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

在乙烯基单体的阳离子聚合中，“水中阳离子聚合”和“立体定向阳离子聚合”一直被认为是非常困难的。通过设计路易斯酸作为控制碳正离子生长的催化剂，这两个目标都实现了。2年的研究成果总结如下：(A)水中阳离子聚合。通常，阳离子聚合在水中是不可能进行的，因为生长的碳正离子和催化剂（路易斯酸）很容易失活。本研究发现稀土金属三氟甲烷磺酸盐（三氟磺酸盐）及其相关化合物具有耐食性，可用于阳离子聚合。(a)对烷氧苯乙烯在水中的阳离子聚合；(1)对甲氧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)水中聚合物分子量的精密控制。(b)用三氟化硼/醇引发体系在乙腈水溶液中直接聚合“无保护”对羟基苯乙烯；2)单体嵌段共聚物和无规共聚物的精密合成。(B)立体定向阳离子聚合立体调控是阳离子聚合中的另一个难题。本研究针对这一领域设计了刘易斯酸，并实现了以下结果：(a)异丁基和异丙基乙烯醚与双苯氧基二氯化钛在-78℃非极性介质中高度等特异性聚合；等等性> 90%。(b)烷基乙烯醚与具有长烷基取代基的磷酸的等特异性阳离子聚合。

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.