Conventional expandable polystyrene (EPS) was chemically modified by preparing copolymers containing 0.1%, 0.2%, and 0.5% siloxane-based macroinitiator. This was used to enhance the surface and thermal properties of EPS particles. Copolymeric expandable polystyrene samples were characterized with various techniques including H-1-NMR, gel permeation chromatography, differential scanning calorimetry, scanning electron microscopy, and contact angle measurement. (c) 2006 Wiley Periodicals, Inc.