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 journalArticlepeer-review

    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

    ASJC Scopus subject areas

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

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