Hyperbranched catechol biomineralization for preparing super antibacterial and fire-resistant soybean protein adhesives with long-term adhesion

Developing a strong soybean protein adhesive with long-term adhesion and multiple functions to replace petroleum-based adhesives is important but challenging. Inspired by the biomineralization strategy, soybean protein as a matrix, 4-carboxyphenylboronic acid as a crosslinker, a self-synthesized hyperbranched catechol polymer (DBA@HBPA) as a catechol group donor, and AgNO 3 as an Ag + donor were used to develop a strong and multifunctional soybean protein adhesive. The results showed that the coating and prepressing performance of the adhesive was improved by the addition of DBA@HBPA. The prepressing intensity of the adhesive improved by 156% and reached 0.89 MPa. Benefiting from the dynamic balance of quinone-catechol produced by Ag NPs and the super antimildew and antibacterial properties of Ag NPs and boron, the adhesive exhibited long-term adhesion behavior (pot life of 12 d), excellent mildew resistance (30 d), and antibacterial properties (colony count of 0). The wet shear strength of plywood prepared by the resultant adhesive was 1.28 MPa, which was 106% higher than that of the SPI adhesive. In addition, the resultant adhesive exhibited fire retardancy (LOI = 37.4%) and low VOCs emission (4.26*10 6 mg/m 2 ·h). This biomimetic design provides a novel and efficient strategy for the preparation of high-adhesion, multifunctional biomass composite adhesives.