Amphiphilic triblock copolymers, poly(ethyl cyanoacrylate)-b-poly(ethylene glycol)-b-poly(ethyl cyanoacrylate) (PECA-b-PEG-b-PECA), were synthesized via oxyanion-initiated polymerization with sodium alcoholate-terminated PEG as macroinitiator. PECA-b-PEG-b-PECA were characterized by gel permeation chromatography system, H-1 NMR and FTIR. The results indicate that the copolymerization is well controlled with narrow molecular weight distribution. The dexamethasone (DXM)-loaded PECA-b-PEG-b-PECA nanoparticles (NPs) were prepared by nanoprecipitation technique and then characterized by Laser Particle Size Analyzer, H-1 NMR and transmission electron microscopy. The drug-loaded PECA-b-PEG-b-PECA NPs are of spherical shape with average size of less than 100 nm. The drug-loaded amount (DLA) and encapsulation efficiency of DLNPs were investigated by HPLC. The results show that DXM can be effectively incorporated into PECA-b-PEG-b-PECA NPs, which provides an optional delivery system for DXM and other hydrophobic drugs. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7809-7815, 2008