Mechanics of MXene films: load transfer, sliding, and densification

Lamellar MXene films combine stiff two-dimensional platelets with mechanically active interfaces that govern load transfer, interlayer sliding, and failure. Here, a finite-overlap lamellar representative volume element is developed to describe the coupled effects of reversible interlayer shear transfer, irreversible sliding, and densification. The formulation introduces a film-scale effective interfacial stiffness, separated from microscopic interface properties through a dimensionless connectivity factor, χ. Finite platelet overlap determines the load-transfer efficiency, while an internal sliding variable distinguishes reversible deformation from irreversible interlayer motion and provides a common description of tensile loading and stress relaxation. The framework provides a mechanistic interpretation of the experimentally observed transition from CBM-III to CBM-IV, in which Young’s modulus increases from 21.5 to 25.0 GPa while tensile strength, failure strain, and toughness decrease. The model attributes this divergence to the competition between improved elastic load transfer and the increased propensity for interface-controlled sliding, while accounting separately for the loss of load-bearing capacity associated with porosity. Comparisons across hydrogen-bonded and sequentially bridged MXene architectures further examine the scope of this interpretation. The formulation is intended as a reduced-order mechanics framework for interpreting architecture-dependent trends, rather than as a calibrated predictor of ultimate strength, failure strain, or fracture toughness.