Self-healing hydrogels

Polymer chemistry

Crystallization

Creep

Polymer science

Engineering

Composite material

Stress relaxation

Materials science

Polyethylene glycol

Reinforcement

Chemical engineering

Polymer

Toughness

Science

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. Science , aaz6694, this issue p. 1078

Tough hydrogels with rapid self-reinforcement