Visible light induced synthesis of high toughness, self-healing ionic hydrogel and its application in strain sensing

Abstract The conductive hydrogels with high recovery property applied in electronic sensor fields have recently attracted more and more attention. However, it remains a challenge to simply develop gel-based sensors with excellent toughness, recovery ability and stretch stability. In this work, a tough double crosslinked hydrogel (DC-Gel) was obtained from polyvinyl alcohol/poly (acrylic acid) (PVA/PAA) by facilely visible light triggered polymerization and subsequent salt impregnation. The ionic DC-Gels have been proofed with a high toughness (up to 19 MJ/m3), recovery property, self-healing ability and conductivity. The rubber-like flexible network and homogeneous interconnected phase of the ionic DC-Gels were certificated by scanning electron microscope and thermodynamics analysis. The tensile strengths and stretches at break of the ionic DC-Gels closely depended on the acrylic acid (AA) content. Cyclic tensile test results showed that the ionic DC-Gels with the optimized AA content (PVA:AA = 1:5) afforded a good comprehensive mechanical properties and recoverable energy dissipation; the resilience and stress of the hydrogel at a strain of 150 % maintained over 85 % and 1.8 MPa, respectively. When the ionic DC hydrogel was applied to assemble a strain sensor, the excellent resilience is beneficial for precisely and quickly distinguishing the deformation of hydrogel-based sensor. This research provides a potential approach for the development of ion hydrogels with stretchable, self-healing, high resilience and strain-sensitive properties.