Preparation And Characterization Of Polyurethane-Chitosan Sponges

The research of polyurethane-chitosan(PU-CS)composites is a hot spot in the field of biomedicine.In order to solve the problems in the research of polyurethane-chitosan sponge,such as the selection of molecular weight of CS,the improvement of the antimicrobial activity of PU-CS sponge and the preparation of PU-CS block sponge,three PU-CS composite sponges,namely PU-CS sponge with different molecular weight CS as chain extender,PU-HTCS sponge with HTCS as chain extender and PEG-CS30K-PU insertion,were prepared by two-step method.The reaction mechanism and crystalline form of the composite sponge were analyzed.The chemical structure,apparent morphology,swelling property,liquid absorption and retention rate,mechanical properties,protein adsorption performance and in vitro degradation performance of the composite sponge were tested.The PU-HTCS sponge was also tested for bacteriostasis.The main results were as follows:(1)The molecular weight of CS has an important influence on the properties of PU-CS sponge.The reactivity of CS groups with different molecular weight is different;the grafting degree of CS3 K is the highest;the introduction of CS30 K and CS300 K will cause the separation of hard and soft segments of composite sponge,resulting in uneven pore size;with the increase of CS molecular weight,the hydrophobicity and BSA adsorption capacity of PU-CS composite sponge increase,and the equilibrium swelling degree decreases;the degradation of PU-CS sponge in the early degradation stage.The degradation rate was slow,and the degradation rate was accelerated with the increase of CS molecular weight in the later stage.(2)PU-HTCS sponge prepared with HTCS as chain extender has good antimicrobial activity.The molecular weight of CS has an important influence on the properties of PU-HTCS sponge including antimicrobial activity.With the increase of molecular weight of CS,the hydrophilicity,liquid absorption rate and equilibrium swelling degree of PU-HTCS sponge decreased,but overall higher than that of PU-CS sponge prepared in Chapter 1.In vitro degradation performance and protein adsorption performance showed a similar rule with PU-CS sponge,but the degradation rate and BSA adsorption capacity decreased.Bacteriostatic experimentsshowed that PU-HTCS3 K sponge had the strongest bacteriostatic effect on Escherichia coli.(3)PEG-CS30 K was prepared by modified epoxidation method,and then the block PEG-CS30K-PU sponge was prepared by mixing PEG with PEG as soft segment.XRD patterns showed that when CS existed in block form in polyurethane structure,there was obvious microphase separation between hard and soft segments;with the increase of PEG-CS30 K ratio,the hydrophilicity of block sponge decreased,and the equilibrium swelling degree decreased significantly;compared with the composite sponge prepared by CS as chain extender,the tensile strength and toughness of block sponge were significantly improved;The BSA adsorption capacity and degradation rate of PEG-CS30K-PU sponge were significantly increased.