Construction of high strength PVA/cellulose conductive hydrogels based on sodium citrate/aluminium chloride dual ions regulation.

Hydrogels used for flexible sensing usually require a good balance between mechanical strength and conductivity. In this study, polyvinyl alcohol/carboxymethyl cellulose/cellulose nanofibers (PVA/CMC/CNF) hydrogels with multi-hierarchical structures were firstly prepared by adjusting the CNF content. Then, PVA/CMC/CNF-xM with excellent mechanical properties and conductivity were prepared by cyclic freezing-thawing and sodium citrate/aluminium chloride (NaCit/AlCl) dual ions salt equilibrium methods. Results showed that at an ion concentration of 3 mol/L, PVA/CMC/CNF-3 M hydrogel exhibited a tensile strength, elongation at break and conductivity of 3.41 MPa, 1271 % and 0.35 S/m, respectively. The structural evolution of PVA/CMC/CNF-xM conductive hydrogels were studied, and the results indicated that Cit formed numerous intermolecular hydrogen bonds, while Al could strongly coordinate with carboxyl and hydroxyl groups between the polysaccharide chains. Meanwhile, PVA/CMC/CNF-3 M possessed a low strain detection limit of 1 %, making it not only can be used for human motion monitoring, but also information encoding and transmission. This work may provide a facile approach for preparing high-strength and conductive hydrogels, which can be applied in flexible wearable electronic devices and information transmission.