Preparation of Flexible Self‐Healing Materials With High Interfacial Compatibility via Silanized Waterborne Polyurethane Grafted Cellulose Nanocrystals

ABSTRACT This study strategically incorporated a preferred chain extender (containing reversible disulfide bonds) into the waterborne polyurethane (WPU) backbone. The WPU matrix was subjected to silanization modification, and cellulose nanocrystals (CNC) were uniformly dispersed as multifunctional reinforcing fillers to form a “multi‐reinforced system” (AHWPU‐C X ). Molecular dynamics simulations were employed to elucidate the molecular‐level interfacial interaction mechanism between silanized/unsilanized WPU and CNC. The binding energy between the silanized WPU and CNC increased by 67.5%, and the superior interfacial compatibility guaranteed the overall performance of the composite. The prepared AHWPU‐C 2 exhibits a 20% increase in the temperature corresponding to the peak mass loss rate, a 127% enhancement in tensile strength, a 313% increase in elastic modulus, and an elastic recovery rate as high as 94%. Its self‐healing efficiency reaches 84.6%, realizing an excellent balance between high mechanical performance and efficient self‐healing ability. In addition, AHWPU‐C 2 can be recycled via hot pressing at 120°C. After the first recycling, the tensile strength and elongation at break of AHWPU‐C 2 were restored to 85.4% and 91%, respectively. This work provides a feasible multi‐enhancement strategy for the development of high‐performance WPU, while offering an effective solution to the interfacial compatibility issue between nanofillers and the polymer matrix.