Underwater self-healing of microphase-separated PLLA–b–PTMC biocompatible elastomers

Waterproof and self-healing materials are crucial for preventing leakage in implantable devices subjected to cyclic mechanical stress. Herein, we investigate how block composition governs the underwater self-healing behavior of biodegradable elastomers composed of poly(L-lactic acid) (PLLA) and poly(trimethylene carbonate) (PTMC). By tuning the PLLA/PTMC ratio, we modulated crystallinity and segmental mobility, with soft PTMC domains disrupting PLLA ordering and enhancing chain dynamics. Molecular dynamics simulations and thermal analysis revealed increased diffusivity and looser chain packing in PTMC-rich regions. In parallel, electrostatic potential mapping and surface energy analysis indicated reduced interfacial polarity, favoring hydrophobic polymer–polymer interactions under wet conditions. This work demonstrates a design strategy that integrates segmental dynamics and interfacial modulation to achieve water-tolerant self-healing in biodegradable polyesters, offering promise for biomedical sealing and tissue repair.