A series of new mesomorphic block copolymers composed of different macroinitiators, including poly(ethylene oxide), polystyrene, and poly(ethylene oxide)-b-polystyrene, and polymethacrylate with a pendent cyanoterphenyl group were synthesized through atom transfer radical polymerization. The number-average molecular weights of the three diblock copolymers, determined by gel permeation chromatography, were 10,254, 9,772, and 15,632 g mol(-1), and their polydispersity indices were 1.17, 1.28, and 1.34. The mesomorphic and optical properties of all the block copolymers were investigated, and they possessed a smectic A phase with mesophasic ranges wider than 100 degrees C. Moreover, X-ray diffraction patterns provided evidence of the smectic A phase and the corresponding interdigitated packing of all the polymers. (c) 2006 Wiley Periodicals, Inc.