DESIGN OF POLYMERIC MICROSPHERES USING MACROMONOMERS

本研究旨在利用两亲性大分子单体设计合成高分子微球。聚（环氧乙烷）（PEO）和聚（甲基丙烯酸）（PMA）的大分子单体携带苯乙烯基或甲基丙烯酸酯端基，疏水性增强的亚烷基间隔，是合理的预期和事实上发现作为有效的，反应性（可共聚）乳化剂和分散剂在水和醇介质中的疏水单体的乳液分散聚合。因此，大分子单体与共聚单体共聚以原位产生接枝共聚物，接枝共聚物的支链覆盖颗粒表面以实现空间稳定，而主干用作颗粒中的锚。本研究提出了这种空间稳定聚合物粒子形成的基本机理和理论，并将其应用于各种使用PEO和PMA大分子单体的乳液和分散体系，建立了一个基本的指导原则， ...更多信息 ne的微球，设计，主要结论如下。(1)在苯乙烯和甲基丙烯酸丁酯的甲醇-水分散聚合中，PEO大分子单体有效地得到了亚微米至微米级的单分散微球。一个理论的粒度控制，基于空间稳定的接枝共聚的大分子单体链覆盖在表面上，合理地占实验的大小变化，根据1/3阶的转化，2/3阶的共聚单体浓度，和-1/2阶的大分子单体浓度。接枝PEO链从无规卷曲到延伸构象的变化也通过NMR测量证实。(2)PEO和PMA大分子单体在苯乙烯的乳液聚合中也是有效的。对传统的乳液聚合理论进行了修正，使其不仅考虑了大分子单体的乳化作用，还考虑了大分子单体的共聚作用。(3)非常快速聚合的PEO大分子单体在水中进行了研究，动力学通过使用ESR等，归因于它们的胶束形成。该梳形聚合物在水中可以被描述为一个半柔性的蠕虫状链，就像一个带有硬的，疏水的聚苯乙烯轴的瓶刷，具有无数的软的，可溶的PEO头发，将发挥广泛的排斥体积效应。少

This research project aimed at designed synthesis of polymeric microspheres by taking advantage of amphiphilic macromonomers. Poly (ethylene oxide) (PEO) and poly (methacrylicacid) (PMA) macromonomers carrying stryl or methacrylate end groups, hydrophobically enhanced by alkylene spacers, are reasonably expected and in fact found to work as effective, reactive (copolymerizable) emulsifiers and disperants in emulsion dispersion polymerizations of hydrophobic monomers in water and alcoholic media. Thus the macromonomers copolymerized with the comonomers to produce in situ the graft copolymers, the branches of which cover the particle surfaces to effect steric stabilization while the trunks serve as the anchors into the particles. This project has proposed a basic mechanism and theory of the formation of such sterically-stabilized polymeric particles and has applied the theory to various emulsion and dispersion systems using the PEO and PMA macromonomers to establish a fundamental guideli … More ne to the microspheres, design, with the main conclusions as follows.(1) The PEO macromonomers effectively afforded monodisperse microspheres of submicron to micron size in dispersion polymerization of stirene 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.(2) PEO and PMA macromonomers were also effective in emulsion polymerization of stirene. 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.(3) Very rapid polymerization of the PEO macromonomers in water was studied kinetically 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 bottle brush with a hard, hydrophobic polystirene axle with an uncountable number of soft, soluble PEO hairs which will exert an extensive excluded-volume effect.To summarize, the macromonomer technique for design of polymeric microspheres is relatively simple both in principle and in practice, promising a variety of applications. Less