Ultrastrong and Transparent Wood Film Enabled by Interfacial Interlocking.

Developing high-performance biomass materials with excellent mechanical strength and recyclability is essential for addressing resource crises and environmental pressures. Natural wood possesses a highly oriented cellular framework that provides high load-bearing potential. However, the weak interfacial connections lead to limited mechanical performance, severely restricting its engineering applications. Herein, we proposed an interfacial interlocking strategy that converts natural wood veneer into an interfacial interlocking wood film (IIWF). By the introduction of homologous cellulose, continuous cross-scale connections are established between cell wall microfibrils, transforming the discrete interface regions into a synergistic load-bearing network. The resulting IIWF achieves a tensile strength of 731.2 MPa, excellent flexibility, and optical properties (transmittance 79.6%, haze 71.0%). This reconstruction strategy does not rely on heterogeneous reinforcing phases, maintaining material homology and environmental compatibility throughout the process. This study provides a new path for the development of renewable, high-strength, transparent materials, with a wide range of applications.