Ethylenediaminetetraacetic acid-mediated structural enhancement and interfacial stabilization for high-performance...

The practicality of bio-based adhesives is often limited by insufficient mechanical strength and poor environmental stability. Herein, a coordination-crosslinked starch adhesive (S-Ca-EDTA) was developed through the mediation of ethylenediaminetetraacetic acid (EDTA) and Ca²⁺. EDTA first coordinates with Ca²⁺ to generate metal-ligand coordination nodes, while the carboxyl groups of EDTA can also react with hydroxyl groups on starch chains through esterification during curing. These coordination interactions and covalent ester linkages jointly construct an organic-inorganic hybrid network. As a result, the bonding strength, water resistance, and environmental stability of the adhesive were enhanced significantly. Compared to starch adhesive, the shear strength of S-Ca-EDTA adhesive was increased by 180%. Furthermore, the S-Ca-EDTA adhesive still exhibits excellent bonding performance after prolonged exposure to high temperatures (160-196 °C) and harsh chemical environments (pH 2-13). The synergistic antibacterial properties of EDTA and calcium sulfate not only provide excellent storage stability, but the adhesive also remains free of mold after 30 days of storage. Additionally, the adhesives exhibited reduced selected environmental impacts relative to traditional wood adhesives, thereby enhancing their sustainability potential. This research illustrates coordination-induced network engineering as a viable approach for enhancing high-performance carbohydrate-based adhesive systems.