In-use robust and self-healing, on-demand multi-pathway degradations: Bio-based poly(urethane-urea) elastomers with disulfide bonds

초록

The persistent use of petroleum-derived plastics continues to raise serious environmental concerns due to their durability and limited end-of-life options. Here, we report a bio-based polyurethane urea elastomer that simultaneously achieves high mechanical strength (36 MPa), autonomous self-healing with efficiencies up to 98 %, and on-demand multi-pathway degradability. These combined properties arise from a synergistic molecular architecture incorporating aromatic disulfide units and urea linkages. The aromatic disulfide building block provides a rigid conjugated backbone that enhances thermal and mechanical stability, while its dynamic S-S bonds undergo rapid exchange at mild temperatures, enabling efficient self-healing. Urea linkages further introduce dual hydrogen-bond donors, generating a stronger and more directional supramolecular network than urethane linkages and thereby improving cohesion and toughness. In addition, ester-rich bio-based polyols introduce enzymatically cleavable segments into the polymer backbone. This integrated structure effectively overcomes the conventional trade-off between robustness, dynamic functionality, and degradability. The resulting elastomer exhibits outstanding mechanical performance, more than 90 % UV-induced healing at ambient temperature within 24 h, and reliable responsiveness to multiple degradation triggers. Under reductive conditions at 37 degrees C, the elastomer shows more than 99 % mass loss within 4 d; under UV irradiation, clear photodegradation behavior is observed; and under enzymatic exposure, the material undergoes more than 15 % mechanical property reduction after 21 d. These results highlight a versatile and sustainable design strategy for creating strong, adaptive, and environmentally degradable polyurethane urea materials.

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