Zinc‐Catalyzed Chemical Recycling of Poly(ϵ‐caprolactone) Applying Transesterification Reactions

Abstract The chemical recycling of poly(ϵ‐caprolactone) (PCL) was explored based on depolymerization and polymerization. The concept bases on the zinc‐catalyzed depolymerization via methanolysis to produce methyl 6‐hydroxyhexanoate, which is polymerized in a zinc‐catalyzed condensation reaction to generate new PCL and close the cycle. In more detail, with zinc(II) acetate as catalyst, PCL was depolymerized with turnover frequencies of up to 468 h −1 using microwave heating. On the other hand zinc(II) acetate was also able to catalyze the polymer formation using the monomer methyl 6‐hydroxyhexanoate. PCL was obtained in good yield and M n ∼1729 g/mol and M w ∼5823 g/mol were achieved.