Facile preparation of physically crosslinked hydrogel based on the glassy state with high strength

Hydrogels are promising materials, but because of their weak mechanical performance, further applications are limited. To enhance the strength of hydrogels, physical cross-linking was introduced by the use of hydrophobic unit diacetone acrylamide (DAAM) to form cross-linking points. The homopolymer of DAAM exhibited a high glass transition temperature above 80 °C, which was confirmed by DSC. The existence of the glassy and hydrophobic phases in the hydrogel was confirmed by XRD test results. The mechanical properties of the hydrogel were satisfactory, with a maximum tensile strength of 1.96 MPa, rapid recovery ability, satisfactory elasticity, and recyclability. A conductive hydrogel was prepared by introducing sodium ions, and it was used for human motion monitoring and is expected to be a promising material for flexible strain sensors.