White coloring and superhydrophobic modification of wood via LDHs in-situ formation

Color regulation treatment represents a significant approach to enhance the value-added potential of fast-growing plantation wood, offering a promising pathway to alleviate the timber supply-demand imbalance. However, conventional wood dyeing methods often suffer from environmental pollution issues. Consequently, the development of a simple, efficient, and green color regulation strategy remains a considerable challenge. Starting from the perspective of overcoming the compatibility barrier between wood and intensely colored hydroxides, this study employs a metal-organic framework (MOF) as a sacrificial template. Utilizing an ultralow-concentration Zn 2+ salt solution (0.016 mol/L), hydrolysis and ion-exchange reactions were induced on the poplar wood surface. This process facilitated the in situ self-assembly of layered double hydroxides (LDHs), resulting in a desirable white coloration (L* = 83.04, a* = 1.08, b* = 4.5). Furthermore, capitalizing on the inherent surface roughness of the LDHs and leveraging the unique anion-exchange capability of their interlayer galleries, hydrophobic long-chain molecules were incorporated. This integration conferred superhydrophobic properties to the white-dyed wood, achieving a water contact angle of 153.2 °. This method not only successfully addresses the compatibility issue between wood and hydroxides for effective coloration but also endows the dyed wood with excellent resistance to UV aging (after 120 h of accelerated UV aging, its color difference ΔE*=9.47, which reduces UV-induced discoloration by approximately 65.4 % compared to untreated wood), abrasion, water, and decay. This work provides a novel route for developing low-cost, environmentally friendly wood dyeing technologies. • Overcomes hydroxide-wood incompatibility barrier using sacrificial MOF template. • Ultralow Zn²⁺ (0.016 mol/L) achieves efficient wood whitening. • LDH’s high roughness and Sa’s low surface energy confer superhydrophobicity. • Whitened wood gains UV, abrasion, water, and decay resistance.