Self-healing polymers

A polymer network composition comprising a transesterification catalyst and a polymer network dually crosslinked by Diels-Alder reaction products of maleimide groups and furan groups as dissociative covalent bonds and ester groups as associative covalent bonds;

• wherein the dually crosslinked network further comprises hydroxyl groups;
• wherein at least part of the ester groups providing the associative covalent bonds of the dually crosslinked polymer network, and at least part of the hydroxyl groups comprised in the dually crosslinked polymer network, are present as β-hydroxyesters;
• and wherein the amount of dissociative covalent bonds, relative to the sum of dissociative and associative covalent bonds crosslinking the network, is at least 5%.