Abstract
The ring-opening polymerization of L-lactide (L-LA) initiated by 1-dodecanol/tin(II) octoate was carried out in supercritical chlorodifluoromethane at 110 °C under a pressure of 200 bar. MALDI-TOF mass spectroscopy and 1H NMR studies suggested that polymerization proceeded via a traditional coordination-insertion mechanism involving a tin alkoxide bond and the cleavage of the acyl-oxygen bond of the monomer. The polymerization was controlled using the linear relation between ln([LA] 0/[LA]) on the polymerization time and the molecular weight on conversion. The relative polymerization rate constants increased with increasing tin(II) octoate and 1-dodecanol concentrations. Gel permeation chromatography analysis indicated that the molecular weight distribution was bimodal, at least for certain monomer conversion. The bimodal distribution may be a result of specific intermolecular interactions between chlorodifluoromethane and hydroxyl groups on 1-dodecanol or on dormant macromolecules. The mechanisms of the initiation and chain transfer steps of L-lactide polymerization in supercritical chlorodifluoromethane are proposed.
Original language | English |
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Pages (from-to) | 8923-8930 |
Number of pages | 8 |
Journal | Macromolecules |
Volume | 36 |
Issue number | 24 |
DOIs | |
Publication status | Published - 2003 Dec 2 |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry