Micro-nanocomposite films with enhanced mechanical and barrier properties by non-destructive exfoliation and self-assembly of MXene/polyamide 6

The inferior dispersibility and poor interfacial interaction with the matrix substantially restricted the reinforcing effects of two-dimensional (2D) nanosheets on the composites. Here, large-sized and ultrathin LiHL-Ti 3 C 2 T x (LiHL-MXene) nanoflakes were successfully prepared by an organic solvent-assisted intercalation strategy, which effectively prevented fragmentation of nanoflakes without ultrasonic process under the advantage of low energy consumption. According to thermal stress induction, MXene nanoflakes were uniformly assembled within the polyamide 6 (PA6) matrix to construct a robust brick-and-mortar interface structure, thereby achieving reinforcement across multiple length scales. Benefiting from the homogeneous distribution of nanoflakes and strong filler-matrix interfacial interactions, the tensile strength and toughness of PA6/LiHL-MXene composites reached 67.81 MPa and 130.86 MJ/m 3 . By introducing the finite element representative volume elements (RVEs), stress–strain curves of uniaxial tensile testing were simulated and the coupling mechanisms between microstructure and mechanical behaviors were explored. High orientation and large contact area of LiHL-MXene effectively hindered the diffusion of gases to endow the composites with excellent barrier properties (oxygen permeability coefficient: 0.87 × 10 –17 mol·m/m 2 ·s·Pa; hydrogen permeability coefficient: 0.75 × 10 –16 mol·m/m 2 ·s·Pa). This work provided a feasible approach for developing next-generation high-performance barrier films, demonstrating applications in the fields of storage and transportation of gases.