(A-29) Multifunctional Polyurethane Networks Combining Strength, Toughness, and Fast Autonomous Self-Healing Via the Synergy of Multiple Dynamic Bonds

Introduction:: Native tissues such as blood vessels, muscles, and skin exhibit innate self-healing capability after injury. Self-healing polymers are promising for many applications such as healthcare products, biosensors, and wearable electronics, enabling restoration of their physical properties after damage. However, engineering robust and tough materials with superior self-healing efficiency at room temperature has been a challenge because high mechanical strength comes at the cost of decreased polymer chain mobility required for self-healing.


Materials and Methods:: Multi-functional supramolecular polyurethane (SMPU) based elastomers of high toughness, and fast autonomous self-healing capacity at ambient conditions were developed via the synergy of quadruple H-bonds and dynamic boronic ester bonds. The design involves the use of reversible quadruple H-bonding ureido-pyrimidinone (UPy) motifs and soft olefin as side chains to endow the elastomer with toughness and chain flexibility for supporting self-healing. Further crosslinking of the photoreactive olefin groups via dynamic boronic ester bonds provide strength while maintaining self-healing at ambient conditions.


Results, Conclusions, and Discussions:: DSC, SAXS, and AFM analysis of SMPU revealed a T_g value below room temperature, short-range order structure, and microphase separation, respectively, supporting self-healing at room temperature. The elastomer showed high toughness (42.8 MJ m^-3), strength (11.1 MPa), and spontaneously mechanical recovery at ambient conditions. The work demonstrated development of a novel, multi-functional PU with outstanding mechanical properties and enhanced self-healing at ambient conditions, enabling an exciting range of new applications.


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