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

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Self-healing polymers enhance device longevity and reliability.
• Conventional polymers struggle with macroscopic damage and deformation.
• Shape memory-assisted self-healing (SMASH) offers a solution but faces challenges with cross-link stability.

Purpose of the Study:

• To develop tough, thermal-step-responsive SMASH polyurethanes using dynamic metal coordination bonds.
• To enable autonomous repair of macroscopic damage in soft materials.
• To investigate the role of coordination bonds in enhancing mechanical properties and self-healing capabilities.

Main Methods:

• Utilized Zn2+-pyridine coordination bonds as dynamic cross-links in polyurethane elastomers.
• Investigated the thermal-step-responsive behavior for shape recovery and healing.
• Characterized mechanical properties, including strength and toughness.
• Evaluated the autonomous repair of centimeter-sized punctures at different temperatures.

Main Results:

• Developed SMASH polyurethanes with enhanced mechanical properties (49.71 MPa strength, 138.17 MJ/m³ toughness).
• Achieved autonomous closure of 1.4 cm punctures within 1 minute at 40 °C.
• Demonstrated complete healing of macroscopic damage at 70 °C.
• Identified three key roles of coordination cross-links in energy storage, release, and chain mobility during repair.

Conclusions:

• Metal coordination bonds are effective dynamic cross-links for creating tough, self-healing soft materials.
• The developed SMASH polyurethanes can autonomously repair macroscopic damage, significantly extending material service life.
• This approach provides valuable insights for designing advanced self-healing materials for demanding applications.