POLYURETHANE ELASTOMER WITH CONCURRENTLY ENHANCED MECHANICAL STRENGTH AND SELF-HEALING EFFICIENCY ENABLED BY INTEGRATION OF DYNAMIC BOROXINE AND METAL-LIGAND BONDS

Abstract

Conventional self-healing polyurethanes (PUs) face an inherent trade-off between mechanical strength and self-healing efficiency. We report a dual-dynamic crosslinked PU elastomer (PU-Eu x ) that achieves concurrent enhancement of mechanical properties and self-healing capability by integrating boroxine covalent bonds with physical crosslinks (Eu 3+ –pyridine coordination bonds and hydrogen bonds). With a constant crosslinking density of dynamic boroxine bonds and hydrogen bonds, the mechanical performance can be readily tuned by varying the Eu 3+ content. Notably, the incorporation of 1.0 mmol Eu 3+ increases the Young’s modulus and toughness from 6.59 MPa and 22.22 MJ/m 3 to 24.39 MPa and 43.45 MJ/m 3 . In addition, the material enables rapid healing of surface scratches within 20 min at 60 °C, and under identical healing conditions, PU-Eu 0.5 achieves a self-healing efficiency of 97%. We offer an effective strategy for high-performance self-healing PUs that combine superior mechanical strength with efficient healing, making them promising for wearable electronics, protective coatings, and adhesives.