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• A biomimetic brush-like polymer with a catechol structure (ADD) was designed and developed. • The Ca 3 (PO 4) 2 was deposited on soy flour and mixed with ADD to develop a biomineralized adhesive. • The dry and wet shear strength of resultant plywood increased by 118.8% and 750%, respectively. • The adhesive has outstanding coating performance, mildew resistance, flame retardancy. The development of a formaldehyde-free soy flour adhesive with good coating ability, mildew resistance, and flame retardancy while maintaining high bond strength, is urgent but presents a challenge. Inspired by the strong adhesive performance derived from the brush-like structure of gecko toes, a brush-like polymer with a catechol group was synthesized to improve the adhesive behavior of soy flour adhesives. Prompted by the high strength derived from the biomineralized structure of oysters, Ca 3 (PO 4) 2 was sedimented on soy protein and combined with the brush-like polymer to construct a biomineralized structure, which endowed the resultant adhesive with mildew resistance and flame retardancy while maintaining high bond strength. The dry and wet shear strengths of the bonded plywood by the resultant adhesive increased by 118.8 % and 750 % relative to those of the unmodified adhesive. Moreover, the resultant adhesive possessed outstanding coating performance, superior mildew resistance (no mildew for 7 d), and high toughness (4.05 J of the work of adhesion). The limiting oxygen index of the resultant adhesive was increased from 26.4 % to 30.1 %. Thus, developing a system combined with a bioinspired biomineralized strategy and a brush-like polymer can potentially offer a template for the fabrication of hydrogels, functionalized surfaces, and composite materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hyperbranched catechol polymers (DBA@HBPA) was synthesized to mineralize Ag+. • The reaction among CPBA, SPI, and DBA@HBPA built a water-resistant cross-linking network. • The adhesive with anti-mildew/anti-bacterial properties had a long-term adhesion for 12 d. • The adhesive has high bond strength, good toughness, fire resistance and low VOCs emission. 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*106 mg/m2·h). This biomimetic design provides a novel and efficient strategy for the preparation of high-adhesion, multifunctional biomass composite adhesives. [ABSTRACT FROM AUTHOR]

[Display omitted] • The nanophase-reinforced organic–inorganic hybrid structure was successful constructed. • Using PA as crosslink agent instead of traditional epoxide linked SPI and G-co-Q hybrid. • The resultant adhesive has a high performance with excellent flame-retardant, mildew resistance and antibacterial. • The wet shear strength of the resultant plywood increased by 78.7% to 1.09 MPa. • The plywood bonded by our adhesive is the absorption dominated EMI shielding material with low reflection characteristics. The development of multifunctional adhesive with high bond strength, toughness, mildew resistance, antibacterial properties, flame retardancy, and electromagnetic (EMI) shielding properties has drawn interest and simultaneously presents a challenge in the wood panel industry. Herein, inspired by the organic–inorganic hybrid structure of oysters, an antibacterial agent quaternary ammonium salted hyperbranched polyamide (QHBPA), was synthesized to modify graphene nanosheets (GNSs) via cation-π interaction, eventually forming a G-co-Q hybrid. The G-co-Q hybrid was then combined with soy protein isolate (SPI) and phytic acid (PA) to develop a plywood adhesive with an organic–inorganic hybrid structure via electrostatic interactions and hydrogen bonds. The resultant adhesive exhibited good mildew resistance and antibacterial activity (144 h shelf life). Compared with the SPI adhesive, the dry and wet shear strengths of the plywood with the SPI/PA/G-co-Q adhesive increased by 76.6% and 78.7%, respectively. Meanwhile, non-covalent cross-linking and the formation of an organic–inorganic hybrid structure endowed the adhesive with excellent toughness. Furthermore, the limiting oxygen index (LOI) of the resultant adhesive was 35.5%, reflecting an increase of 49.1% relative to that of the SPI adhesive, indicating that the adhesive possesses superior flame retardancy. Importantly, owing to its unique isolated multilayered structure, the plywood bonded by our adhesive is an absorption dominated EMI shielding material with low reflection