The monodisperse poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAAm)) particles prepared by emulsifier-free emulsion polymerization with microwave irradiation were induced by capillary forces to self-assemble, and formed the two-dimensional films on the clean glassware wafer substrates. The morphologies of the two-dimensional films were characterized by scanning electron microscopy (SEM) and atom force microscopy (AFM). The results showed that monodisperse poly(St-co-NIPAAm) particles could form ordered two-dimensional films by capillary forces. With NIPAAm concentration increasing, there gradually appeared surface undulations or surface defective region on the two-dimensional films. (c) 2006 Wiley Periodicals, Inc.