The Preparation Of CO₂-responsive Photo-polymerization Chitosan Microspheres

CO2 responsive polymer is a popular intelligence polymer in recent years.CO2 is a kind of cheap,abundant,natural and non-toxic gas.Because CO2 can trigger the responsive polymers,CO2 stimululi-response polymer has a great potential for application in many fields.Chitosan is the only natural alkaline polysaccharide in nature,which has pH sensitivity,biocompatibility,low toxicity and biodegradability.Due to these good biological characteristics,the application of chitosan and its derivatives in drug delivery has attracted much attention.The most important is the primary amino group on the chitosan unit can react with CO2.Moreover,photopolymerization has the characteristics of short polymerization time,environment-friendly and efficient.Therefore,the purpose of this paper is to combine the advantages of chitosan?CO2 stimululi-response polymer and photopolymerization.The chitosan is modified to form a chitosan derivative which can response with CO2 and photopolymerization,and then a special method will be used to prepare microspheres.It can be used for drug delivery,and the synthetic polymers and microspheres were studied in many properties.1.The water-soluble poly(ethylene glycol)chitosan with different amino content were synthesized,and their structure and amino content were determined.2.The CO2 stimululi-responsive properties of poly(ethylene glycol)chitosan were tested and verified by thermal weight loss analysis,viscosity change and liquid solid transformation.It is proved that the poly(ethylene glycol)chitosan possess good CO2 reversible response property,and the response time was shorter with the increase of amino content.3.Double bonds were introduced into poly(ethylene glycol)chitosan with different contents,and the changes in the storage modulus and loss modulus of the products before response with CO2,after response with CO2 and after photopolymerization were investigated respectively.The results showed that the storage modulus and loss modulus of the products greatly increased after the CO2 response,and further enhanced after photopolymerization.4.Thourgh the CO2 reversible response property,the microspheres were prepare with endproducts,by the dual channel microinjection pump,and their particle size,swelling and porosity were investigated.5.The application of the endproducts in imprint was expllored,in which the pattern on the template can accurately produced and erased upon CO2 stimululi-response with good cyclbility.What is more,the pattern can be permanent preserved after photopolymerization.6.Selected 5-fluorouracil as a model drug,the drug release performance of three kinds of micro spheres with different double bond content were investigated.The results showed that the three kinds of microspheres can release drugs slowly after the initial 2-3h sudden release stage.With the increase of the double bond content,the longer drug release time achieved,and the longest drug release completely time was up to 28h.