High strength, recyclable, anti-swelling and shape-memory hydrogels based on crystal microphase crosslinking and their application as flexible sensor

To develop high strength, anti-swelling, and sustainable hydrogels, acrylonitrile copolymer hydrogels are prepared based on the structural characteristics of microphase separation and physical crosslinking of thermoplastic elastomers. The hydrogel can be recycled and reprocessed into any desired shape and can withstand the maximum tensile stress of about 23 MPa, the maximum fracture energy is as high as 7592 J/m2. The hydrogels exhibit strain hardening behavior at low strain. In addition, the high strength can be maintained stably for more than 60 days in an aqueous environment and the hydrogel has pH-induced shape memory property. The hydrogel can be further strengthened by the introduction of zinc ions, and its toughness and elongation at break are greatly improved, which is mainly based on the dynamic balance between free zinc ions and conjunct zinc ions in the gel. In addition, the introduction of zinc ions also greatly improves the electrical conductivity of the gel. The strain sensor prepared by this gel has high sensitivity, good linear response, and stability, and is expected to be a promising candidate material for flexible electronic products and strain sensors.