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Soybean meal (SM)-based adhesive can solve the issues of formaldehyde emission and over-reliance of aldehyde-based resins but suffers from poor water resistance, weak adhesion strength, and high brittleness. Herein, a high-performance adhesive inspired by lobster cuticular sclerotization was developed using catechol-rich condensed tannin-functionalized boron nitride nanosheets (CT@BNNSs), amino-containing chitosan (CS), and SM (CT@BNNSs/CS/SM). The oxidative crosslinking between the catechol and amino, initiated by oxygen at high temperatures, formed a strengthened and water-resistant interior network. These strong intermolecular interactions induced by phenol–amine synergy accompanied by the reinforcement of uniformly dispersed BNNSs improved the load transfer and energy dissipation capacity, endowing the adhesive with great cohesion strength. Given these synergistic effects, the biomimetic CT@BNNSs/CS/SM adhesive caused noticeable improvements in water tolerance, mechanical strength, and toughness over the neat SM adhesive, e.g., enhanced wet shear strength (1.46 vs. 0.66 MPa, respectively), boiling water shear strength (0.92 vs. 0.43 MPa, respectively), and debonding work (0.368 vs. 0.113 J, respectively). Thus, this study provided a green and low-cost bionic strategy for the preparation of high-performance biomass adhesives. • An advanced adhesive inspired by lobster cuticular sclerotization is reported. • Oxygen at high temperatures initiated the crosslinking between CT@BNNSs and CS/SM. • Such phenol–amine synergy endowed the adhesive with great cohesion strength. • Strong intermolecular interactions and BNNSs reinforcement improved the adhesive's toughness. [ABSTRACT FROM AUTHOR]

Exploring the reusability of wood-based panels is imperative in the wood industry for sustainable development and carbon balance. Non-reusable adhesives make wood-based panel recycling difficult. In this study, inspired by the adhesion and de-adhesion behavior of snail slime, we built dynamic covalent/hydrogen hybrid networks into adhesive system for achieving both high bonding performance and reusability. Specifically, the softwood lignin was purified and pretreated by ultrasonication to form a catechol structure (UAL) and then combined with soybean protein to develop a 100 % bio-based wood adhesive. The catechol structure of UAL formed dynamic covalent bonds (C N) with the amino groups of the protein to improve the water resistance and formed multiple hydrogen bonds as a sacrificial network to improve the toughness of the adhesive. Thus, the wet shear strength of plywood bonded by the resultant adhesive improved by 101.4 % to 1.37 MPa. The adhesive also exhibited flame retardancy (LOI = 37.7 %), mildew resistance (60 h), and antibacterial performance (inhibition zone = 8 mm). Notably, owing to the rearrangement of dynamic covalent/hydrogen hybrid networks and the thermoplastic property of UAL, the resultant adhesive was reusable (3 cycles) and degradable (2 months), which provides a potential method for the reuse of wood-based panels. • Ultrasonic treats lignin to form catechol structure (UAL) and combine with SPI to obtain adhesive. • Dynamic covalent/hydrogen hybrid networks were constructed in adhesive system. • The SPI/UAL adhesive has good coating, prepressing intension, and bonding performance. • The SPI/UAL adhesive exhibited good antibacterial, flame-retardant, and mildew resistance. • The resultant wood-based panel was reusable and biodegradable. [ABSTRACT FROM AUTHOR]

Human health and environmental protection demand wood-based panel industry for innovative soy-based adhesives with high production efficiency, straightforward synthesis processes, non-toxicity, and high bonding performance. A simple and efficient microwave pretreatment process and low addition of bio-derived crosslinking agent was used in this study to prepare a non-toxic and high-bonding performance soybean protein-based adhesive. After 4 min of microwave pretreatment time, the complex quaternary structure of soybean protein molecule unfolds, the soybean protein disperses evenly and stably, and active groups of soybean protein molecules are exposed. After adding 3.85% crosslinking agent, the moisture absorption rate of the soybean protein-based adhesive decreases by 41.77%, the residual rate increases by 3.68%, and the wet shear strength of the resultant plywood increases to 1.12 MPa, which satisfies requirement of interior use plywood. Compared with previously reported soy-based adhesives, this adhesive is dependent on fewer chemical reagents, but has good bonding performance. The 204.41% of relative cell viability indicates the resultant adhesive was non-toxic. The proposed high-efficiency, high-performance, non-toxic biomass adhesive has great prospects for the industrial application. • A non-toxic and high-performance soybean protein-based adhesive was developed. • Microwave treatment (MT) breaks soybean protein molecule and exposes active groups. • After 4 mins MT, the wet shear strength of resultant plywood increased by 160.47%. • MT reduces the dosage of chemical reagent for soybean protein-based adhesive. • Relative cell viability of modified soybean protein-based adhesive reaches 204.41%. [ABSTRACT FROM AUTHOR]

