ACS Appl. Mater. Interfaces 2026, 18,   7452-7461

Keywords: metal coordination bond,   self-healing, macroscopic damage, shape memory polymer, toughness

Self-healing polymers significantly   extend the service life and enhance the operational reliability of devices.   However, conventional self-healing polymers are often ineffective against   macroscopic deformations and holes. Shape memory-assisted self-healing   (SMASH) provides a feasible solution to this challenge. Efficient shape   recovery relies on stable cross-links. While chemical cross-links provide a   powerful driving force for shape recovery, they inherently hinder   self-healing due to their irreversibility. Conversely, weak physical   cross-links generally result in lower tensile strength and unsatisfactory   shape recovery. Herein, metal coordination bonds are utilized as dynamic   cross-links to construct tough thermal-step-responsive SMASH polyurethanes.   Strong Zn2+-pyridine coordination bonds endow the elastomers with the ability   to repair macroscopic punctures. Without external load intervention,   centimeter-sized punctures (d = 1.4 cm) in such elastomers can autonomously   close within 1 min at 40 degrees C, followed by complete healing at 70   degrees C to repair macroscopic damage. These coordination bonds serve as   dynamic cross-links to significantly enhance mechanical properties (49.71 MPa   for strength and 138.17 MJ/m3 for toughness). The coordination cross-links   play three key roles in the repair process: (1) during the damage process,   they act as network anchors to ensure maximum storage of entropic energy   within the polymer network; (2) during hole closure, they facilitate   efficient release of this stored energy to provide the recovery driving   force; and (3) during the healing stage, their reversible dissociation   releases polymer chains, which accelerates dynamic bond exchange at the   damaged interfaces. This study provides valuable insights into developing tough   self-healing soft materials for macroscopic damage repair.

Jie Zheng, Zhongxin Ping, Fang Xie, Yanju   Liu, Jinsong Leng

Tough Thermal-Step-Responsive Shape Memory-Assisted Self-Healing Elastomers for Macroscopic Puncture Repair.pdf