Microstructure Analysis and Model Discrimination of Enzyme-Catalyzed Copolyesters

The comonomer sequence distributions were analyzed for a series of poly(ε-caprolactone- co -δ-valerolactone) (PCV) copolymers using 13 C nuclear magnetic resonance (NMR) spectroscopy. The four dyad sequences each showed well-resolved peaks in the NMR spectra that allowed easy quantification of the dyad and triad fractions. Although compositional analysis could not discriminate between terminal and penultimate model copolymerization kinetics, the monomer sequence distributions clearly indicated that the lipase-catalyzed copolymerization proceeds via terminal model kinetics. This NMR analytical tool enables rapid characterization of lipase-catalyzed copolymers.