Robust and High Self-Healing Efficiency Polyamide-Urea Based on Multiple Hydrogen and Disulfide Bonds with Suitably Packed Hard-Segment Domains Strategy

The inherent conflict between mechanical robustness and autonomous reparability has become a key challenge in the development of self-healing materials. This study addresses this challenge through precise control of hard-segment stacking structures, pioneering a molecular engineering approach for multihydrogen-bonded polyamide–urea (MHPAU) elastomers. By systematically tuning the spacer units of diisocyanate and dihydrazide segments, we optimized the hydrogen-bonding density distribution within the polymer microphase-separated regions. The developed MHPAU elastic materials can achieve a healing efficiency of over 95% in just 6 h at 90 °C. These materials not only maintain a high tensile strength of 20.2 MPa but also exhibit exceptional fracture toughness of 160.1 MJ/m-3, which is 3.2 times higher than that of natural rubber. When the healing time is extended to 8 h, the healing efficiency can further improve to 98%. These achievements stem from the synergistic action of multiple hydrogen bonding networks with disulfide metathesis. This study provides a general design paradigm for polymer matrices in next-generation energetic composites and impact-resistant coatings.