Zwitterionic Fusion in Hydrogels and Spontaneous and Time-Inde Pendent Self-Healing Under Physiological Conditions

Self-healing materials can eliminate damage or fatigue during normal utilization, thus holding promise for enhanced lifetimes and enduring strength. They have been demonstrated by exploiting polymer-clay interactions, phase segregation, redox reactions, photo-reactive groups, and microvascular networks. However, up to now few materials have been reported to be effective in spontaneously repairing themselves under physiological conditions upon damage. For these few existing spontaneously self-healing materials, healing can only be achieved immediately after rupture occurs (i.e. in less than one minute) or at low pH values. Here, we report the first spontaneously healing material, driven by a completely new mechanism, zwitterionic fusion. It can repair at any lengths of separation time after damage (i.e., time-independent behavior) without any healing agents added or external energy input. As a result, two or more pieces of hydrogels can be re-connected easily after separation. In addition, this hydrogel demonstrates exceptional non-fouling behavior and efficient functionalization, which make them also suitable for biomedical-related applications.