Engineering materials and devices can be damaged during their service life as a result of mechanical fatigue, punctures, electrical breakdown, and electrochemical corrosion. This damage can lead to unexpected failure during operation, which requires regular inspection, repair, and replacement of the products, resulting in additional energy consumption and cost. During operation in challenging, extreme, or harsh environments, such as those encountered in high or low temperature, nuclear, offshore, space, and deep mining environments, the robustness and stability of materials and devices are extremely important. Over recent decades, significant effort has been invested into improving the robustness and stability of materials through either structural design, the introduction of new chemistry, or improved manufacturing processes. Inspired by natural systems, the creation of self‐healing materials has the potential to overcome these challenges and provide a route to achieve dynamic repair during service. Current research on self‐healing polymers remains in its infancy, and self‐healing behavior under harsh and extreme conditions is a particularly untapped area of research. Here, the self‐healing mechanisms and performance of materials under a variety of harsh environments are discussed. An overview of polymer‐based devices developed for a range of challenging environments is provided, along with areas for future research.

When introducing self-healing properties to elastomers, it is often difficult to balance their ability to recover properties after damage with a good mechanical strength prior to damage. We demonstrate that by replacing the activator system used in conventional accelerated vulcanization (CV) chemistry, from the traditional zinc oxide (ZnO) and stearic acid to a complex formed between ω-propenyl functional oligomers of poly(zinc methacrylate) (pZnMA/ZnO), the self-healing properties of vulcanized natural rubbers are enhanced while maintaining good tensile strengths. The pZnMA oligomers, as synthesized by catalytic chain transfer polymerization (CCTP), act as an activator for the sulfur curing system, while also forming an ionic network in the rubber. The addition of 20 phr of pZnMA/ZnO to a CV system resulted in a cured natural rubber with a tensile strength of 7.47 ± 0.64 MPa, which recovered 86.7% after self-healing at 80 °C for 2 h. Further addition of 40 phr of carbon black N234 unexpectedly enhanced the self-healing efficiency of these vulcanized rubbers to 92.2% under the same conditions and also improved the self-healing at room temperature. Finally, dynamic mechanical thermal analysis indicated that the natural rubber formulations containing pZnMA/ZnO showed improved wet traction but with higher rolling resistance to a standard formulation. These results point to an interesting direction for further research into the performance of self-healing composites in vehicle tire applications.

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