Ring-Opening Polymerization of ϵ-Caprolactone by Benzoic Acid in the Presence of Benzyl Alcohol as Initiator

Graphical Benzoic acid has been proved to be an efficient catalyst for the ring-opening polymerization of ϵ-caprolactone under mild conditions. A monomer-activated ring-opening polymerization mechanism mediated by benzoic acid was proposed. It is expected to realize the one-step preparing of poly (ϵ-caprolactone) through the direct aerobic oxidation of cyclohexanone. The development of a feasible industrial method for poly(ϵ-caprolactone) (PCL) preparation is great of significant and challenging. The bulk ring-opening polymerization of ϵ-caprolactone (ϵ-CL) using various organic acid catalysts and benzyl alcohol (BnOH) as the initiator was developed. Benzoic acid (BA) has been proved to be an efficient catalyst for the ROP of ϵ-CL under mild conditions. The conversion of ϵ-CL to PCL was 84.7 % under the optimized reaction conditions, with number-average molecular weight ( M n ) and dispersity (PDI) of 7700 g/mol and 1.25, respectively. Moreover, a monomer-activated ring-opening polymerization mechanism mediated by benzoic acid was proposed. Overall, this work is expected to provide a feasible industrial method for the preparation of PCL using benzoic acid as organocatalyst.