End silane functionalized polystyrene and polymethylmethacrylate were prepared through radical chain-transfer reaction and characterized with gel-permeation chromatography. The chain-transfer constants of mercaptopropyltrimethoxysilane for the polymerization of styrene and methylmethacrylate were determined to be 8.48 and 0.67, respectively, from the slopes of 1/DPn versus [S]/[M] lines. The ultrathin films of the end silane-terminated polymers were prepared by self-assembly onto hydroxylated silicon wafers. The water contact angle on the resulting ultrathin films and the film thickness were measured. The morphology and chemical features of the films were observed and investigated by means of atomic force microscopy and X-ray photoelectron spectroscopy. Results indicated that the chain-transfer agent played a key role in making it possible for the silane-terminated polystyrene and polymethylmethacrylate to be self-assembled on Si(111), whereas the thickness and surface quality of the ultrathin films were dependent on the molecular weights of the polymers. (C) 2004 Wiley Periodicals, Inc.