Ligand and Catalyst Designs for Stereocontrolled Ring Expansion Polymerization Reactions

佛罗里达大学的Adam S.Veige教授得到化学系化学催化计划的支持，开发用于合成环状聚合物的催化剂，环状聚合物是一类由于其环状结构而不是线性结构产生的独特性质而日益受到基础和工业关注的聚合物。该项目的重点是开发基于丰富的过渡金属和特殊设计的配体的催化剂。我们的目标是开发优化的催化剂，不仅能高效和选择性地产生环状聚合物，而且能以非常规则的方式进行聚合。不含线性杂质的环状聚合物非常适用于特殊的工业应用，例如减震复合材料的组件以及发动机和喷气发动机油。在进行这项研究的过程中，学生们在无机、有机金属、聚合物和材料化学方面发展跨学科技能，以满足日益专业化的技术工作场所的需求。该项目继续开展教育推广计划，最终在橡树购物中心举办一年一度的催化化学日活动。该活动旨在提高公众对催化研究的认识和重要性，并激励下一代科学家。开发了基于富含过渡金属与三、四阴离子钳形配体的络合物的催化剂。探索了用这些催化剂制备环状聚合物的独特方法。亚烷基和链烷基催化剂是用于环烯的立体定向扩环歧化聚合(REMP)和用于烯烃聚合生成大环多炔的催化剂。配体和催化剂的设计是基于基本的电子/结构性质关系。聚合物的相对分子质量的控制是通过调节配体的性质来实现的，以产生快速的引发物种。这些产品是不含线性杂质的环状聚合物，非常适合各种应用，如减震复合材料的组件以及电机和喷气发动机油。

Professor Adam S. Veige of the University of Florida is supported by the Chemical Catalysis program of the Division of Chemistry to develop catalysts for the synthesis of cyclic polymers, a class of polymers which is growing in fundamental and industrial interest due to the unique properties resulting from their cyclic, rather than linear, structure. The focus of this project is on the development of catalysts based on abundant transition metals and specially designed ligands. The objective is to develop optimized catalysts that not only produce cyclic polymers efficiently and selectively, but also execute the polymerization in a very regular fashion. Cyclic polymers which are free from linear impurities are highly desirable for special industrial applications, such as components of shock-mitigating composite materials and motor and jet engine oils. During the course of conducting this research, students develop cross-disciplinary skills in inorganic, organometallic, polymer and material chemistry to meet the demands of an increasingly specialized technological workplace. The project continues the educational outreach program that culminates in an annual Center for Catalysis-Chemistry Day at the Oaks Mall. The event is intended to raise public awareness of research in and the importance of catalysis and to inspire the next generation of scientists. Catalysts based on complexes of abundant transition metals with tri- and tetra-anionic pincer ligands are developed. Unique approaches to preparing cyclic polymers with these catalysts are explored. Alkylidyne and tethered alkylidene catalysts are developed for the stereospecific ring expansion metathesis polymerization (REMP) of cyclic alkenes and for the polymerization of alkynes to produce macrocyclic polyalkynes. The design of ligands and catalysts is based on fundamental electronic/structure property relationships. Control of the molecular weight of the polymers is accomplished by tuning ligand properties to create rapidly initiating species. The products, cyclic polymers which are free from linear impurities, are highly desirable for a variety of applications, such as components of shock-mitigating composite materials and motor and jet engine oils.