Template method for dual network self-healing hydrogel with conductive property

Abstract

We herein present dual-network self-healing hydrogels via ionic cross-linking and hydrogel bonds based on chitosan molecular chain as a template. Chitosan and poly(acrylic acid) were reacted to form a dual-network structure via Fe3+ ion coordination and hydrogen bonds. The healing property mainly depends on the coordination between Fe3+ ions and COOH or NH2 groups of the polymer chains, as well as on the hydrogen bonds occurring among OH, NH2 and COOH groups. Compared with the covalent cross-linking points, the ionic linkages and hydrogen bonds in the hydrogels were stochastic and dynamic. Hence, if the hydrogel becomes cracked or possesses a notch, the cross-linking points will be destroyed, while the new ones will be re-formed based on the dual-network of the hydrogel. The self-healing efficiency of the as-prepared hydrogel could reach 98.5% when the concentration range of 0.01–0.5M Fe3+ aqueous solution was used. In addition, both the compression resistance and electrical conductivity of the hydrogel were enhanced with FeCl3 content increasing. Therefore, the as-prepared hydrogel exhibited excellent stretchability, compression resistance, self-healing performance without any external stimulus, and electrical conductivity.