A high-strength bonding, water-resistance, flame-retardant magnesium oxychloride cement based inorganic adhesive via the construction of supramolecular system

Magnesium oxychloride cement (MOC) adhesive has the advantages of being non-formaldehyde and flame retardant and having low energy consumption; however, its poor compatibility with the wood interface results in low bonding strength. Inspired by the H-bonded β-sheets nanoconfinement phase of spider silk, a high-performance inorganic adhesive was developed based on the supramolecular network system of poly (vinyl alcohol)/phytic acid (PVA/PA) with dissolved ions and the synchronous hydration process of MOC. Benefiting from the H-bond crosslinking and chelation confinement effects, the addition of PVA/PA enables MOC to penetrate steadily into the wood. Under this strategy, the compressive strength and softening coefficient of the modified MOC adhesive were 65.07 MPa and 0.84, which were 17.03% and 425% higher than the unmodified MOC adhesive, respectively. In addition, the MOC/PVA/PA adhesive achieved a wet shear strength of 2.02 MPa, 68.3% higher than that of the MOC adhesive. These results demonstrate that the MOC/PVA/PA adhesive would be a promising inorganic adhesive in wood-based building materials.