T-shaped trifunctional crosslinker-toughening hydrogels

Currently, development of a single network hydrogel with a high fracture toughness in swelling equilibrium remains challenging. In this work, a novel T-shaped trifunctional crosslinker (T-NAGAX) with dual vinyl on the backbone and dual amide group on the side chain is synthesized by Michael addition and acylation. The T-NAGAX is used to prepare chemically crosslinked hydrogel by one-pot photo-initiated polymerization. The resulting single network hydrogels of representative polyacrylamide (PAAm), poly(N-acryloyl 2-glycine) (PACG), and poly(N-isopropyl acrylamide) (PNIPAM) crosslinked with T-NAGAX with additional hydrogen-bonds exhibit much better fracture toughness than that of the corresponding hydrogels crosslinked by N,N′ -methylene bisacrylamide, a conventional crosslinker; higher mechanical strengths are observed in the T-NAGAX crosslinked hydrogels. These hydrogels are promising to be exploited as load-bearing soft tissue substitutes. This T-NAGAX crosslinker can be expanded to toughen various types of hydrogels.