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通过Diels-Alder(D-A)反应,合成了具有规整化学结构的接枝共聚物,壳聚糖-O-聚乙二醇(CS-O-PEG).D-A反应所需双烯体(呋喃环)通过糠基硫醇与端甲基丙烯酸酯聚乙二醇之间的巯基-丙烯酸酯(thio-acrylate)反应合成得到;马来酰亚胺基丙酸通过活泼酯法偶联到十二烷基硫酸钠-壳聚糖复合物(SCC)羟基上,从而获得亲双烯体.采用红外光谱(FTIR)和核磁共振(1H-NMR)表征了中间产物与最终产物的结构,并用原位核磁监测D-A反应及其逆反应过程.结果表明,聚乙二醇双烯体可在水介质中温和条件下定量接枝到壳聚糖羟基上,反应具有点击特征;同时,聚乙二醇与壳聚糖之间的连接键在高温下(90℃)可通过D-A逆反应而发生断裂.
By Diels-Alder (DA) reaction, the graft copolymer with regular chemical structure and chitosan-O-polyethylene glycol (CS-O-PEG) were synthesized.The diene (furan ring) Was synthesized by the thio-acrylate reaction between furfuryl mercaptan and terminal methacrylate polyethylene glycol; Maleimidopropionic acid was coupled to lauryl Sodium dodecyl sulfate-chitosan complex (SCC) to obtain dienophiles.The structures of the intermediate and the final product were characterized by FTIR and 1H-NMR, and their structures were characterized by in situ nuclear magnetic resonance DA reaction and its reverse reaction process.The results showed that polyethylene glycol diolefin can be quantitatively grafted onto the hydroxyl group of chitosan under mild conditions in an aqueous medium with a click feature and at the same time polyethylene glycol and chitosan The linkages between them can be broken by DA reverse reaction at high temperature (90 ° C).