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以末端含有炔基的2-十二烷基三硫代碳酸酯-2-甲基-丙酸丙炔醇酯(DMPE)为链转移剂(CTA),2,2′偶氮二异丁腈(AIBN)为引发剂,在N,N-二甲基甲酰胺(DMF)中,利用可逆加成-断裂链转移(RAFT)聚合反应制备了分子链末端带炔基的均聚物聚(N-丙烯酰基-L-缬氨酰甲胺)(PAVMA—C帒CH),然后与叠氮基封端的聚乙二醇单甲醚(MPEG-N3)进行“click”偶合反应,制备具有温敏特性的光学活性嵌段聚合物MPEG-b-PAVMA.利用1H-NMR和体积排阻色谱(SEC)等表征了所合成的均聚物和共聚物的结构和分子量分布.1H-NMR结果表明所合成的嵌段共聚物中MPEG和PAVMA链段的重复单元数分别为115和55.利用紫外分光光度计测试了均聚物及嵌段聚合物的温敏特性,结果表明均聚物和共聚物在水中的低临界溶解温度(LCST)分别为6.5℃和19.5℃.比旋光度测试结果表明,均聚物和共聚物具有旋光性,同时相比于单体,其旋光能力有所降低.圆二色谱法(CD)的测试结果显示,均聚物和嵌段共聚物在220nm和197nm附近分别有一个较弱的正Cotton效应峰和一个较强的负Cotton效应峰,并且在水溶液中主要以无规的二级构象结构存在。
Using 2-dodecyltrithiocarbonate-2-methylpropionate (DMPE) with alkynyl as the chain transfer agent (CTA), 2,2’-azobisisobutyronitrile (AIBN) as initiator in N, N-dimethylformamide (DMF) by means of reversible addition-fragmentation chain transfer (RAFT) -acryloyl-L-valylmethylamine) (PAVMA-C 帒 CH) followed by a “click” coupling reaction with azide-terminated polyethylene glycol monomethyl ether (MPEG-N3) Temperature-sensitive optically active block polymer MPEG-b-PAVMA.The structure and molecular weight distribution of the synthesized homopolymers and copolymers were characterized by1H-NMR and size exclusion chromatography (SEC) .1H-NMR results Indicating that the number of repeat units of MPEG and PAVMA segments in the synthesized block copolymer are respectively 115 and 55. The thermosensitive properties of homopolymers and block polymers were tested by UV spectrophotometer and the results showed that the homopolymer and The lower critical solution temperature (LCST) of the copolymer in water was 6.5 ℃ and 19.5 ℃, respectively.The results of specific optical rotation showed that the homopolymers and copolymers have optical rotation and the optical rotation ability is lower than that of the monomers . The results of two-color chromatography (CD) showed that the homopolymers and block copolymers have a weaker positive cotton effect peak and a stronger negative cotton effect peak near 220 nm and 197 nm, respectively, Random secondary conformation exists.