Macromolecular Research

, Volume 14, Issue 5, pp 510–516 | Cite as

Synthesis of lactide from oligomeric PLA: Effects of temperature, pressure, and catalyst

  • Dong Keun Yoo
  • Dukjoon Kim
  • Doo Sung Lee


Lactide was produced from oligomeric PLA by back-biting reaction of the OH end groups. For optimization of the reaction conditions, the effects of temperature, pressure, PLA molecular weight, and catalyst type on the lactide synthesis were examined. The fraction of D,L-lactide decreased with increasing temperature. Among the various Sn-based catalysts, the D,L-lactide fraction was maximized when SnO was used. A higher yield with lower racemization was observed at lower pressure. The conversion of PLA was maximized at an oligomeric PLA molecular weight of ca. 1380. The yield of lactide increased but the fraction of D,L-lactide decreased with increasing molecular weight. The highest conversion with the lowest racemization degree was obtained at a catalyst concentration of 0.1 wt%. The lactide was more sensitive to racemization because of the entropic effect.


poly(lactic acid) D,L-lactide meso-lactide catalysts depolymerization racemization deprotonation 


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Copyright information

© The Polymer Society of Korea and Springer 2006

Authors and Affiliations

  1. 1.Department of Chemical Engineering, Polymer Technology InstituteSungkyunkwan University SuwonGyeonggiKorea
  2. 2.Department of Polymer Engineering, Polymer Technology InstituteSungkyunkwan UniversitySuwon, GyeonggiKorea

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