Dispersion polymerization of L-lactide in supercritical carbon dioxide
JOURNAL OF POLYMER RESEARCH, cilt.18, sa.5, ss.975-982, 2011 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 18 Sayı: 5
- Basım Tarihi: 2011
- Doi Numarası: 10.1007/s10965-010-9497-y
- Dergi Adı: JOURNAL OF POLYMER RESEARCH
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.975-982
- Anahtar Kelimeler: Poly(L-lactide), Ring-opening polymerization, Supercritical carbon dioxide, Triblock (A-B-A) stabilizers, epsilon-Caprolactone, Poly(ethylene glycol), RING-OPENING POLYMERIZATION, TRANSFER RADICAL POLYMERIZATION, EPSILON-CAPROLACTONE, PRECIPITATION POLYMERIZATION, BLOCK-COPOLYMERS, VINYL MONOMERS, CO2, METHACRYLATE), MICROSPHERES, STABILIZERS
- Atatürk Üniversitesi Adresli: Hayır
Özet
Triblock (A-B-A) oligomers of epsilon-caprolactone (epsilon-CL) (A) and poly(ethylene glycol) with an average molecular weight of 400 (PEG400) (B) were synthesized with three different molecular weight in the range of 2-6 kDa by changing the ratio of PEG400/epsilon-CL. These oligomers were then used in dispersion polymerization of L-lactide in supercritical carbon dioxide (scCO(2)) as stabilizers. 5% stabilizer in the polymerization recipe allowed synthesis of poly(L-lactide) (PLLA) in scCO(2) in the powder form with a weight average molecular weight of around 60 kDa with polymerization yields around 80%. Interestingly, there was almost no effect of stabilizer molecular weight on polymerization. L-lactide polymerization in scCO(2) without any stabilizer was also possible but both the PLLA molecular weight and polymerization yield were lower, and the product was as aggregates instead of powders. A stabilizer concentration of 5% in the polymerization recipe was found adequate. Further increases in the stabilizer load resulted lower molecular weights and lower yields.