Highly Porous, Biocompatible Tough Hydrogels, Processable via Gel Fiber Spinning and 3D Gel Printing
Conventional tough hydrogels offer enhanced mechanical properties and high toughness. Their application scope however is limited by their lack of processability. Here, a new porous tough hydrogel system is introduced which is processable via gel fiber spinning and 3D printing. The tough hydrogels are produced by rehydrating processable organogels developed by induced phase separation between two linear polymer chains capable of intermolecular hydrogen bonding. Through a slow sol–gel phase separation, highly porous gel networks made of hydrogen bonded polymer chains is formed. These organogels can be easily transformed to 3D printed multimaterial constructs or gel fibers, and after rehydration produce highly robust hydrogel structures. Although such hydrogels are highly porous and contain large amount of water, their strength can reach as high as 2000 kPa, with high elongation at break (≈900%), and tunable moduli ranging from 250 to 2000 kPa. The hydrogels have fracture energies larger than cartilage and demonstrate excellent load recovery because of their renewable hydrogen bond crosslinks. Furthermore, the hydrogels exhibit excellent hemocompatibility and in vitro biocompatibility. Such hydrogels can further expand the application of tough hydrogels and may serve as a model to explore the toughening mechanism of hydrogen bonded hybrid, tough hydrogel systems.