Metal ion mediated conductive hydrogels with low hysteresis and high resilience

Abstract

Conductive hydrogels with poor mechanical properties seriously limit the service life of sensors and flexible electronics. Outstanding mechanical properties and electrical conductivity are the bottleneck of the application of conductive hydrogels. To combined excellent elasticity and electronic conductivity, herein, a new method was employed to achieve elastic dissipation with low hysteresis via introduce metal ions crosslinking, thereby enhancing mechanical dissipation of polymer network. Specifically, acrylamide (AAm) is a monomer in the covalent network via free radical polymerization. Sodium alginate (SA) form metal coordination bonds with Fe³⁺, Zn²⁺ and Ca²⁺. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) is selected to be a conductive polymer. The resultant AAm/SA/PEDOT: PSS (ASP) hydrogels exhibit low hysteresis, high resilience and excellent electronic conductivity. Metal coordination bonds not only provide high elasticity as elastic dissipation energy, but also enhance electrical conductivity. The ASP hydrogels display combined mechanical performances with elastic modulus (550 MPa), fracture strength (0.81 MPa), fracture strain (473 %) and work of rupture (3.13 MJ/m³), and outstanding electronic conductivity (0.32 S/cm) which has great potential for extending the service life of hydrogels.