Figure 15.

Self-healing poly(acrylic acid) (PAAc) hydrogels for potential biorobotic applications. (A) (a) Schematic illustration of the structure of the self-healing hydrogel. (b–e) Self-healing of a cylindrical hydrogel (Entry 3) at room temperature: (b) the original hydrogel, (c) the hydrogel after being cut, (d) the hydrogel after the two parts were brought into contact with each other, (e) the hydrogel after healing for 6 h. (f) Stretching the self-healed hydrogel up to 200%. (B) The use of the self-healing nature of the hydrogel to produce complex architectures. (a) The original hydrogel. (b) The hydrogel after being cut. (c–e) The hydrogel segments arranged in the form of letters: U, M, and D, after (c) 1, (d) 3, and (e) 6 h of self-healing. Reproduced with permission from [337]. Copyright 2013, The Royal Society of Chemistry.