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Efficient Construction of Macromolecular Loop and Study on Its Dynamics

大分子环的高效构建及其动力学研究

基本信息

批准号：
18350058
负责人：
OIKE Hideaki
金额：
$ 11.02万
依托单位：
Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Cyclic macromolecular architectures have gained increasing interests in fundamental polymer chemistry due to its closed loop topology, i.e., absence of chain ends. The lack of the excess mobility conferred by the chain ends of a cyclic polymer is believed to affect its solution and bulk properties. A typical synthetic procedure for cyclic polymers is a ring-closing reaction of an end-functional polymer precursor under dilution. However, a development of an effective polymer cyclization reaction has still been an ongoing challenge. In this study, we have synthesized cyclic and 8-shaped polystyrenes through the metathesis condensation reaction of linear and 4-armed star-shaped polystyrenes having olefinic end groups, respectively, in the presence of Grubbs catalyst. The polymer precursors were prepared by living anionic polymerization technique and were employed as a substrate of the metathesis condensation reaction. The obtained cyclic and 8-shaped polystyrenes were unequivocally characterized by means of 1H NMR, size-exclusion chromatography (SEC) and liquid chromatography at critical condition (LCCC) as well as MALDI-TOF MS techniques. Although the metathesis reaction proceeded even under the diluted condition, the reaction concentration should be below 0.2 g/L to obtain the cyclic polystyrenes in 80% selectivity, which is rather good but comparable to some conventional methods. Thus, the further investigation of an efficient cyclization system should be continued to provide an enough amount of a cyclic polymer sample for a study of polymer dynamics as well as microscopy analysis.

环状大分子结构由于其闭环拓扑结构，即，没有链端。认为环状聚合物的链端所赋予的过量流动性的缺乏影响其溶液和本体性质。环状聚合物的典型合成程序是末端官能聚合物前体在稀释下的闭环反应。然而，开发有效的聚合物环化反应仍然是一个持续的挑战。在这项研究中，我们已经合成了环状和8-形聚苯乙烯通过易位缩合反应的线性和4-臂星形聚苯乙烯具有烯烃端基，分别在Grubbs催化剂的存在下。通过活性阴离子聚合技术制备了聚合物前驱体，并将其用作复分解缩合反应的底物。所得的环状和8-形聚苯乙烯明确地通过1H NMR，尺寸排阻色谱法（SEC）和液相色谱在临界条件下（LCCC），以及MALDI-TOF MS技术进行了表征。尽管复分解反应甚至在稀释条件下进行，但反应浓度应低于0.2g/L以80%的选择性获得环状聚苯乙烯，这是相当好的，但与一些常规方法相当。因此，应继续对有效的环化体系进行进一步研究，以提供足够量的环状聚合物样品用于聚合物动力学研究以及显微镜分析。