Interface Strengthening of Brittle AgNW-MXene Composite Films through PVA or WPU Polymers for Flexible...

In electromagnetic interference (EMI) shielding applications, high shielding effectiveness and good mechanical properties are extensively required considering conformal or foldable use. However, the natural brittleness of efficient shielding materials like layered structure hinders their widespread application and mechanisms behind these fragile films need in-depth study. Herein, silver nanowire-transition metal carbide nanosheet composite films with 63.93 dB under 4.02 μm are first prepared through mass ratio optimization. Polymers incorporated into the brittle nanowire-nanosheet system are designed through simultaneous positive pressure filtration with nanowires and nanosheets. It further increases the shielding effectiveness owing to impedance matching through conductivity adjustment; more importantly, the flexibility and property stability of films are significantly enhanced to withstand 3000 bending cycles, maintaining values of 58.81 and 63.00 dB for nanowire-nanosheet/poly(vinyl alcohol) and nanowire-nanosheet/waterborne polyurethane, respectively. Next, mechanisms of interface strengthening through polymer incorporation are thoroughly investigated through in-depth Fourier transform infrared and X-ray photoelectron spectroscopy analysis, cross-link density tests, as well as microstructure characterization. Polymers synergistically strengthen the microscopic interface through hydrogen-bond network formation and chain segment motion, providing elastic recovery properties. This work provides a viable strategy to design and fabricate flexible, lightweight, and high-performance shielding materials for many advanced fields.