The living nature of the ring opening polymerization/copolymerization of L-lactide (LA) and ε-caprolactone (εCL) to poly-lactic acid (PLA) and poly-caprolactone (PCL) was investigated. Polymeric materials were prepared with bis-ligated magnesium complexes activated for polymerization with 4-fluorophenol co-catalyst. The resulting materials were analyzed with nuclear magnetic resonance spectrometry (NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Studies into the relationship between percentage conversion and molecular weight of polymers generated by the magnesium initiators were completed. For PLA, a linear relationship suggesting well-controlled polymerization was obtained, while for PCL the curved relationship revealed the effects of trans-esterification on polymer synthesis. Sequential polymerization of εCL and then LA yielded a block copolymer, PCL-b-PLA. The PLA and PCL polymers and copolymers were analyzed with DSC and the temperatures for glass transition, crystallization, and melting were determined.

Elucidation of the living ring opening (co-)polymerization of L-lactide and ε-caprolactone by magnesium initiator complexes

2019 Spring National Meeting

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