Highly Stretchable, Strain-Sensitive, and Antifreezing Macromolecular Microsphere Composite Starch-Based Hydrogel

Starch-based hydrogel is widely used as an excellent biocompatibility and biodegradability material. However, due to the disadvantages of poor mechanical properties, brittleness, and low stretchability attribute that remains a challenge to prepare multifunctional starch hydrogel integrating high stretchability, strength, and conducting capacity. In this study, macromolecular microspheres with various wettability are successfully incorporated into the hydrogel prepared using the carboxymethyl starch and polyacrylamide cross-linked by Fe 3+ and covalent cross-linker, respectively. The obtained double-network (DN) hydrogel performs good mechanical properties (the fracture stress 483 ± 38 kPa and the elongation at break 1615 ± 25%). Impressively, the obtained DN hydrogels by solvent soaking still maintain excellent mechanical strength and flexibility at −40 °C. Furthermore, it can be assembled to be a resistance-type strain sensor to detect multiscale strain. Therefore, the strategy can shed light on the preparation of multifunctional starch-based hydrogel for broad applications.