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

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YILMAZ M., EĞRİ S., YILDIZ N., ÇALIMLI A., Piskin E.

POLYMER JOURNAL, cilt.43, sa.9, ss.785-791, 2011 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 43 Sayı: 9
  • Basım Tarihi: 2011
  • Doi Numarası: 10.1038/pj.2011.70
  • Dergi Adı: POLYMER JOURNAL
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.785-791
  • Hacettepe Üniversitesi Adresli: Evet

Özet

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