Highly Active Neodymium Catalysts for Polymerization of Dienes and Vinyl Monomers

德克萨斯大学达拉斯分校的Mihaela C. Stefan教授得到化学系化学催化项目的支持，开发基于钕（Nd）金属配合物的聚合催化剂。目的是为研究实验室和化学工业提供一种替代著名的Ziegler-Natta （ZN）催化剂体系的方法，该催化剂体系广泛用于工业上从小分子制备聚合物（大的多单元分子）。提出的基于nd的催化系统具有从不寻常的起始材料生产聚合物的优势，其反应能力超出了当前ZN催化剂的能力。钕基催化体系的多用途性质提高了从不同类别的小有机化合物合成立体规则（高度有序）聚合物的成功可能性。如果成功，该项目可能会立即对聚合物材料的商业生产产生影响，如弹性体、粘合剂和人造纤维。参与该项目的学生将接受有机和聚合物合成以及产品表征技术方面的培训。女高中生有机会参加暑期研究，在化学实验室环境中获得技能。本研究的目的是开发一种由NdCl3和磷酸盐配体组成的新型催化体系，用于聚合各种单体，如二烯、苯乙烯和极性乙烯基单体。将对这些聚合进行机理研究，以了解每种组分的功能，并优化反应条件，以生产具有高立体规则性和明确分子量的聚合物。钕金属中心周围磷酸配体的变化预计会影响合成聚合物的立体规则性、分子量和多分散性。测定了合成钕催化剂的晶体结构，并与催化剂的催化活性进行了对比。这些催化剂用于二烯与极性乙烯基单体的共聚，证明了钕催化体系的多功能性。聚合极性乙烯基单体的能力尤其吸引人，因为传统的齐格勒-纳塔催化剂对极性乙烯基单体的聚合没有活性。

Professor Mihaela C. Stefan of the University of Texas at Dallas is supported by the Chemical Catalysis Program of the Division of Chemistry to develop polymerization catalysts based on neodymium (Nd) metal complexes. The objective is to provide research laboratories and the chemical industry with an alternative for the well-known Ziegler-Natta (ZN) catalyst system, which is widely used in industry for the preparation of polymers (large multi-unit molecules) from smaller molecules. The proposed Nd-based catalytic systems have the advantage of producing polymers from unusual starting materials, in reactions that are beyond the capabilities of current ZN catalysts. The versatile nature of the Nd-based catalytic system enhances the likelihood of success for the synthesis of stereoregular (highly ordered) polymers from different classes of small organic compounds. If successful, the project is likely to have immediate impact on the commercial production of polymeric materials, such as elastomers, adhesives and man-made fibers. Students working on the project are trained in organic and polymer synthesis and product characterization techniques. Female high school students are given the opportunity to participate in summer research to gain skills in a chemistry laboratory environment.The objective of this research is to develop a novel catalytic system composed of NdCl3 and phosphate ligands for the polymerization of a variety of monomers, such as dienes, styrene and polar vinyl monomers. A mechanistic investigation of these polymerizations will be conducted to understand the function of each component and to optimize the reaction conditions for the production of polymers with high stereoregularity and well-defined molecular weights. The variation of the phosphate ligands around the Nd metal center is expected to influence the stereoregularity, molecular weights, and polydispersities of the synthesized polymers. The crystal structures of the synthesized neodymium catalysts is determined and correlated with their catalytic activity. The use of these catalysts for copolymerization of dienes with polar vinyl monomers demonstrates the versatility of the neodymium catalytic systems. The ability to polymerize polar vinyl monomers is especially attractive because the conventional Ziegler-Natta catalysts are not active for polymerization of polar vinyl monomers.