A rubber that is almost entirely water and still won't tear.
Two toughening mechanisms in one network, sliding crosslinks and dense entanglement, producing a hydrogel that stretches enormously and refuses to break, while being almost all water.
The property we did not expect is the elasticity. Stretch it hard and let go and it returns to very nearly where it started, recovering about 99.7% of its original shape. Near-perfect recoverability is unusual in any hydrogel, because water-swollen networks normally dissipate energy by breaking something and stay slightly deformed. At 93% water it should be worse, not better.
Carson J. Bruns, Associate Professor, ATLAS Institute and the Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder.
Carson J. Bruns