Poly(siloxane-fluoroacrylate)-grafted silica hybrid nanoparticles were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). The silica nanoparticles with alpha-bromo-ester initiator group for copper-mediated ATRP were prepared by the self-assembled monolayers of (3-aminopropyl)triethoxysilane and 2-bromoisobutyrate bromide. Well-defined diblock copolymer brushes consisting of poly(methacryloxypropyltrimethoxysilane) and poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) blocks were obtained by using initial homopolymer brushes as the macroinitiators for the SI-ATRP of the second monomer. Chemical compositions and structures of the nanoparticles were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Surface properties and morphology of the nanoparticles were investigated with X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle measurement. It is revealed that the surfaces of the nanocomposites are rough at the microscale and nanoscale. The formation reason of the superhydrophobic surfaces was also discussed in this work. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5570-5580, 2010