期刊
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
卷 42, 期 5, 页码 1132-1142出版社
WILEY
DOI: 10.1002/pola.11072
关键词
block copolymers; polyesters; polyethers
Ethylene oxide (EO) has been block-polymerized with both epsilon-caprolactone (epsilon-CL) and gamma-methyl-epsilon-caprolactone (MCL) through the combination of the anionic polymerization of EO and the ring-opening polymerization (ROP) of epsilon-CL and MCL. omega-Hydroxyl poly(ethylene oxide) has been reacted with triethylaluminum (OH/Al = 1) and converted into a macroinitiator for ROP of epsilon-CL and MCL. In toluene at room temperature, this polymerization leads to a bimodal molecular weight distribution as a result of monomer insertion in only some of the aluminum alkoxide bonds. However, in a more polar solvent (methylene chloride) added with 1 equiv of a Lewis base (pyridine), the expected diblock is formed selectively, and this indicates that aggregation of the active species in toluene is responsible for a macroinitiator efficiency of less than 1. A series of amphiphilic diblock copolymers with poly(epsilon-caprolactone) (semicrystalline) and poly(gamma-methyl-epsilon-caprolactone) (amorphous) as the hydrophobic blocks have been prepared and characterized with size exclusion chromatography, H-1 NMR, IR, and wide-angle X-ray scattering. (C) 2004 Wiley Periodicals, Inc.
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