Research Progress of Cellulose Self-Healing Hydrogels

Hydrogels are 3D network structure material formed by physical or chemical cross-linking of hydrophilic polymers. It usually has the characteristics of hydrophilicity, viscoelasticity, biocompatibility, etc., and is widely used in bioengineering, flexible electronics and other fields. Traditional hydrogels generally use fossil-based polymers as raw materials, and there are potential threats to the human body and the environment during the use of hydrogels and the recycling of waste hydrogels. At the same time, the traditional hydrogel will be damaged due to the action of mechanical external force after a long time of use, and its structural integrity and performance will be affected. Hydrogels with self-healing ability can recover to almost the same mechanical properties as the initial state after breakage using supramolecular interactions or reversible covalent interactions, which is of great significance for prolonging the service life of hydrogels. Cellulose is a kind of natural organic polymer, with non-toxic, harmless, good biocompatibility and other advantages, mainly from natural materials such as trees in nature, in line with the concept of green environmental protection, has broad application prospects. The abundant oxygen-containing groups in cellulose chain can form hydrogen bond network with water, which is conducive to the preparation of hydrogels with self-healing ability. And by chemically modifying cellulose to obtain cellulose derivatives, such as carboxymethyl cellulose, hydroxyethyl cellulose, etc., its application in the field of hydrogels can be expanded. This paper comprehensively introduces a class of self-healing hydrogels using cellulose and cellulose derivatives as raw materials, analyzes the shortcomings of traditional self-healing hydrogels, and proposes related modification strategies. Cellulose is difficult to dissolve in water due to its own crystal structure and internal supramolecular interactions, so cellulose hydrogels are generally prepared by using a dispersion system or a dissolving system. By regulating the three-dimensional structure of the hydrogel, reversible covalent interactions (acylhydrazone bond, disulfide bond exchange, etc.) and non-covalent interactions (hydrogen bonding, hydrophobic interaction, host-guest interaction, etc.) are used to endow the hydrogel with self-healing ability. Due to the existence of such reversible cross-linking, the general mechanical properties of traditional cellulose self-healing hydrogels are poor. At the same time, the functional development of cellulose self-healing hydrogels is relatively simple at present, which limits its application in various fields. Therefore, by introducing the construction of intelligent network structure, biomimetic natural biological wound healing mechanism and functional modification methods, this paper proposed a new multi-functional intelligent cellulose self-healing hydrogel construction method. Finally, combined with the relevant research results of self-healing hydrogels, the problems that still need to be solved at the present stage of cellulose self-healing hydrogels are put forward, and the application prospect of cellulose self-healing hydrogels in the fields of bioengineering, electronic materials and intelligent materials is forecasted. © 2024 Chinese Society of Forestry. All rights reserved.