Ring opening polymerization of 1 4 dioxan 2 one in bulk was initiated by three titanium alkoxides titanium dichloro diisopropoxide (TiCl2(OiPr)(2)) titanium chlorotriisopropoxide (TiCl2(OiPr)(3)) and titanium tetraisopropoxide (T-i(OiPr)(4)) The results indicate that the polymerization rate increased with num ber of OiPr groups in the initiator High conversion of monomer (90%) and high molecular weight (11 9 x 10(4) g/mol) of resulting polymer can be achieved in only 5 min at 60 degrees C with Ti(OiPr)(4) as an initiator Analysis on nuclear magnetic resonance (NMR) spectra suggests the initiating sites for TiCl2(OiPr)(2) TiCl2(OiPr)(3) and Ti(OiPr)(4) to be 1 9 2 6 and 3 8 respectively Coordination insertion mechanism for the polymerization via cleavage of the acyl-oxygen bonds of the monomer was proved by NMR inves tigation Kinetic studies indicate that polymerization initiated by Ti(OiPr)(4) followed a first order kinetics with an apparent activa tion energy of 337 kJ/mol It is noteworthy that this value is significantly lower than earlier reported values with other cata lysts namely La(OiPr)(3) (50 5 kJ/mol) and Sn(Oct)(2) (71 8 kJ/mol) which makes it an attractive catalyst for reactive extrusion poly merization (C) 2010 Wiley Periodicals Inc J Polym Sci Part A Polym Chem 48 5885-5890 2010