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Ring‐Opening Polymerization of L ‐Lactide and Preparation of Its Microsphere in Supercritical Fluids
Author(s) -
Pack Ji Won,
Kim Soo Hyun,
Park Soo Young,
Lee YounWoo,
Kim Young Ha
Publication year - 2004
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200300089
Subject(s) - microsphere , lactide , supercritical fluid , polymerization , ring opening polymerization , polymer chemistry , chemistry , polymer science , chemical engineering , polymer , organic chemistry , engineering
Summary: The ring‐opening polymerization of L ‐lactide initiated by stannous octoate was carried out in supercritical chlorodifluoromethane (scR22) at various reaction conditions (time and temperature) and reactant concentrations (initiator, monomer, and solvent). The monomer conversion increased to ca. 70% on increasing the reaction time to 1 h. The molecular weight of the poly( L ‐lactide) (PLLA) product also increased to ca. 160 000 g · mol −1 over the same period. Increasing reaction temperature from 90 to 130 °C resulted in increased monomer conversion and PLLA molecular weight. A series of polymerizations conducted at various 1‐dodecanol and stannous octoate concentrations suggested that stannous octoate does not act as an initiator by itself, and that the tin‐alkoxide formed from 1‐dodecanol and stannous octoate serves as the initiating species in scR22. While enhancements of the monomer conversion and PLLA molecular weight were observed with increasing monomer concentration, the chlorodifluoromethane concentration had the opposite on both. After the polymerization, PLLA microspheres were prepared in situ by using a continuous supercritical antisolvent process without residual organic solvent and monomer to yield highly purified microspheres for environmental and biomedical applications.Relation between monomer conversion (○) and poly( L ‐lactide) molecular weight (•).