DESIGN AND APPLICATION OF AMPHIPHILIC ORGANIZED POLYMERS BY POLYMERIZATION OF SUFACE-ACTIVE MONOMERS

本研究项目旨在利用两亲性大单体的优势来设计两亲性有序聚合物。合成了聚环氧乙烷(PEO)和聚甲基丙烯酸(PMA)大分子单体，通过亚烷基间隔基的疏水增强，制备了端基为苯乙烯或甲基丙烯酸酯的大单体。这些大单体在水中聚合非常迅速，形成具有疏水主干和亲水支链的规则梳状聚合物，并在水或酒精介质中与疏水单体共聚，得到亚微米到微米尺寸的可控聚合物微米级。本项目揭示了这些两亲性大单体在水中胶束聚合的基本机理，规整和密集支化的梳状聚合物的构象表征，以及使用两亲性大单体设计聚合物微球的基本指导方针。主要结论如下：(1)利用…研究了聚氧化乙烯大单体在水中的快速聚合更多的是通过使用ESR等手段，归因于它们的胶束形成。在水中形成的梳状聚合物可以描述为半柔性的蠕虫链，就像带有硬的疏水聚苯乙烯轴的瓶刷一样，具有大量柔软的、可溶的PEO毛发，将发挥广泛的排除体积效应。(2)PEO大单体有效地提供了亚微米到微米尺寸的单分散微球，用于苯乙烯和甲基丙烯酸丁酯在甲醇-水中的分散聚合。基于表面覆盖的接枝共聚大分子链对空间位阻的稳定作用，提出了粒径控制理论，合理地解释了实验结果：粒径的变化按1/3级的转化率、2/3级的共聚单体浓度和-1/2级的大单体浓度变化。核磁共振测试也证实了接枝的PEO链从无规卷曲变为延伸的构象。(3)PEO和PMA大单体对苯乙烯的乳液聚合也是有效的。传统的乳液聚合理论除了作为乳化剂外，还需要对大单体参与共聚反应进行修正。综上所述，表面活性大单体对于包括规则梳状聚合物和微球在内的两亲性聚合物的设计是有用的，具有广泛的应用前景。较少

This research project aimed at design of amphiphilically organized polymers by taking advantage of amphiphilic macromonomers. Poly(ethylene oxide) (PEO) and poly(methacrylic acid) (PMA) macromonomers carrying styry1 or methacrylate end groups, hydrophobically enhanced by alkylene spacers, were prepared. These macromonomers were found to polymerize very rapidly in water to afford regular comb polymers with hydrophobic trunks and hydrophilic branches, and copolymerize with a hydrophobic monomer in water or alcoholic media to give controlled polymeric microsheres of submicron to micron size. This project has thus disclosed a basic mechanism of micellar polymerization of these amphilic macromonomers in water, conformational characterization of regularly and densely branched comb polymers, and a fundamental guideline to the polymeric microspheres' design using amphiphilic macromonomers. The main conclusions follow.(1) Very rapid polymerization of the PEO macromonomers in water was studied k … More inetically by use of ESR among others, to be ascribed to their micelle formation. The resulting comb polymer in water could be described as a semiflexible wormlike chain just like a bottlebrush with a hard, hydrophobic polystyrene axle with voluminous number of soft, soluble PEO hairs which will exert an extensive excluded-volume effect.(2) The PEO macromonomers effectively afforded monodisperse microspheres of submicron to micron size in dispersion polymerization of styrene and butyl methacrylate in methanol-water. A theory of particle size control, based on the steric stabilization by the graft-copolymerized macromonomer chains covered on the surface, reasonably accounted for the experiments ; the size changes according to 1/3rd order of conversion, 2/3rd order of the comonomer concentration, and -1/2nd order of the macromonomer concentration. Change of the grafted PEO chains from a random coil to an extended conformation was also confirmed by NMR measurement.(3) PEO and PMA macromonomers were also effective in emulsion polymerization of styrene. The traditional theory of emulsion polymerization has to be modified to account for the macromonomers to take part in the copolymerization in addition to function as the emulsifiers.To summarize, the surface-active macromonomers are useful for design of polymeric amphiphiles including regular comb polymers and microspheres, promising a variety of applications. Less