Synthesis And Performances Of Chitosan-based Biodegradable Intelligent Hydrogels Under Microwave Irradiation

The aim of this work is to prepare the environmental sensitivity of CS/PVP/PVA intelligent hydrogels by microwave radiation with CS as matrix and glutaraldehyde as cross-linking.In this study,the process conditions and influence factor on chitosan-based hydrogels were investigated.In addition,we also discussed the drug release property,sensitive property and biodegradable as well as the swelling and deswelling performance.The structures and proerties of hydrogels were characterized by FTIR,SEM,DSC and TG,and carried of the preliminary discussion on its related mechanism.The main contents of this dissertation are as follows:(1)the preparation of intelligent hydrogels,the environmental sensitivity of CS/PVP/PVA intelligent hydrogels were prepared by microwave radiation.The ratio of hydrogel materials,dosage of crosslinking agent and initiator and the radiation power and radiation time were explored as the influence factors.Results showed that we can obtain the ideal intelligent hydrogel under the condition of the PVP:CS = 2:1,initiator dosage was 5.14 wt.%(relative to the PVP),the dosage of crosslinking agent 1.5 wt.%and the radiation power and radiation time were respectively in 535W and 120s or 370W and 140s.(2)Properties test on coupled hydrogels indicated that the hydrogels has good drug release propertie,environmental sensitivity,degradation and swelling and deswelling under pH=2 solutions at 45℃,and its maximum swelling ratio can achieve 2200%,and the drug release ratio is maximum at this temperature,but under this pH,the drug release ratio is minimal.As can be seen from the temperature sensitivity test,with the increase of temperature,the gel equilibrium swelling ratio showed increasing trend,and had a mutation at about 45℃,then the equilibrium swelling ratio showed decreasing trend.PH sensitivity test showed that the gel has the maximum swelling rate at pH=2.Drug release performance test showed that the hydrogel drug release ratio is maximum at 45 ℃,and with the increase of pH,the drug release ratio decrease.(3)By comparison with preparation method,the performance of hydrogel which was prepared by microwave radiation is stable than the hydrogel was prepared by water bath,temperature/pH impulse response was more regular,because of its stable structure,resulted in the degradability and deswelling of hydrogel is slightly less than the water bath method.(4)FTIR showed that the hydrogel system is a half interpenetrating three-dimensional network structure.DSC results showed that there are two forms of water inside the hydrogels,frozen water and not frozen water,and we can seen obviously than the frozen water content is more than not frozen water.TG results showed that the thermal stability of the hydrogel was prepared by microsave is better than the hydrogel was prepared by water bath.SEM results showed that the hydrogel system is uniform and has dense holes,compared with the hydrogel was prepared by water bath,the hydrogel has more smooth surface.