Super tough, stretchable and transparent ionic conductive hydrogel for flexible sensor with excellent temperature tolerance

Abstract

The construction of high performance ionic conductive hydrogel together with strength, toughness, transparency, environment tolerance, stable conductivity and response is still an urgent demand in flexible sensing field. Here, a simple and feasible strategy was proposed to produce ionic conductive hydrogels by integrating polyvinyl alcohol (PVA)/silk sericin (SS) with sodium citrate (Na3Cit) in glycerol (Gl)/water solution. The synergistic action of physical cross-linked polymer networks and supra-molecular interactions enabled the resultant PVA/SS/Na3Cit/Gl hydrogels with super strong (7.56 MPa), tough (39.37 MJ/M3), stretchable (787.96%) and transparent (90%). Especially, the PVA/SS/Na3Cit/Gl hydrogels displayed excellent extreme temperature tolerance, retaining highly stretchability (> 500% strain), strong (7–12 MPa) and tough (25–52 MJ/M3) at −25 to 60 °C or 7 d storage at 30 °C. Profiting from these advantageous performances, PVA/SS/Na3Cit/Gl hydrogels could be assembled as transparent flexible sensors to quickly and precisely response human activities with a wide strain range (up to 200% strain), excellent stability and repeatability even at −25 °C or 7 d storage. In addition, PVA/SS/Na3Cit/Gl hydrogels showed cytocompatibility with good cell proliferation of Cos 7 fibroblasts within 72 h incubation. Thus, the presented PVA/SS/Na3Cit/Gl hydrogels suggested a promising prospect as reliable wearable electronics adapting to mechanical and environmental durability.