Core–Shell Nanohybrid Elastomer Based on Co-Deposition Strategy to Improve Performance of Soy Protein Adhesive

Exploitation of a versatile strategy for fabricating a plant protein adhesive with outstanding adhesion and water resistance is a growing concern in the ecofriendly wood industry. Herein, a core–shell nanohybrid elastomer composed of the cellulose nanocrystal (CNC) core and elastic polyurethane shell is prepared via a co-deposition strategy and then used as an efficient reinforcer to improve the performances of soy protein (SP) adhesive. It is found that the core–shell nanohybrid acts as a multiple cross-linker, giving rise to the construction of a stable protein adhesive system. Moreover, owing to the nanohybrid design combining "strong yet tough" qualities, the hard CNC serves to repair the discontinuous protein adhesion layer for a rigid and integrated system, while the elastic polyurethane contributes to energy dissipation, thus endowing the protein adhesive with excellent overall cohesive strength. Given such synergistic effects, the modified SP-based adhesive exhibits a significant improvement in both adhesion and water resistance, particularly achieving a 311.8% increase in wet adhesion strength compared to that of the pristine SP adhesive. This work may provide an effective guide for the preparation and practical application of high-performance plant-protein-based adhesive.