Poly(ionic liquid) surfaces with tunable wettability were successfully prepared on micro/nanoscale CuO/Cu composite substrates by a surface-initiated nitroxide-mediated radical polymerization technique. Various characterization techniques including X-ray photoelectron spectroscopy, cold field emission scanning electron microscopy, and static water contact angle measurement were used to characterize the surfaces for each surface modification step. Kinetic studies revealed that the polymer chain growth from the surface was a controlled/living polymerization process. The surface with tunable wettability, reversible switching between hydrophilicity and hydrophobicity can be easily achieved by sequential counteranion exchange. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013