Synthesis and characterization of Ti-/Zr-diphenylpropanedione complexes and their application in the ring opening polymerization of Ɛ-caprolactone

The purpose has been to achieve a controlled ring-opening polymerization of ɛ-caprolactone, resulting in polymers with desirable properties such as high molecular weight, low polydispersity index, and highly regio-/stereo regular forms. Therefore, it is important to synthesize single site or reduced number of active site metal alkoxide compounds as catalysts. Ti(IV)/Zr(IV) diphenylpropanedione complexes were synthesized by reactions of titanium or zirconium alkoxides with diphenylpropanedione (dion) ligand. The obtained complexes were characterized by nuclear magnetic resonance (1H-, 13C-NMR), high resolution mass (HRMS), Fourier transform infrared (FTIR) spectroscopies and elemental analysis. These compounds were tested as catalysts for the ring opening polymerization of Ɛ-caprolactone. The structure of poly-caprolactone (PCL) was analyzed by some spectroscopic techniques (NMR, FTIR) and gel permeation chromatography (GPC). In this work, all Ti-/Zr-complexes were effective over polymerization of Ɛ-caprolactone in solventless environment. Consequently, Ɛ-caprolactone polymers were obtained different average molecular weights between 7000-34000 Da with the PDI values of 1.14-1.60