Ultrathin tough double network hydrogels showing adjustable muscle-like isometric force generation triggered by solvent.

Ultrathin double-network hydrogels, which have super-high toughness under micro-scale thickness (elastic elongation epsilon(b) > 1000%, tensile strength sigma(b) > 2 MPa and tearing energy G approximately 600 J m(-2)), and solvent-triggered fast and high isometric stress generation, were synthesized by coupling the salt-controlled swelling process and polymer chain pre-reinforced technique.