Effects of pressure and temperature on the kinetics 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

12 Citations (Scopus)

Abstract

The ring-opening polymerization of L-lactide initiated by 1-dodecanol/stannous 2-ethylhex-anoate (DoOH/Sn(Oct)2) was carried out in supercritical chlorodifluoromethane at pressures ranging from 180 to 360 bar and at temperatures ranging from 100 to 130°C. Increasing the pressure resulted in an accelerated polymerization rate. The activation volume for [DoOH]0/[Sn]0 = 0 was determined to be -50 cm 3/mol. The partial bond formation in the transition state contributed to the negative value of the activation volume and the pressure-induced acceleration in the rate of L-lactide polymerization, i.e., by producing a four-center transition state and a lower partial molar volume. A further stabilization of the transition state in terms of the activation volume of-61 cm3/mol by the use of DoOH ([DoOH]0/[Sn]0 = 1.0) can be explained by sterically crowded transition state. A computational study using semiempirical methods showed the transition state is subject to weak electrostriction effects. The observed activation energy (88.7 kJ/mol), which is higher than that in bulk, reflects a partial blocking of the active coordinate site by chlorodifluoromethane.

Original languageEnglish
Pages (from-to)3564-3568
Number of pages5
JournalMacromolecules
Volume37
Issue number10
DOIs
Publication statusPublished - 2004 May 18
Externally publishedYes

Fingerprint

Chemical activation
Polymerization
Kinetics
Dodecanol
Electrostriction
Ring opening polymerization
Density (specific gravity)
Temperature
Stabilization
Activation energy
dilactide
fluorocarbon 22
2-ethylhexanoic acid tin(II) salt

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Effects of pressure and temperature on the kinetics of L-lactide polymerization in supercritical chlorodifluoromethane. / Pack, Ji Won; Kim, Soo Hyun; Park, Soo Young; Lee, Youn Woo; Kim, Young Ha.

In: Macromolecules, Vol. 37, No. 10, 18.05.2004, p. 3564-3568.

Research output: Contribution to journalArticle

Pack, Ji Won ; Kim, Soo Hyun ; Park, Soo Young ; Lee, Youn Woo ; Kim, Young Ha. / Effects of pressure and temperature on the kinetics of L-lactide polymerization in supercritical chlorodifluoromethane. In: Macromolecules. 2004 ; Vol. 37, No. 10. pp. 3564-3568.
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