Lipase-Catalyzed Ring-Opening Copolymerization of
ε‑Caprolactone and β‑Lactam
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Abstract
The enzymatic ring-opening copolymerization
of ε-caprolactone
(ε-CL) and β-lactam by using Candida antarctica lipase B (CAL-B) as catalyst was studied. Variation of the feed
ratios of 25:75, 50:50, and 75:25 of ε-CL/β-lactam was
performed. The products contain poly(ε-CL-<i>co</i>-β-lactam) and the homopolymers of poly(ε-CL) and poly(β-lactam).
The structure of the copolymers was determined by MALDI-ToF MS. Poly(ε-CL-<i>co</i>-β-lactam) has an alternating and random structure
consisting of alternating repeating units with oligo(ε-CL) or
oligo(β-lactam). The highest fraction of the alternating copolymers
resulted from the reaction with a feed ratio 50:50. The copolymer
is a semicrystalline polymer with a <i>T</i><sub>m</sub> at 124 °C and <i>T</i><sub>g</sub>s at −15
and 50 °C. Interestingly, the copolymer also demonstrated cold
crystallization at 29 and 74 °C, after quenching the sample from
the melt in liquid nitrogen
