Tougher when stressed
Hydrogels are typically weak materials because they contain only a small fraction of polymeric material highly swollen with water. Strength can be increased by adding extra cross-linking or interpenetrating networks with some sacrificial bonds to enhance toughness; however, these properties deteriorate upon stretching and may be slow to recover after relaxation. Liu et al. developed polyethylene glycol hydrogels cross-linked with moderate fractions of polymers that form sliding rings. These allow the chain to orient in parallel when stretched, leading to rapid and reversible strain-induced crystallization and thus much tougher hydrogels.
Publication : Science（6/4）
Title : Tough Hydrogels with Rapid Self-reinforcement
Author : Chang Liu, Naoya Morimoto, Lan Jiang, Sohei Kawahara, Takako Noritomi, Hideaki Yokoyama, Koichi Mayumi*, Kohzo Ito*
DOI : 10.1126/science.aaz6694