Diblock copolymers, in which both blocks are composed of aliphatic polyesters, were synthesized from two different alkyne-functionalized delta-valerolactone monomers by ring opening polymerization and subsequent click cycloaddition. Trimethylsilyl protection of the alkyne functionality of one block was instrumental to the success of the synthesis. These novel aliphatic polyester diblock copolymers were characterized by H-1 and C-13 NMR spectroscopy, gel permeation chromatography (GPC), and infrared (M) spectroscopy. Sequential functionalization of the diblock copolymers with hydrophobic groups on one block, and hydrophilic groups on the other block, provides access to amphiphilic structures Micellar structures generated from these polyester amphiphiles were characterized by fluorescence spectroscopy and transition electron microscopy (TEM) (C) 2009 Wiley Periodicals, Inc J Polym Sci Part A Polym Chem 47. 7054-7065, 2009