Ring-opening polymerization of l-lactide in supercritical carbon dioxide using PDMS based stabilizers

• Published in: European polymer journal Vol. 43; no. 1; pp. 119 - 126
• Main Authors: Ganapathy, Hullathy Subban, Hwang, Ha Soo, Jeong, Yeon Tae, Lee, Won-Ki, Lim, Kwon Taek
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2007; Elsevier
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; PDMS based stabilizers; Physicochemistry of polymers; Poly( l-lactic acid); Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring-opening polymerization; Supercritical carbon dioxide; Suspension polymerization; Poly( l-lactic acid); Ring-opening polymerization; Supercritical carbon dioxide; Suspension polymerization; PDMS based stabilizers; Ring opening polymerization; Poly(L-lactic acid); Optically active polymer; Carbon dioxide; Polymerization under pressure; Experimental study; Structure processing relationship; Monodispersed polymer; Lactic acid polymer; Stabilizer agent; Morphology; Supercritical solvent; Microparticle; Comparative study; Amphiphilic polymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2006.10.009

Ring-opening suspension polymerization of
l-lactide in supercritical CO
2 (scCO
2) was investigated in the presence of different stabilizer architectures based on poly(dimethyl siloxanes) (PDMS). Two amphiphilic AB type block copolymers, a graft copolymer, and an ester-capped PDMS were selected to find their efficacy as stabilizers for the synthesis of poly(
l-lactide) (PLLA) in scCO
2. The stabilizer’s efficiency was analyzed in terms of the molecular weight, yield, and particle morphology of PLLA. The block copolymers, poly(dimethylsiloxane)-
b-poly(acrylic acid) (PDMS-
b-PAA) and poly(dimethylsiloxane)-
b-poly(methacrylic acid) (PDMS-
b-PMA) were found to be effective, leading to the formation of fine, discrete PLLA microparticles. On the other hand, the graft copolymer, poly(dimethylsiloxane-
g-pyrrolidonecarboxylic acid) (PDMS-
g-PCA) and acetylated PDMS (PDMS-OAc) failed to give an enough stabilization to the PLLA due to their short polymer-philic chains, resulting in hard agglomerates.