Endowing rubber with intrinsic self-healing properties using thiourea-based polymer

Area of Science:

• Polymer Science
• Materials Science
• Sustainable Materials

Background:

• Self-healing polymers are crucial for sustainable material development.
• Dynamic polymer networks offer autonomous healing but often require external stimuli or fillers, compromising performance.
• Traditional cross-linkers in elastomers limit material properties and longevity.

Purpose of the Study:

• To develop a mechanically robust, resilient, and independently self-healing polymer network.
• To overcome limitations of existing dynamic networks by avoiding external stimulants and fillers.
• To enhance the properties of natural rubber (NR) and epoxidized natural rubber (ENR) through innovative cross-linking strategies.

Main Methods:

• Dual cross-linking of polymer chains using both covalent and non-covalent interactions.
• Incorporation of a thiourea-based polymer, polyether thiourea ethylene glycol (PTUEG), into a natural rubber and epoxidized natural rubber blend (NR-ENR-PTUEG3).
• Utilizing the thiourea linkage for both hydrogen bonding and dynamic covalent interactions to create an adaptable network.

Main Results:

• The NR-ENR-PTUEG3 composite exhibited significantly improved mechanical properties compared to pristine NR, with a tensile stress of 4.8 ± 0.3 MPa and elongation at break of 833 ± 0.1%.
• Achieved 85% recovery of original strength at ambient temperature, demonstrating effective autonomous self-healing.
• The self-healing efficiency and mechanical integrity were directly correlated with the thiourea-based polymer content.

Conclusions:

• The developed dual-crosslinked polymer network provides a promising pathway for creating strong, resilient, and autonomously self-healing materials.
• The material exhibits excellent mechanical performance and longevity, extending the service life of rubber products.
• This approach enables in situ load-bearing capabilities in repaired materials, maintaining essential mechanical characteristics after healing.