Activation and deactivation of self-healing in supramolecular rubbers

A remarkable self-healing property has been achieved recently with rubbers formed by a supramolecular network of oligomers. Here we explore this property through a tack-like experiment where two parts of supramolecular rubber are simply brought into contact and then taken apart. These experiments reveal that the self-adhesive strength of rubber surfaces is significantly enhanced by fracture or other damaging processes. The mechanical energy required to separate two fracture surfaces that were brought back into contact is about one order of magnitude larger than that for surfaces close to thermodynamic equilibrium. Moreover, we find that fracture faces stored apart at room temperature still self-heal after 12 h but that this self-healing can be fully deactivated within a couple of hours by annealing around 90 degrees C. More generally, these results provide useful quantitative data to investigate the intensity and kinetics of self-healing in these soft rubbers.