Multifunctional Polyurethane Networks Combining Strength, Toughness, and Fast Autonomous Self-Healing via the Synergy of Multiple Dynamic Bonds

Polymeric materials exhibiting concomitant toughness,strength,and autonomous self-healing at room temperature are attractive inmany applications. However, the mechanical strength often compromisesthe self-healing capability, making development of such materialschallenging. Here, we developed multifunctional supramolecular polyurethane(PU) based elastomers of high toughness and fast autonomous self-healingcapacity at ambient conditions via the synergy of quadruple H-bondsand dynamic boronic ester bonds. The design involves the use of reversiblequadruple H-bonding ureido-pyrimidinone (UPy) motifs and soft olefinside chains to endow the elastomer with toughness and chain flexibilityto support self-healing. Further cross-linking of the photoreactiveolefin groups via dynamic boronic ester bonds by thiol-ene chemistryprovided strength while maintaining self-healing at ambient conditions.The resulting elastomers (PU-Ene( x )) showedhigh toughness (42.8 MJ m(-3)), strength (11.1 MPa),notch insensitivity, and high fracture energy (23.6 kJ cm(-2)). Notably, PU-Ene( x ) demonstrated fastself-healing at room temperature, recovering almost 90% of their originaltoughness within 6 h postinjury. Finally, they also exhibited remarkableadhesive strength (1.0 MPa), high optical transparency, and strongblue fluorescence upon UV irradiation. The work demonstrates the developmentof a novel, multifunctional PU with outstanding mechanical propertiesand enhanced self-healing at ambient conditions, enabling an excitingrange of new applications.

Automated summary

Multifunctional supramolecular polyurethane elastomers with high toughness and fast autonomous self-healing capacity at room temperature were developed. The elastomers exhibited high strength, notch insensitivity, and high fracture energy, and recovered almost 90% of their original toughness within 6 hours post-injury.