The mechanism for the ring-opening polymerization of ε-caprolactone is presented here with an aluminum-centered catalyst featuring a tridentate ligand and two alkoxide initiating ligands. The addition of electron-withdrawing groups on the tridentate ligand lowers the activation energy of the reaction by increasing the electrophilicity of the central Aluminum. Analysis of the second coordination of a caprolactone confirms experimental results showing a low dispersity of the resulting polycaprolactone. The coordination geometry of the second monomer addition favors a position close to the polymer chain, making it just as likely that the polymer chain will continue to build instead of initiation by the second alkoxide. Additionally, the bond between the Al center and the polymer chain is weaker than the bond between the Al and the second alkoxide, making insertion of the chain into the second monomer energetically favorable compared to insertion of the second alkoxide. Both trends support the conclusion that one initiating ligand is primarily involved in the ring-opening polymerization of caprolactone when using this specific set of a catalysts.    <br/>

Computational investigation of the ring-opening polymerization of ε-Caprolactone and the low dispersity of the polycaprolactone

2019 Spring National Meeting

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