UCLA

A kind of ultra tough and strong PVA hydrogel is prepared via acidifying PVA solution, freeze-thawing, and salting-out. By adding acid to the PVA precursor, the PVA chains are protonated, which inhibits the formation of PVA crystal regions during the freeze-thawing, leading to better chain mobility. Therefore, in the salting-out step, the mobile PVA chains can rearrange themselves to a more favorable position, resulting in better mechanical properties. The formed isotropic hydrogel exhibits superior tensile strength (26.7 MPa), stretchability (1650 %), toughness (224 MJ m-3), and fatigue resistance (3.4 kJ m-2). Interestingly, the hydrogel still shows high mechanical properties after removing the salt by soaking it in water owing to its densely entangled conformation.