Preparation And Application Of Chitosan-based Tough And Adhesive Hydrogel

Hydrogels have attracted much more scientific attention because of their high water content and similar to natural tissues.However,at present,most hydrogels have low adhesiveness,poor mechanical properties and too simple properties to meet the application standards.Therefore,it is of great significance to prepare a kind of adhesive and tough hydrogel with multiple functions.In this paper,chitosan was dissolved and cross-linked in one step with ferric chloride solution as solvent,and a chitosan-based adhesive and tough hydrogel mediated by ferric chloride solution was successfully prepared by introducing it into the polyacrylamide chemical cross-linked network.Based on the abundant functional groups in chitosan molecules,the hydrogels could produce intermolecular forces with various organic/inorganic solid materials and biological tissues,thus showing excellent adhesion.Surprisingly,this binding ability also displayed a certain repeatability,which greatly overcame the disadvantage of traditional chemical anchorage that cannot be reused,and improved the service efficiency of hydrogels.In addition,the introduction of chitosan network enabled the hydrogels to exhibit high mechanical properties,with fracture stress up to 135 kPa and fracture strain greater than 2300%.Meanwhile,as the solvent of hydrogel,ferric chloride solution also endowed hydrogel with a certain conductivity and exhibited good strain sensitivity.In order to improve the functionality of hydrogels while maintaining excellent adhesion and toughness.Here,using phosphoric acid,an acidic electrolyte that combines high conductivity,high temperature resistance and supercooling properties,and introduced it into a chemically crosslinked polyacrylamide hydrogel system with phosphoric acid and water as a mixed solvent,which successfully imparted hydrogel with excellent conductivity,longterm stability,and freeze/heat resistance.At the same time,based on the presence of phosphoric acid in the system,sufficient acidic conditions were provided for the dissolution of chitosan molecules,so that it was successfully dissolved and introduced into the hydrogel system,which significantly improved the mechanical and adhesive properties of the hydrogel.Surprisingly,its adhesiveness and toughness remained almost constant over a wide temperature range stability(-60 ? ~ 100 ?).Additionally,the hydrogel also exhibited ultrahigh transparency.Based on the above results,we successfully applied the adhesive and tough hydrogel with high conductivity,transparency and wide temperature range to the supercapacitor as an electrolyte.The device showed good flexibility and wide temperature range stability.We firmly believe that this strategy of thickening and toughening through simple solvent mediated chitosan molecules would greatly broaden the application range of hydrogels and provide new insights for the development of a new generation of multifunctional soft materials.