Preparation And Properties Of Cellulose-based Rapid Response Multifunctional Hydrogel

Recently,smart hydrogels have been prepared and investigated by the interpenetrating network method based on natural polymer hydrogels,which have received widespread attention and applications in the field of polymer materials.The response rate of the smart hydrogel in practical applications is also very important.Temperature-sensitive conductive hydrogels have both temperature response ability and excellent electrical properties of conductive polymers.Therefore,natural polymer cellulose,temperature-sensitive polymer poly-N-isopropylacrylamide,and conductive polymer polypyrrole,were used to construct a hydrogel network,which had the rapid swelling performance,good temperature-sensitivity performance and conductive properties.The composite material will have a wide range of applications.In this study,cellulose hydrogel was first prepared by chemical crosslinking method.The porous hydrogels were prepared with the urea hydrolysis in the acid condition.Further,based on the porous framework of cellulose gel,cellulose temperature-sensitive hydrogels were prepared by an IPN method.Finally,polypyrrole was polymerized inside the cellulose temperature-sensitive hydrogel by in-situ oxidation polymerization to obtain cellulose temperature-sensitive conductive hydrogel.The research is mainly carried out from the following three aspects:（1）Cellulose was dissolved at-12℃ with the Na OH/Urea system to obtain cellulose solution,and epichlorohydrin was used as cross-linking agent to construct cellulose hydrogel by chemical crosslinking.Acetic acid solution with concentrations of 0,2 wt%,4wt%and 6 wt%were used to treat the hydrogel for certain time to increase the porosity of the hydrogel.With the increase of acid treatment concentration,more porous structures appeared in the hydrogel,and the specific surface area increased greatly.The swelling rate of the hydrogel were also improved significantly.（2）On the research basis of porous hydrogels,poly-N-isopropylacrylamide was synthesized on the cellulose porous hydrogel framework using an IPN method to construct temperature-responsive hydrogel.With the increase of acid treatment concentration,the gel swelling rate and deswelling rate to reach equilibrium were significantly improved.The phase transition temperature of the hydrogel increased with the increase of the amount of cross-linking agent in the temperature-sensitive hydrogel.（3）Polypyrrole nanoparticles were synthesized on the cellulose rapid response temperature-sensitive hydrogel framework by in-situ oxidation polymerization.The thermal decomposition temperature of the composite hydrogel decreased slightly.With the increase of the pyrrole concentration,electrical conductivity of the composite conductive hydrogel had an increasing trend and the conductivity of the hydrogel was up to 9.5×10^-4 S/cm.