Amphiphilic polylactides (PLAs) with well-defined architectures were synthesized by ring-opening polymerization of AB monomers (glycolides) substituted with both a long chain alkyl group and a triethylene glycol segment terminated in either a methyl or benzyl group. The resulting amphiphilic PLAs had number average molecular weights >100,000 g/mol. DSC analysis revealed a first-order phase transition at similar to 20 degrees C, reflecting the crystalline nature of the linear alkyl side chains. Polymeric micelles were prepared by the solvent displacement method in water. Dynamic light scattering measurements support formation of a mixture of 20-nm-diameter unimolecular micelles and 60-nm particles comprised of an estimated 25 polymer molecules. UV-vis characterization of micelles formed from acetone-water solutions containing azobenzene confirmed encapsulation of the hydrophobic dye, suggesting their potential as new amphiphilic PLAs as drug delivery vehicles. (c) 2007 Wiley Periodicals, Inc.