characteristics and displays a desirable EMI shielding effectiveness of 43 dB. Therefore, this study provides a creative insight into the design of high value-added and multifunctional plywood with promising application prospects not only in conventional wood-based panels but also in advanced EMI shielding materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SiO 2 nanohybrid (DP@SiO 2) was successful synthetized. • Using HCCP as crosslink agent instead of traditional epoxide linked SPI and DP@SiO 2. • The resultant adhesive has a high performance with excellent flame-retardant and coating ability. • The wet shear strength of the resultant plywood increased by 143% to 1.46 MPa. • The limiting oxygen index (LOI) of the resultant adhesive was as high as 39.4%. Developing an environment-friendly soy protein adhesive with high bonding strength and flame retardancy has drawn interest and simultaneously presented a challenge in the wood panel industry. Prompted by the organic–inorganic hybrid of oysters, this study proposes a nanohybrid (DP@SiO 2) consisting of the nano silica (SiO 2) and polyethyleneimine (PEI) via electrostatic interaction and grafting 3, 4-dihydroxybenzaldehyde (DBA) by Schiff base reaction. The obtained structure was then combined with a multifunctional cross-linker hexachlorocyclotriphosphazene (HCCP) and soy protein isolate (SPI) to develop a plywood adhesive. The resultant adhesive exhibited good coating ability and prepressing properties, which were attributable to the catechol groups of DP@SiO 2 and the reaction between protein and HCCP. Compared with that of the SPI adhesive, the prepressing strength of plywood with the SPI/HCCP/DP@SiO 2 adhesive was increased by 304%. The dry and wet shear strengths of the plywood adhesive were 110% and 143% higher than those of the SPI adhesive, respectively, which were attributable to the formation of the cross-linking and organic–inorganic hybrid structure, and improvement in adhesive toughness caused by the combination of covalent and multiple hydrogen bonds. The limiting oxygen index (LOI) of the resultant adhesive was 39.4%, reflecting an increase of 71% relative to that of the SPI adhesive, indicating that the adhesive has excellent flame retardancy. This efficient organic–inorganic hybrid strategy can promote the enhancement and functional modification of underwater adhesives, hydrogel, and composite materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SiO 2 nanohybrid (DP@SiO 2) was successful synthetized. • Using HCCP as crosslink agent instead of traditional epoxide linked SPI and DP@SiO 2. • The resultant adhesive has a high performance with excellent flame-retardant and coating ability. • The wet shear strength of the resultant plywood increased by 143% to 1.46 MPa. • The limiting oxygen index (LOI) of the resultant adhesive was as high as 39.4%. Developing an environment-friendly soy protein adhesive with high bonding strength and flame retardancy has drawn interest and simultaneously presented a challenge in the wood panel industry. Prompted by the organic–inorganic hybrid of oysters, this study proposes a nanohybrid (DP@SiO 2) consisting of the nano silica (SiO 2) and polyethyleneimine (PEI) via electrostatic interaction and grafting 3, 4-dihydroxybenzaldehyde (DBA) by Schiff base reaction. The obtained structure was then combined with a multifunctional cross-linker hexachlorocyclotriphosphazene (HCCP) and soy protein isolate (SPI) to develop a plywood adhesive. The resultant adhesive exhibited good coating ability and prepressing properties, which were attributable to the catechol groups of DP@SiO 2 and the reaction between protein and HCCP. Compared with that of the SPI adhesive, the prepressing strength of plywood with the SPI/HCCP/DP@SiO 2 adhesive was increased by 304%. The dry and wet shear strengths of the plywood adhesive were 110% and 143% higher than those of the SPI adhesive, respectively, which were attributable to the formation of the cross-linking and organic–inorganic hybrid structure, and improvement in adhesive toughness caused by the combination of covalent and multiple hydrogen bonds. The limiting oxygen index (LOI) of the resultant adhesive was 39.4%, reflecting an increase of 71% relative to that of the SPI adhesive, indicating that the adhesive has excellent flame retardancy. This efficient organic–inorganic hybrid strategy can promote the enhancement and functional modification of underwater adhesives, hydrogel, and composite materials. [ABSTRACT FROM AUTHOR]