Cationic Polymerization in Water and Stereospecific Cationic Polymerization : Design of Lewis Acid Catalysts and Precision Polymerization Control

本研究旨在开发“水中阳离子聚合”和“立体定向阳离子聚合”，这两种阳离子聚合一直被认为是乙烯基类单体阳离子聚合中的难点。这两个目标都是通过设计Lewis酸作为催化剂来控制不断增长的碳正离子而实现的。这两年的研究成果总结如下：(A)阳离子聚合在水中通常不可能进行阳离子聚合，因为不断增长的碳阳离子和催化剂(Lewis酸)很容易失活。在这项研究中，稀土金属三氟甲基磺酸盐(三氟酸盐)及其相关化合物被发现是耐食性的，可以用于阳离子聚合。(A)对烷氧基苯乙烯在水中的阳离子聚合；(1)对甲氧基苯乙烯和其他单体与稀土金属三氟酸盐和类似的铜或锌衍生物的悬浮聚合；(2)类似催化剂和两亲性化合物的乳液聚合；(3)水中聚合物相对分子质量的精确控制。(B)对羟基苯乙烯的直接活性阳离子聚合。(1)在乙腈水溶液中，“无保护”的对羟基苯乙烯与三氟化硼/醇引发体系的直接聚合；(2)单体嵌段和无规共聚物的精确合成。(B)立体定向阳离子聚合。本研究针对这一领域进行了Lewis酸的设计，并实现了以下结果：(A)异丁基乙烯基醚和异丙基乙烯基醚与二氯二苯氧基钛在-78℃非极性介质中的高等比聚合，等规度为90%。(B)烷基乙烯基醚与具有长取代基膦酸的等比阳离子聚合。

This research is to develop "cationic polymerization in water" and "stereospecific cationic polymerization", both of which have been considered very difficult in cationic polymerization of vinyl monomers. Both objectives have been achieved by designing Lewis acids as catalysts that control the growing carbocations. The achievements of this 2-year research is summarized as follows :(A) Cationic Polymerization in WaterIn general, cationic polymerization is impossible to proceed in water, because the growing carbocation and catalysts (Lewis acids) are readily deactivated. In this study, rare-earth metal trifluoromethanesulfonates (triflates) and related compounds are found to be eater-tolerant and can be used in cationic polymerization. The following have been achieved :(a) Cationic Polymerization of p-Alkoxystyrenes in Water1) Suspension polymerizations p-methoxystyrene and other monomers with rare-earth metal triflates and similar copper or zinc derivatives ;2) Emulsion polymerizations with similar catalysts and amphiphilic compounds ;3) Precision control of polymer molecular weight in water.(b) Direct Living Cationic Polymerization of p-Hydroxystyrene1) Direct polymerization of "unprotected" p-hydroxystyrene with boron trifluoride/alcohol initiating systems in aqueous acetonitrile solvent ;2) Precision synthesis of block and random copolymers of the monomer.(B) Stereospecific Cationic PolymerizationStereoregulation is another difficult subject in cationic polymerization. This study is directed its design of Lewis acids to this area, and achieved the following :(a) Highly isospecific polymerizations of isobutyl and isopropyl vinyl ethers with bisphenoxy titanium dichlorides in nonpolar media at -78℃ ; isotacticity > 90%.(b) Isospecific cationic polymerizations of alkyl vinyl ethers with phosphinic acids with long alkyl substituents.