Bio-based, self-adhesive, and self-healing ionogel with excellent mechanical properties for flexible strain sensor

Abstract

Bio-based ionogels with versatile properties are highly desired for practical applications. Herein, we designed a novel self-healing, anti-freezing, and self-adhesive ionogel with excellent sensor capability. The ionogel was obtained by cross-linking amino groups (chitosan) and aldehyde groups (dextran oxide) to form Schiff-base bonds in the ionic liquids (EMIMOAc) with TA. Ionogels inherited the superior electrical conductivity of ionic liquids (IG₂, 1.1 mS cm⁻¹). Due to the dynamic reaction of Schiff-base bonds, the obtained IG₂ possessed self-healing properties (self-healing efficiency = 89%). The presence of TA also provided the ionogel with excellent self-adhesive properties (IG₂/TA, adhesive strength to hogskin = 8.05 kPa). Owing to the low freezing point and low vapor pressure of ionic liquids, ionogels were endowed with anti-freeze properties and resistance to solvent volatility. Moreover, the ionogel can act as a strain sensor, and exhibited excellent sensitivity and sensing performance. Our work provided a green and effective method in preparation of the high performance ionogel sensor, which could accommodate future practical industrial applications.