A high-performance magnesium oxychloride cement-based wood adhesive inspired by the mechanism of bone mineralization

The development of inorganic adhesives can effectively break away from fossil dependence and formaldehyde emissions issues of traditional synthetic resin adhesives. However, achieving both high mechanical strength and good water resistance in magnesium oxychloride cement (MOC) remains challenging. Herein, we present an efficient biomimetic mineralization approach to fabricate a high-strength and water-resistant MOC-based adhesive. Specifically, polyamide polyamine compound (PPC) served as an organic template, facilitating the formation of densely interwoven phase 5 crystals within its polymer network. Sodium citrate (SC) regulated the formation of phase 5 hydration products via Mg 2+ chelation. The synergistic interaction between PPC and SC promoted the development of a compact organic-inorganic hybrid structure within the MOC adhesive, thereby enhancing its mechanical properties, bonding performance, and water resistance. The findings indicated that the MOC-SC-PPC adhesive exhibited significantly enhanced properties. Among the formulations, the MOC-SC-PPC/0.8 adhesive exhibited the highest compressive strength of 36.19 MPa after 7 days of curing, while the MOC-SC-PPC/0.2 adhesive achieved the highest softening coefficient of 0.86, indicating substantially improved water resistance. Moreover, the modified adhesive exhibited a prolonged setting time (from 108 min to 269 min), which is beneficial for practical construction applications. The MOC-SC-PPC/0.6 adhesive exhibited significantly improved wet bonding strength (0.85 MPa vs. 0.61 MPa) compared to the pure MOC adhesive, indicating enhanced water resistance and interfacial bonding performance. This study provides a novel approach for fabricating a formaldehyde-free adhesive via a biomimetic mineralization strategy, which enhances the adhesive’s applicability in humid environments and exerts a positive effect on sustainable resource utilization.