Ring-opening copolymerization of L-lactide and epsilon-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

Creative Commons License


POLYMER JOURNAL, vol.43, no.9, pp.785-791, 2011 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 9
  • Publication Date: 2011
  • Doi Number: 10.1038/pj.2011.70
  • Journal Name: POLYMER JOURNAL
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.785-791
  • Hacettepe University Affiliated: Yes


In this study, the use of triblock (A-B-A) oligomers of epsilon-caprolactone (epsilon-CL) (A) and PEG400 (B) as stabilizers (SB) for the copolymerization of L-lactide (LLA) and epsilon-CL in supercritical carbon dioxide (scCO(2)) was investigated. To determine the effect of CO2-philic and polymer-philic segments on copolymerization, oligomers with three different average molecular weights (M-w=2000-6000 Da) were synthesized by changing the PEG400/epsilon-CL ratio. Copolymerizations were confirmed by H-1-nuclear magnetic resonance (NMR), C-13-NMR and differential scanning calorimeter data. It was possible to copolymerize LLA and e-CL in scCO(2) without any SB; however, the polymerization yields and average molecular weights were low, and significant aggregate formations were detected. Recipes featuring only 5% SB were successfully applied to reach high polymerization yields of similar to 85% and polymers with average molecular weights greater than 20 kDa. When the polymer-philic segment of the SB increased, both the yield and molecular weight of the copolymer also increased significantly, resulting in white powdery products. Polymer Journal (2011) 43, 785-791; doi: 10.1038/pj.2011.70; published online 27 July 2011