Dual Action of Phase Separation and Mechanical Locking Enabled Low-Value Waste Wood Into High-Performance Structural Phase-Change-Induced Self-Healing Materials.

Abstract

Wood is used as a high-performance structural material in advanced buildings owing to its high mechanical strength, sustainability, and environmental friendliness. However, to overcome the intrinsic size limitation of natural wood, developing green adhesives with high strength, self-healing, recyclability, and low cost to replace polluting petroleum-based products has become the key objective for the next stage in wood adhesives research. Inspired by the multiscale structure of gecko toe pads, this work develops a biomimetic self-healing adhesive featuring dual mechanisms of phase separation and mechanical interlocking. By introducing sodium acetate trihydrate (SAT) into a poly(vinyl alcohol) (PVA)/wood powder (W) adhesive, phase separation occurs to promote the formation of a dense hydrogen-bonding network and a mechanically interlocked microstructure, which makes the green, sustainable PVA/W/SAT adhesive with high shear strength (5 MPa). Benefiting from SAT's excellent phase-change capability, the material achieves phase-change-induced self-healing at crack interfaces. The combination of superior mechanical performance, self-healing functionality, and environmental friendliness makes the PVA/W/SAT adhesive a promising candidate for transforming waste wood into high-performance planks, significantly reducing the carbon footprint of structural materials.