LANGMUIR-BLODGETT-FILMS OF A POLYMERIZABLE N,N'-DISUBSTITUTED DITHIOOXAMIDE COORDINATION COMPOUND

The monolayer properties of the amphiphile ,12-pentacosadiynyloxycarbo nylmethyl)dithiooxamide at the air-water interface were studied by mea suring surface pressure-area isotherms. The amphiphile itself does not form stable monolayers on an aqueous subphase but when Cu(II) ions ar e added to the subphase a coordination polymer is formed, which forms stable monolayers at the air-water interface. The monolayer stability is strongly influenced by the counterion, pH and temperature of the su bphase. Electron microscopy shows that at a low surface pressure (abou t 2 mN m(-1)) a monolayer of loosely packed islands is formed. When th e surface pressure has increased a more homogeneous monolayer is forme d with small holes which disappear when the monolayer is stabilised at a constant surface pressure for a few hours. The monolayers of the co ordination polymer can be transferred onto solid substrates by a Y-typ e transfer. The presence of Cu(II) ions is confirmed by XPS measuremen ts and UV/Vis spectroscopy shows a strong absorption at 370 nm, indica ting that a strongly conjugated coordination polymer is formed at the air-water interface. SAXR measurements reveal that the LB films have a rather irregular layer structure and upon exposure to UV light, the d iacetylene groups are only partly converted to polydiacetylene; moreov er, the coordination polymer is partly destroyed. (C) 1998 Elsevier Sc ience S.A. All rights reserved.