Kinetic and Mechanistic Studies of L-Lactide Polymerization in Supercritical Chlorodifluoromethane

Ji Won Pack, Soo Hyun Kim, Soo Young Park, Youn Woo Lee, Young Ha Kim

Research output: Contribution to journalArticle

27 Citations (Scopus)

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 languageEnglish
Pages (from-to)8923-8930
Number of pages8
JournalMacromolecules
Volume36
Issue number24
DOIs
Publication statusPublished - 2003 Dec 2
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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