Sustainable alternatives to polymers made from petrochemical materials are a growing need, and polyesters from bio-derived lactones serve as promising substitutes due to their degradability. However, to make sustainable polymers competitive with industrially relevant petrochemical plastics, it is necessary to understand the fundamental aspects of the ring-opening polymerization (ROP) by which these materials are made. Previously, it has been found that altering ROP catalyst parameters such as electronics, sterics and flexibility of the surrounding ligand framework has an effect on the rate of polymerization. Specifically, salen-Aluminum catalysts have been studied extensively within the context of this work, due to their ability to produce high molecular weight polymers while maintaining polymerization control. Even more, their moderate polymerization rates allow for facile kinetic monitoring via techniques such as NMR spectroscopy. While a variety of catalyst alterations have been explored for these complexes, mononuclear catalysts with increased flexibility (i.e. backbones containing &gt; 3 carbons) have not been thoroughly investigated. As such, the aim of this work is to synthesize salen-Aluminum catalysts with four and five carbon backbones and understand their capabilities for ROP. While making mononuclear species proved a challenge, synthesis and complete characterization of several catalysts were completed. Even more, their ROP reactions toward racemic lactide (<i>rac</i>-LA, a sustainable lactone) under various conditions were accomplished and the subsequent polymers analyzed.

Understanding catalyst flexibility and its effect on the ring-opening polymerization of cyclic esters

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.