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

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 Ti3C2Tx 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.