This study compares the stability of various polymeric thin films supported on SiOx/Si substrate. Dewetting behaviors of polystyrenes (PS), polychloromethylstyrenes, and random poly(styrene-co-chloromethylstyrene)s are investigated by utilizing atomic force microscopy. A systematic addition of the chloromethylstyrene (CIMS) unit into PS chain causes the increase of segment polarity, affecting interfacial and interchain interactions in thin films. It is found that stability of the polymeric films depends on two major parameters, ratio of the CIMS unit and film thickness. For similar to 5 nm thick film, the addition of only 5 mol% CIMS unit causes a drastic increase of its stability, attributed to the enhanced interfacial interactions between CIMS group and SiOx layer. Further increasing the CIMS mole ratio to 20, 45, and 100% is accompanied by a systematic increase of the film stability. Thicker films (thicknesses similar to 22 and similar to 45 nm) of the copolymer with 5 mol% CIMS unit exhibit rather different behavior. They are found to be less stable compared to the PS films. However, the films of copolymers with CIMS unit of 20, 45, and 100% are still much more stable than the PS films. These dewetting behaviors of the copolymers are correlated to the interfacial interactions, interchain interactions and segmental segregation in thin films. (c) 2007 Elsevier Inc. All rights reserved.