Self-healing polymers and composites for extreme environments†
Self-healing polymers and composites utilizing the Diels–Alder reaction have received considerable attention due to the intrinsic healing capability of this crosslink. However past research focused on chemistries that cleave at low temperatures, which places limitations on the polymer's use temperature. Here, it is demonstrated that the crosslinking Diels–Alder (DA) reaction between anthracene and maleimide moieties can be used to achieve healing efficiencies greater than 94% for polymers and 69% for carbon fiber reinforced polymer composites while remaining stable beyond 240 °C. It is shown that the self-healing behavior can be obtained purely through the reformation of mechanically cleaved DA adducts since the cleaving temperature is beyond the decomposition temperature. The self-healing polymer reported here is obtained from liquid monomers allowing the polymerization of bulk polymer samples and its infusion into continuous fiber reinforced composites. It is shown that the polymer can yield thermally stable composites with mechanical properties comparable to those of other engineering polymers and structural composites.