Ligand and Catalyst Designs for Stereocontrolled Ring Expansion Polymerization Reactions

University Of Florida, Gainesville FL

Investigators

Abstract

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.