Coumarin salen-based zinc complex for solvent-free ring opening polymerization of ε-caprolactone

Abstract

A new zinc complex based on a tetradentate N,N,O,O-type coumarin salen ligand (H2L) was prepared and characterized by elemental analysis, thermogravimetric analysis (TGA), and FT-IR, UV–vis and 1H NMR spectroscopy. The complex [Zn(L)(H2O)]·H2O was active in the ring opening polymerization (ROP) of ε-caprolactone under solvent-free conditions, producing polycaprolactone (PCL) with a molecular weight up to 17,700gmol−1 and a narrow molecular weight distribution. 1H NMR analysis showed that the PCL obtained was mainly linear, having hydroxymethylene groups in the chain ends. Differential scanning calorimetry (DSC) showed that the polymer had high crystallinity (61%) and that TGA had a decomposition temperature above 300°C.