| 학회 |
한국고분자학회 |
| 학술대회 |
2004년 봄 (04/09 ~ 04/10, 고려대학교) |
| 권호 |
29권 1호, p.226 |
| 발표분야 |
기능성 고분자 |
| 제목 |
Effects of Pressure and Temperature on the Kinetics of L-Lactide Polymerization in Supercritical Chlorodifluoromethane |
| 초록 |
The ring-opening polymerization of L-lactide initiated by 1-dodecanol/stannous 2-ethylhexanoate (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 ℃. Increasing the pressure resulted in an accelerated polymerization rate. The activation volume for [DoOH]0/[Sn]]0 = 0 was determined to be −50 cm3/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-LA 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. |
| 저자 |
백지원1, 박현덕2, 이항수2, 박수영1, 이윤우1, 김수현2, 김영하2
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| 소속 |
1서울대, 2한국과학기술(연) |
| 키워드 |
pressure; temperature; kinetics; L-Lactide polymerization; supercritical; chlorodifluoromethane
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| E-Mail |
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