Fracture and Self-Healing in a Well-Defined Self-Assembled Polymer Network

We studied shear-induced fracture and self-healing of well-defined transient polymer networks formed by telechelic polypeptides, with nodes formed by collagen-like triple helices. When these gels are sheared at a rate that is higher than the inverse relaxation time of the nodes, fracture occurs at a critical stress which increases logarithmically with increasing shear rate. When a constant stress is applied, fracture occurs after a delay time that decreases exponentially with increasing stress. These observations indicate that fracture in these systems is due to stress-activated rupture of triple-helical junctions. After rupture, the physical gels heal completely.