Materials derived from biomass feedstocks are considered to be suitable and sustainable substitutes for some of the petrochemically-derived products used in commercially relevant polymers. Their ability to be functionalized, yet well-characterized, and their eventual degradation make them ideal alternative materials. An option to synthesize polymers from these feedstocks involves the ring-opening transesterification polymerization (ROTEP) of cyclic esters such as rac-lactide, ultimately yielding renewable, linear aliphatic polyesters. In this work, such ROTEP polymerizations are performed under the utilization of tetradentate zinc complexes comprised of asymmetric salan ligands. These complexes show great potential, as they yield substantially isotactic polymers with relatively narrow polydispersities. Additionally, they polymerize rac-lactide efficiently, reaching p &gt; 95% in as few as five minutes through the utilization of a benzyl alkoxide initiator. Herein, steric and electronic effects on the catalytic framework are examined in order to determine their effects on polymerization rate and the resulting polymer’s physical characteristics. Through analysis of these alterations, the polymerization by these catalytic systems can be better understood, providing new insights for improved, rational catalyst design for future sustainable polymerization reactions.

Analysis of novel tetradentate zinc catalysts used for the polymerization of rac-lactide

253rd National Meeting (2017)

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