CONTROL OF POLYMERIZATION BY LANTHANOID COMPLEX

聚合反应的控制是高性能、功能性高分子材料分子设计的基础和实践课题。我们对铝卟啉作为极性乙烯基单体加成聚合和杂环单体开环聚合的优良引发剂进行了广泛的研究，得到了分子量分布较窄的聚合物。本研究旨在研究类镧金属卟啉配合物作为聚合引发剂的行为。首先，考察了结构简单的类镧醇氧化物作为引发剂对异氰酸酯和烯酮等异聚物的聚合活性。结果表明，类镧醇氧化物如异丙酸镧（III）可有效聚合烷基异氰酸酯，得到具有高分子量的1-尼龙结构聚合物。镧系烷氧化物对二乙基烯的聚合也有效，使聚合物具有高分子量的聚酯结构。另一方面，试图合成和分离类镧卟啉都没有成功，可能是因为类镧金属离子半径大，卟啉配合物不稳定。

Control of polymerization reaction is a subject of primary importance for molecular design of high performance and functional polymer materials in both fundamental and practical aspects. We have made extensive studies on aluminum porphyrins as excellent initiator for addition polymerization of polar vinyl monomers and ring-opening polymerization of heterocyclic monomers to give the polymers with narrow molecular weight distribution. The present research intended to investigate the behavior of porphyrin complexes of lanthanoid metals as polymerization initiator. First, the activity of lanthanoid alkoxide with simple structure was examined as initiator for the polymerization of heterocumulenes such as isocyanate and ketene. As the result, lanthanoid alkoxide such as lanthanum (III) isopropoxide was found effective for the polymerization of alkyl isocyanates, to give the polymers of 1-nylon structure with very high molecular weights. Lanthanoid alkoxide was found also effective for the polymerization of diethylketene to give the polymer of polyester structure with high molecular weight. On the other hand, attempted synthesis and isolation of lanthanoid porphyrins were not successful, probably because the porphyrin complexes were unstable due to the large ionic radii of lanthanoid metals.