Living Polyisonitrile Polymerization Catalysts

在有机动力学项目的支持下，诺瓦克博士将 研究设计、准备和实施 有机金属催化剂的“活性”聚合 已知单体产生稳定的螺旋聚合物。具体地说， 新型Ni（I）和Ni（II）催化剂用于聚合 将研究异腈。详细的机制研究 将努力提供信息， 需要对这些新催化剂进行改性， 应用.诺瓦克博士研究的基本前提是， 有机金属配合物，具有多种配位 球和氧化态，可以用来改变 聚合物端基的反应性以可预测的方式， 高度的精确度。根据以下要求， 在特定的反应中，有机金属物质可以是 被要求激活或钝化聚合物 端基诺瓦克博士的研究旨在提供一种方法， 其端基可以对所有过程不起反应， 除了期望的引发和传播步骤之外， 导致聚合物形成。 %%% 用于可控聚合的最终聚合催化剂 定义明确的大分子的合成是“活的”。生活 聚合可用于合成大分子， 预定分子量，窄链长 分布和定义的端基。此外，生活 系统允许精确合成“嵌段共聚物”， 它提供了一个组合的属性无法获得从 简单的聚合物共混物或无规共聚物。诺瓦克医生会 利用这种方法来控制聚异， 腈是一类重要的可溶性聚合物。此外，本发明还提供了一种方法， 他的方法的生命本质将被利用在 制备新型二嵌段和三嵌段共聚物， 作为一类新热塑性弹性体而受到关注。

With support from the Organic Dynamics Program, Dr. Novak will investigate the design, preparation, and implementation of organometallic catalysts for the "living" polymerization of monomers known to yield stable, helical polymers. Specifically, new Ni(I) and Ni(II) catalysts for the polymerization of isonitriles will be investigated. Detailed mechanistic studies will be performed in an effort to provide the information necessary to modify these new catalysts for specific applications. The basic premise of Dr. Novak's study is that organometallic complexes, which possess versatile coordination spheres and oxidation states, can be used to alter the reactivity of polymer endgoups in a predictable manner and with a high degree of precision. Depending upon the requirements of the particular reaction, the organometallic species may be called upon to either activate or deactivate the polymer endgroup. Dr. Novak's study is designed to provide a means by which endgroups can be rendered unreactive toward all processes other than the desired initiation and propagation steps that lead to polymer formation. %%% The ultimate polymerization catalysts for the controlled synthesis of well-defined macromolecules are "living". Living polymerizations can be used to synthesize macromolecules with pre-determined molecular weights, narrow chain-length distributions, and defined endgroups. In addition, living systems allow the precise synthesis of "block copolymers", which offer a combination of properties unobtainable from simple polymer blends or random copolymers. Dr. Novak will utilize this approach for controlled synthesis of polyiso- nitriles, an important class of soluble polymers. In addition, the living nature of his approach will be exploited in the preparation of novel di- and tri-block copolymers, which are of interest as a new class of thermoplastic elastomers.