Biomimetic mineralization strategy enables high-strength and water-resistance magnesium oxychloride cement-based inorganic adhesives

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Inorganic adhesives with high bonding strength and flame resistance hold great promise for applications in manufacturing and construction. However, conventional inorganic adhesives typically suffer from poor interfacial compatibility and insufficient toughness, which substantially restricts their practical utility. Herein, inspired by coral skeleton mineralization, we design a novel organic-inorganic hybrid adhesive based on a magnesium oxychloride cement (MOC) matrix synergistically reinforced by a three-dimensional noncovalent network formed with sodium alginate (SA), poly(acrylic acid) (PAA), and citric acid (CA). Through the combined effects of hydrogen-bond crosslinking, chelation confinement, and mineralization templating, the resulting adhesive exhibits significantly improved water stability, robust adhesion strength, and enhanced toughness. Molecular dynamics simulations reveal strong interpolymer interactions and dense self-assembled clusters that serve as confined structure for hydration and crystal growth. With this strategy, the modified MOC/PAA/SA2 adhesive achieves a softening coefficient of 0.97 and a wet bonding strength of 2.48 MPa, representing increases of 212.9% and 68.7% relative to pure MOC, respectively. Furthermore, the MOC/PAA/SA2 adhesive delivers a debonding work of 1477.5 mJ, which is 210.3% higher than that of pure MOC. This innovative strategy, leveraging biomimetic mineralization to alter inorganic hydration reactions, benefits the future design of MOC-based and other inorganic adhesive with improved mechanical integrity and durability.