Multifunctional starch-based conductive hydrogels for smart sensors and flexible supercapacitors

In order to overcome harsh working environments and meet eco-friendly demands, the development of environmentally tolerant and recyclable hydrogels is necessary. Herein, multifunctional conductive hydrogel was successfully constructed by introducing starch into polyvinyl alcohol (PVA)/glycerin (Gly)/lithium chloride (LiCl) hydrogel. Starch is rich in active sites (-OH groups) that provide a variety of physical interactions for the construction of polymer hydrogels. PSGL hydrogel exhibited high conductivity (40.65 mS cm^-1) and outstanding anti-freezing properties (-40 °C). Meanwhile, PSGL hydrogel retained 82.6 % initial weight after 30 days of exposure and 80 % conductivity retention after recycling. The mechanism of Gly and LiCl in inhibiting the freezing and dehydration of hydrogels was further revealed by density functional theory simulations. Moreover, PSGL hydrogel-based sensors had a satisfactory sensitivity (GF = 1.68 at 0-100 %) and accurately detected human motion. Further, by linking the PSGL hydrogel sensors with Internet of Things technology, human-computer interaction was accomplished. Besides, the PSGL hydrogel-based supercapacitors had a specific capacitance of 120.0 mF cm^-2 (0.2 mA cm^-2) and 98.17 % capacitance retention after 10,000 cycles. PSGL hydrogel-based devices also worked steadily in extreme environments. Therefore, the PSGL hydrogels have great potential for flexible electronics, soft robotics, energy storage etc.