Smart Conductive Hydrogel Based on Carboxymethyl Cellulose/Polyvinyl Alcohol/Glycerol Crosslinked by Borax Acid

Abstract

Conductive hydrogel is an important material that has been applied as bioactuators and health recording electrodes. The using of conductive hydrogel still has limitations. The loss of water in hydrogel at operating temperature decreases hydrogel properties. To overcome this obstacle, this study aims to develop smart conductive hydrogel with self-healing, anti-freezing, anti-drying.  The conductive hydrogel can be prepared based on carboxymethyl cellulose (CMC)/ polyvinyl alcohol (PVA)/glycerol (GA) crosslinked by various borax acid content at 0-25 wt%. Based on the results, the conductive hydrogel containing 5-25 wt% showed relative resistance at 15-20 %. The relative resistance decreased with increasing borax acid in samples. The dissolved borax acid in hydrogel created borate ions which acted as electrolyte in hydrogel. The self-healing ability were observed at 30-360 minutes. The time for self-healing decreased with increasing borax acid content. The reversible linkage between borate ion and hydroxyl groups of CMC/PVA/GA resulting in self-healable phenomenon. The tests of anti-drying were performed at 30^oC, for 7 days. The weight loss of PVA/CMC was 80% whereas PVA/CMC/GA was 5%. The GA in hydrogel acted as cryoprotectant which remarkably improve hydrogel stability over 1 week. The obtained conductive hydrogel has potential to apply as strain-sensitive sensors.