Well-defined poly(dimethylsiloxane-b-styrene) diblock copolymers were prepared by reversible addition fragmentation chain-transfer (RAFT) polymerization. Monohydroxyl-terminated polydimethylsiloxane was modified to form a functional polydimethylsiloxane/macro-RAFT agent, which was reacted with styrene to form the diblock copolymers. The chemical compositions and structures of the copolymers were characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography. The surface properties and morphology of the copolymers were investigated with static water contact-angle measurements, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, which showed a low surface energy and microphase separation surfaces that were composed of hydrophobic domains from polydimethylsiloxane segments. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 3283-3290, 2010