The binding property and complex structure of an imidazole-containing polymer with metal ions were investigated at the air-water interface and in the LB films. An amphiphilic polymer, poly(N-(2-(4-imidazolyl)ethyl)maleimide-alt-1-octadecene) (IM-O), was synthesized by the reaction of poly(maleic anhydride-alt-1-octadecene) with histamine. A dimethylsulfoxide/chloroform solution of IM-O was spread on pure water or aqueous metal ion (K+, Mg2+, and Fe3+) subphases. The monolayers were not collapsed until the surface pressure of 40 to 50 mN/m. The surface pressure-area isotherms of IM-O monolayers did not show noticeable difference according to the kinds of subphase. The images of Brewster angle microscopy revealed straight lines after monolayer collapse. The ferric ion-complexed monolayer was transferred onto solid substrates as Y-type. The molecular structure and orientation in the LB films were investigated by means of FT-LR and surface-enhanced Raman spectroscopy. The surface morphology of the LB film was obtained by atomic force microscopy. The quantitative analysis of metal ion concentration incorporated into the LB films was accomplished by means of XPS measurements. The mechanical stability of the LB films was indirectly estimated by SEM observation of the surface morphology of the porous FP-010 membrane covered with the LB films. (C) 2000 Elsevier Science Ltd. All rights reserved.