Jianping Sun

Enhanced copper-catalyzed “click” reaction between homopolymers with terminal azide and alkyne groups in the presence of water

Abstract We report here that the efficiency of the click chemistry between the terminal azide and alkyne groups of different polymer chains could be drastically increased with the addition of an optimum amount of water into a reaction system. That is, the efficiency was only slightly promoted by the addition of a small amount of water into the reaction mixture. However, the reaction efficiency was increased dramatically near the water volume fraction to lead the reaction mixture into nanosized phase separation. Further increasing in water content caused the polymer(s) to undergo macroscopic phase separation and the click reaction efficiency was decreased once again. The enhanced efficiency of click coupling reaction including conversion and rate was also demonstrated via in-situ 1H-NMR. The reaction kinetics as well as reaction rate constant for these reaction system with typical water content were also evaluated. This finding on enhanced click reaction is of practical value, because click reactions in polymer synthesis are generally more difficult to be carried out and proceed relative slowly at low yield in most case because of the strong steric hindrance effect from “large and long” polymer chains, as compared to “click” reactions which are employed for preparation of the low molecular weight organic compounds.

SYNTHESIS AND SELF-ASSEMBLY BEHAVIORS OF BLOCK COPOLYMER A- b -(B- r -C) BEARING RANDOM COMPONENTS: SYNTHESIS AND SELF-ASSEMBLY BEHAVIORS OF BLOCK COPOLYMER A- b -(B- r -C) BEARING RANDOM COMPONENTS

通过原子转移自由基（ATRP）方法合成了其中一个嵌段是由2种单体无规共聚的两嵌段聚合物——聚丙烯酸肉桂酸乙酯-b-（聚苯乙烯-r-聚丙烯酸叔丁酯）,（记为PCEA-b-（PtBA-r-PS））.讨论了聚合过程中影响分子量分布以及分子量控制的各种因素.通过氢核磁（1H-NMR）确定各嵌段的重复单元数分别为50,111,138.通过透射电镜（TEM）观察,研究了该嵌段聚合物在选择性溶剂1-氯癸烷以及环戊烷中的自组装行为,发现该嵌段聚合物在环己烷中直接分散可以形成有聚集倾向的短棒状或球形胶束,而在1-氯癸烷中直接分散得到的胶束,在膜表面随着1-氯癸烷溶剂的缓慢挥发可以组装得到具有规则微纳结构的相互连接的柱状胶束.