To provide epoxy resin with crack healing capability, an epoxy containing both furan and epoxide groups, N,N-diglycidyl-furfurylamine (DGFA), was synthesized through a two-step approach. When it reacted with N,N′-(4,4′-diphenylmethane) bismaleimide (DPMBMI) and methylhexahydrophthalic anhydride (MHHPA), respectively, a crosslinked polymer with two types of intermonomer linkage was yielded. That is, thermally reversible Diels–Alder (DA) bonds from the reaction between furan and maleimide groups, and thermally stable bonds from the reaction between epoxide and anhydride groups. In this way, cured DGFA possessed not only similar mechanical properties as commercial epoxy, but also thermal remendability that enabled elimination of cracks. The latter function took effect as a result of successive retro-DA and DA reactions, which led to crack healing in a controlled manner through chain reconnection.

Coumarin, a traditional perfume substance, serves as a photosensitive crosslinker to construct a polyurethane network. Upon mechanical damage or ultraviolet illumination at a wavelength of 254 nm, the coumarin dimers on the fractured surface that link the polyurethane backbones with one another are cleft, and can be reconnected via irradiation at 350 nm. By using this feature, cracks on the polymer are mended by ultraviolet exposure or even sunlight without the aid of any catalyst. Owing to the reversibility of the photocyclization of coumarin moieties, multiple cycles of crack mending are allowed, as demonstrated by both qualitative and quantitative characterization. This repeated photo-remendability enables the polyurethane to heal the same site in the material more than once, which is of value for practical applications.

Repeated self-healing, reshaping and recycling of a transparent crosslinked polyurethane are enabled by a sunlight triggered reversible disulfide exchange reaction.

Vulcanized rubber made from an industrial formula can be healed and reclaimed by activating the rearrangement of the inherent sulfur crosslinked networks under the catalysis of CuCl₂.

Crosslinked polyacrylate is self-healed and reprocessed through rearrangement of networks based on catalyst-free dynamic exchange of aromatic Schiff base bonds.