Ionic organohydrogel with long-term environmental stability and multifunctionality based on PAM and sodium alginate

Abstract

Hydrogels possess several advantageous characteristics, including transparency, biocompatibility, and ionic conductivity, making them promising for applications in flexible electronics, drug delivery, ionic skin, and electrolytes. Nevertheless, creating a robust conductive and antifreezing hydrogel with enduring environmental stability remains a significant challenge. This study, based on the salt-out effect of alkali metal ion salts and binary solvent systems, employs a straightforward one-pot solvent exchange method to introduce dynamic and reversible non-covalent bonds (hydrophobic association and hydrogen bonds) into a polyacrylamide-sodium alginate (PAM-SA) dual-network hydrogel with excellent flexibility and biocompatibility. By adjusting the types of ions and cryoprotective agents (CPA), a series of ion-conductive organic hydrogels with anti-freezing properties were successfully prepared. The resulting PAM/SA-Gly-KCl1M hydrogel exhibits commendable mechanical properties (with a tensile strain of up to 1465 %, a tensile strength of 166 kPa, and toughness of 1354 kJ m3), high ionic conductivity (0.59 S/m), outstanding frost resistance (–100 °C), and sustained long-term stability (maintaining 70 % of its weight for over one month in an open environment). Therefore, sensors based on organic hydrogels exhibit exceptional characteristics, including high strength, superior transparency, and dependable operation in low-temperature conditions. Its remarkable sensing sensitivity and stability and antifreeze properties facilitate operation across an extensive temperature range and contribute to an extended operational lifespan. Overall, this sensor proves conducive to developing enduring flexible electronic products in challenging environments, thereby unveiling novel prospects for the realms of smart wearable technology and health monitoring.