Controlled/living ring-opening polymerization of ε-caprolactone with salicylic acid as the organocatalyst

Ring-opening polymerization (ROP) of ε -caprolactone (CL) using salicylic acid (SAA) as the organocatalyst and benzyl alcohol as the initiator in bulk at 80 °C successfully proceeded to give a narrowly distributed poly( ε -caprolactone) (PCL). In addition, 2-hydroxyethyl methacrylate, propargyl alcohol, 6-azido-1-hexanol, and methoxy poly(ethylene glycol) were also used as functional initiators. The 1 H NMR, SEC, and MALDI-TOF MS measurements of the PCL clearly indicate the presence of the initiator residue at the chain end, implying that the SAA-catalyzed ROP of CL was through the activated monomer mechanism. The kinetic experiments confirmed the controlled/living nature of the SAA-catalyzed ROP of CL. Furthermore, the block copolymerization of CL and δ -valerolactone successfully proceeded to give poly( ε -caprolactone)- block -poly( δ -valerolactone). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 1185–1192