Figure 1. Overview of different strategies to make tough hydrogels and their biomedical applications.

Schematic representation of strategies used to formulate tough hydrogels, namely, Tetra-PEG, click chemistry, radiation crosslinked, slide ring, fiber/filler enforced networks, interpenetrating network hydrogels, double network, nanocomposite, and macromolecular microsphere composite hydrogels. Such specialty tough hydrogels have shown exciting promise as tough coatings and adhesives, and for use in soft actuators, drug delivery, and tissue engineering applications.