Well-defined amphiphilic block copolymers polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) and polystyrene-b-polyethylene oxide (PS-b-PEO) with controlled block length were synthesized using atomic-transfer radical polymerization (ATRP). The films fabricated by drop coating the block copolymer solution on mica show the marked microphase separated morphologies, which strongly depend on the block length ratio. The furrow maps of these films predict that they can be used as templates to prepare inorganic nanoparticles. (C) 2003 Elsevier B.V. All rights reserved.