Self-assembly and Its Structure of a High-molecular Amphiphilic Compounds

本项目的目标是制备一种两端带有环氧乙烷链的低聚丙烯的非离子两亲性三嵌段共聚物，并研究其自组织能力。该产品的第一个关键步骤是建立一种有效的方法来制备具有高端亚甲基官能度的遥螺旋低聚丙烯。实验结果表明，由于原始聚丙烯的相对分子质量较高，且遥螺杆也是从高含量PP的塑料废料中得到的，官能度足够高，接近2。下一步是通过氢硼化反应对遥螺型低聚丙烯进行羟基化。对于以上得到的OP样品，该反应几乎是定量实现的。间同构型OP的反应性高于等同构型OP，可能是由于结晶度不同所致。最后，在甲醇钠催化下，环氧乙烷(EO)在OP的羟基上开环聚合，成功地得到了三嵌段共聚物。经溶剂萃取法和凝胶渗透色谱分离，得到了一种两亲性高分子化合物，其质量分数为：Mn~2000，MW/Mn~1.1，OP/EO摩尔比为1/1.4。结果表明，该化合物在水介质中具有表面活性，临界胶束浓度接近0.002 g/L，聚集体平均半径约为150 nm。这一结果表明，胶束聚集体随着浓度的增加而增长，扫描电子显微镜观察到形成了具有中心空洞的囊泡状聚集体。

The objective of this project is to prepare a nonionic amphiphilic triblock copolymer of oligopropylene having ethylene oxide chains of both the ends and to investigate its ability for self-organization. The first key-step in this product is to establish an effective method for preparation of telechelic oligopropylene with a high functionality of end-vinylidene groups. The experimental results show that the functionality is adequately high and approaches 2, as the molecular weight of original polypropylene is higher, and the telechelics are also obtained from the waste of plastics including high contents of PP.The next step is the hydroxylation of telechelic oligopropylene (OP) by hydroboration. This reaction was achieved nearly quantitatively for the OP samples obtained above. The reactivity of syndiotactic OP is higher than that of isotactic OP, probably owing to the difference in degree of crystallinity. The micro-structure of the hydroxylated OP was examined in detail by NMR.Finally, the ring-opening polymerization of ethylene oxide (EO) onto the hydroxyl group of OP using sodium methoxide as a catalyst affords successfully the triblock copolymer as the final product of this research. After fractionations by solvent extraction and subsequently by GPC, a high-molecular amphiphilic compound of Mn 〜2000, Mw/Mn 〜1.1, and molar ratio of OP/EO of 1/1.4 was obtained. It was confirmed that this compound shows surface activity in aqueous media ; the critical micelle concentration is near 0.002 g/l and the average radius of aggregates is about 150 nm. This result suggests that the micellar aggregates grow as the concentration becomes higher and the observation by SEM shows the formation of vesicle-like aggregates with central cavities.