of interfacial mechanical properties in MXene-based composites.