Development of New Synthetic Methodology for Polymers with Controlled Molecular Weight Using Metalloporphyrins as Initiators

本研究以金属卟啉为引发剂，发展了一种新型的、可广泛应用的分子量可控聚合物的合成方法。铝卟啉是典型的引发剂，它能有效地引发环氧化物、内酯、丙交酯等杂环单体和甲基丙烯酸酯、丙烯酸酯、甲基丙烯腈等乙烯基单体的活性聚合，得到分子量可控、分子量分布窄的聚合物。环氧化物与二氧化碳或环酐的活性交替共聚合也是可能的，使用铝卟啉作为与季鎓盐偶联的引发剂。机理研究表明，所有这些聚合反应都在中心铝上进行。引发剂的原子轴向配体键。值得注意的是，卟啉配体的光激发显著地加速了上述聚合反应。 ...更多信息 和可见光。N-取代卟啉锌配合物对环氧化物和环硫化物（三元环硫醚）的活性聚合也是有效的，前者为可见光诱导的活性聚合提供了一个新的例子。利用金属卟啉作为活性聚合引发剂的广泛适用性，已经合成了具有均匀的、可控的嵌段长度的各种嵌段共聚物。进一步值得注意的是发现了新的概念，不朽聚合，其在不朽聚合能够合成具有窄分子量分布的聚合物且聚合物分子的数目多于引发剂分子的数目的意义上上级于活性聚合。不朽聚合对于具有均匀分子量的末端官能（末端反应性、末端可聚合、遥爪和星形）聚合物和低聚物的分子设计是非常有效的。除了铝和锌卟啉之外，锰卟啉也是有效的环氧化物不灭聚合的引发剂。少

The present research project has developed a novel, widely applicable synthetic methodology for polymers with controlled molecular weight by using metalloporphyrins as initiators. Aluminum porphyrins are the representative initiator, which bring about effectively the living polymerizations of heterocyclic monomers such as epoxides, lactones and lactide, and vinyl monomers such as methacrylic and acrylic esters and methacrylonitdle, affording the polymers of controlled molecular weight with narrow molecular weight distribution. Living, alternating copolymerizadon of epoxides with carbon dioxide or cyclic anhydride is also possible using aluminum porphyrin as initiator coupled with quaternary onium salts. Mechanistic studies have demonstrated that all these polymerizations proceed at the central aluminum. atom axial ligand bond of the initiator. It should be of interest to note that some of the above polymerizations are dramatically accelerated by the photoexcitation of the porphyrin lig … More and with visible light. Zinc complexes of N-subsdtuted porphyrins are found also effective for the living polymerizations of epoxides and episulfides (three-membered cyclic thioethers), where the former case has provided a novel example of visible light-induced living polymerization. By taking advantage of the wide applicability of metalloporphyrins as initiators for living polymerizations, a variety of block copolymers with uniform, controlled block lengths have been synthesized. Of further interest to note is a discovery of the new concept, immortal polymerization, which is superior to living polymerization in the sense that immortal polymerization enables the synthesis of polymers with narrow molecular weight distribution with the number of the polymer molecules more than that of the initiator molecules. Immortal polymerization is very effective for molecular design of terminally functional (end-reactive, end-polymerizable, telechelic, and star-shaped) polymers and oligomers with uniform molecular weights. In addition to aluminum and zinc porphyrins, manganese porphyrins are also effective as initiators for the immortal polymerization of epoxides. Less