Rapid ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by titanium alkoxides |
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| Authors: | Jian‐Bing Zeng Madhusudhan Srinivansan Yi‐Dong Li Ramani Narayan Yu‐Zhong Wang |
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| Institution: | 1. State Key Laboratory of Polymer Materials Engineering, Center for Degradable and Flame‐Retardant Polymeric Materials, College of Chemistry, National Engineering Laboratory of Eco‐Friendly Polymeric Materials (Sichuan), Sichuan University, Chengdu 610064, China;2. Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824 |
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| Abstract: | Ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk was initiated by three titanium alkoxides, titanium dichlorodiisopropoxide (TiCl2(OiPr)2), titanium chlorotriisopropoxide (TiCl(OiPr)3), and titanium tetraisopropoxide (Ti(OiPr)4). The results indicate that the polymerization rate increased with number of OiPr groups in the initiator. High conversion of monomer (90%) and high molecular weight (11.9 × 104 g/mol) of resulting polymer can be achieved in only 5 min at 60 °C with Ti(OiPr)4 as an initiator. Analysis on nuclear magnetic resonance (NMR) spectra suggests the initiating sites for TiCl2(OiPr)2, TiCl(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 investigation. Kinetic studies indicate that polymerization initiated by Ti(OiPr)4 followed a first‐order kinetics, with an apparent activation energy of 33.7 kJ/mol. It is noteworthy that this value is significantly lower than earlier reported values with other catalysts, 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 polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 |
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| Keywords: | biocompatibility biodegradable poly(1 4‐dioxan‐2‐one) ring‐opening polymerization titanium alkoxide |
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