text: Supramolecular polymers may be relevant to self-healing materials.  A supramolecular rubber based on vitrimers can self-heal simply by pressing the two broken edges of the material together. High mechanical strength of a material and self-healing ability are generally mutually exclusive. Thus, a glassy material that can self-heal at room temperature remained a challenge until recently. A supramolecularly polymer based on ether-thiourea is mechanically robust (e= 1.4 GPa) but can self-heal at room temperature by a compression at the fractured surfaces.  The invention of self-healable polymer glass updated the preconception that only soft rubbery materials can heal. 
  Another strategy uses a bivalent poly(isobutylene)s (PIBs) functionalized with barbituric acid at head and tail. Multiple hydrogen bonding existed between the carbonyl group and amide group of barbituric acid enable it to form a supramolecular network. In this case, the snipped small PIBs-based disks can recover itself from mechanical damage after several-hour contact at room temperature.
  Interactions between catechol and ferric ions exhibit pH-controlled self-healing supramolecular polymers. The formation of mono-, bis- and triscatehchol-Fe complexes can be manipulated by pH, of which the bis- and triscatehchol-Fe complexes show elastic moduli as well as self-healing capacity. For example, the triscatehchol-Fe can restore its cohesiveness and shape after being torn. Chain-folding polyimide and pyrenyl-end-capped chains give rise to supramolecular networks.