Polymer Communication Polymeric Langmuir–Blodgett films containing imidazole-coordinated metal complexes H. Jeong a , B.-J. Lee b , W.J. Cho a , C.-S. Ha a, * a Department of Polymer Science and Engineering, Pusan National University, Pusan 609-735, South Korea b Department of Chemistry, Inje University, Kimhae 621-749, South Korea Received 1 September 1999; received in revised form 9 November 1999; accepted 17 November 1999 Abstract 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 + , Mg 2+ , and Fe 3+ ) 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-IR 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.  2000 Elsevier Science Ltd. All rights reserved. Keywords: Monolayer; LB film; Metal-ion 1. Introduction Molecularly thin films of polymer–metal complexes have attracted interest because of their potential application to sensors, catalytic systems, and molecular electronic devices [1]. The Langmuir–Blodgett (LB) technique can provide highly ordered molecular films, which in turn can produce multilayers of properly designed structures and thickness [2]. Recently, the incorporation of metal ions in LB films has been investigated in various fields of potential appli- cations [3–5]. However, not much effort has been made regarding the coordination properties of polymeric mono- layers spread on aqueous subphases containing metal ions [6–10]. We have however, focused on the functionalities of the imidazole group in the living system, particularly as ligands to metal ions [11–14], and attempted to fabricate imidazole- containing LB films in order to realize the imidazole–metal coordination at the monolayer system [15]. Octadecyl urocanate (OU) showed characteristic monolayer behavior at the air–water interface. The molecular surface area of the OU monolayer was expanded on acidic and basic subphases compared with that on pure water subphases. Meanwhile, the monolayers on subphases containing metal ions showed condensed phases due to imidazole–metal interactions. Additionally, the 2 + 2 photochemical cyclization between the OU molecules in the LB film was demon- strated. As other examples of using imidazole-containing amphiphiles for monolayer spreading, 2-heptadecylimida- zole [16] was used to fabricate a LB film for the photoin- duced proton transfer, and chiral derivatives of N-alkyl imidazole [17] were spread on metal ion-containing subphases and their two-dimensional aggregation morphol- ogy was investigated by fluorescence microscopy. The aims of the present work are to study the formation and structure of a coordination complex between the metal ion and the ligand monolayer in the LB films and to explore the possibility of obtaining ion sensors using the LB films. Particularly, we report in this paper, the synthesis of an amphiphilic polymeric imidazole, which can be spread to stable monolayers on water surface and the interaction of the polymer with metal ions at the air–water interface. The polymer was expected to fabricate stable LB films compared Polymer 41 (2000) 5525–5529 0032-3861/00/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S0032-3861(99)00831-9 * Corresponding author. Fax: +82-51-514-4331. E-mail address: csha@hyowon.pusan.ac.kr (C.-S. Ha).