CAREER: Iron Polymerization Catalysis for the Synthesis of High Performance Degradable Polymers

Boston College, Chestnut Hill MA

Investigators

Abstract

In this project funded by the Chemical Catalysis program of the Chemistry Division, Professor Jeffery A. Byers of Boston College is developing methods to convert chemicals made from renewable feedstocks, such as corn and soybean oil, into biodegradable plastics with a wide range of properties. These methods are based upon using catalysts to accomplish chemical conversions, and the particular catalysts being developed are based upon a low toxicity, earth abundant element, iron. The catalysts are able to make plastics with new structures and compositions that are expected to display improved physical properties. To increase awareness of the need for new, sustainable materials and to promote the participation of under represented minorities in STEM fields, Professor Byers is developing, testing and disseminating a set of experiential demonstrations for teaching K-9 students about the scientific method as well as catalysis and polymers. Professor Byers is also working on a "Paper to Plastics" workshop experience for high school students to discover how sustainable materials can be prepared. In this project, Professor Byers is studying bis(imino)pyridine-bisalkoxide complexes of iron as catalysts for the polymerization of D,L-lactide and epoxides. While in the +2 oxidation state the complexes catalyze the polymerization D,L-lactide but not epoxides and in the +3 oxidation state the complexes catalyze the polymerization of epoxides but not D,L-lactide. Thus, redox chemistry or electrochemistry is being explored to switch the catalyst between two different modes of reactivity, and this property of the catalyst is being exploited for the synthesis of multiblock copolymers between epoxides and lactide as well as the development of a redox-triggered crosslinking reaction. Termination chemistry is being explored that will link the two growing polymer chains on each metal center. These polymer structure modifications are expected to result in biodegradable polymers with properties that are unique compared to currently used biodegradable polymers. The broader impacts of the project pertain to the potential uses of redox switching to mediate orthogonal reactivity in catalysis, the usefulness of sustainable materials, and the planned educational activities.