Langmuir films of monohydroxamic acid on various ion-containing subphases

In order to get the most dense octadecanoyl monohydroxamate (C18N) monolayer developed at the air–water interface, the influences of various ions (Ca2+, Mg2+, Sr2+, Ba2+, and Fe3+ used at low concentrations) at various subphase pH values were studied by pressure–area (π–A) isotherms and Brewster angle microscopy (BAM). The change in the mean molecular area as a function of time at constant surface pressure was monitored to examine the monolayer stability under various experimental conditions. Both the density and the stability of the C18N Langmuir films are influenced by the presence of metal ions in the subphases. The change which depends on the type of ions added to the subphase as well as on the subphase pH value could be explained by the complex forming ability of cations with the C18N in the monolayer characteristics. Due to the high stability of C18N monolayers developed on ion-containing subphases, high-quality LB films onto solid substrates could be fabricated.