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 (H 2 L) was prepared and characterized by elemental analysis, thermogravimetric analysis (TGA), and FT-IR, UV–vis and 1 H NMR spectroscopy. The complex [Zn(L)(H 2 O)]·H 2 O was active in the ring opening polymerization (ROP) of e-caprolactone under solvent-free conditions, producing polycaprolactone (PCL) with a molecular weight up to 17,700 g mol −1 and a narrow molecular weight distribution. 1 H 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.