Regioregular poly(3-hexylthiophene)-b-poly(1H, 1H-dihydro perfluorooctyl methacrylate) (P3HT-b-PFOMA) diblock copolymers were synthesized by atom transfer radical polymerization of fluorooctyl methacrylate using bromoester terminated poly(3-hexylthiophene) macroinitiators in order to investigate their morphological properties. The P3HT macroinitiator was previously prepared by chemical modification of hydroxy terminated P3HT. The block copolymers were well characterized by (1)H NMR spectroscopy and gel permeation chromatography. Transmission electron microscopy was used to investigate the nanostructured morphology of the diblock copolymers. The block copolymers are able to undergo microphase separation and self-assemble into well-defined and organized nanofibrillar-like micellar morphology. The development of the morphology of P3HT-b-PFOMA block copolymers was investigated after annealing in solvent vapor and also in supercritical CO(2). (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4680-4686, 2011