Formaldehyde adhesive is the primary source of indoor formaldehyde pollution, posing a serious threat to human health. Soybean meal (SM), as an abundant biomacromolecule and co-product of soybean oil industry, emerges as a promising alternative to formaldehyde adhesive. However, the SM adhesive exhibits inferior water resistance and unsatisfactory bonding strength. In this study, a novel core–sheath structure with an inexpensive pulp cellulose core and a hyperbranched polymer sheath is synthesized and introduced into SM to develop a robust bio-based adhesive. Specifically, aldehyde-functionalized pulp cellulose is grafted with hyperbranched polyamide, which is terminated via epoxy groups, to synthesize a core–sheath hybrid (APC@HBPA-EP). The core–sheath APC@HBPA-EP serves as both a crosslinker and an enhancer. The results show that the wet shear strength of the modified SM adhesive exhibits a remarkable 520 % increase to 0.93 MPa, and its dry shear strength reaches 2.10 MPa, meeting the established indoor use standards. The Young's modulus of the modified SM adhesive shows a significant 282 % increase to 19.27 GPa. Additionally, the modified SM adhesive exhibited superior impact toughness (7.48 KJ/m2), which increased by 24 times compared with pure SM adhesive. This study provides a versatile strategy for developing robust protein adhesives, hydrogel patch, and composite coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

Petroleum-derived formaldehyde resin adhesives are serious hazards to human health and depend on limited resources. Abundant, cheap and renewable biomass materials are expected to replace them. However, the contradictory mechanisms of high mechanical strength and fracture toughness affect the use of bioadhesives. Herein, a biomimetic soybean meal (SM) adhesive inspired by the structure of insect cuticles and shell pearl layer was proposed. Specifically, chitosan (CS@DA) modified 3,4-dihydroxybenzoic acid (DA, rich in catechol moiety) was anchored on molybdenum disulfide nanosheets (MoS 2) to construct a biomimetic structure with copper hydroxide and SM substrate (SM-MoS 2 /CS@DA-Cu). Schiff base, ionic, and hydrogen bonding strengthened the cohesion of the adhesive. The ordered alternating stacking "brick-mortar" structure stimulated the lamellar sliding and crack deflection of MoS 2 , synergistically reinforcing the toughness. Compared to SM adhesive (0.57 MPa and 0.148 J), the wet shear strength and adhesion work of the SM-MoS 2 /CS@DA-Cu were 1.68 MPa and 0.867 J, with 194.7 % and 485.8 % increases, respectively. The multiple antimicrobial effects of CS@DA, Schiff base, and Cu2+ increased the applicability period of the adhesive to 40 days. The adhesive also displayed favorable water resistance and flame retardancy. Therefore, this peculiar and efficient biomimetic structural design inspired the development of multi-functional composites. [ABSTRACT FROM AUTHOR]

Plant based proteins are green, sustainable, and renewable materials that show the potential to replace traditional formaldehyde resin. High performance plywood adhesives exhibit high water resistance, strength, toughness, and desirable mildew resistance. Adding petrochemical-based crosslinkers is not economically viable or environmentally benign; this chemical crosslinking strategy makes the imparted high strength and toughness less attractive. Herein, a green approach based on natural organic-inorganic hybrid structure enhancement is proposed. The design of soybean meal-dialdehyde chitosan-amine modified halloysite nanotubes (SM-DACS-HNTs@N) adhesive with desirable strength and toughness enhanced by covalent bonding (Schiff base) crosslinking and toughened by surface-modified nanofillers is demonstrated. Consequently, the prepared adhesive showed a wet shear strength of 1.53 MPa and work of debonding of 389.7 mJ, which increased by 146.8 % and 276.5 %, respectively, due to the cross-linking effect of organic DACS and toughening effect of inorganic HNTs@N. The introduction of DACS and Schiff base generation enhanced the antimicrobial property of the adhesive and increased the mold resistance of the adhesive and plywood. In addition, the adhesive has good economic benefits. This research creates new opportunities for developing biomass composites with desirable performance. • A bio-based adhesive was prepared by an organic-inorganic enhancement strategy. • The organic-inorganic hybrid structure endowed the adhesive with high shear strength and water resistance. • The addition of dialdehyde chitosan and nano-filler enhanced the crosslink density and toughness of the adhesive. • The mold resistance and working life of the adhesive have been improved significantly. [ABSTRACT FROM AUTHOR]