Study of an Imidazole Derivative Mixed with Fatty Acid at Air-Water Interface and in Ultrathin Films

Abstract

Mixed monolayers have gained more and more interest in the field of monolayer research due to the vast properties of the multicomponent system than that of the pure one. This article reports the thinfilm forming behavior of an important imidazole derivative 2-(4-O-octadecyloxyphenyl)-4,5-diphenyl imidazole (1) mixed with a fatty acid (Stearic Acid, SA) at air-water interface and in thin films using Langmuir-Blodgett (LB) technique. The interfacial behavior as well as the morphology of films were studied through a series of characterization methods such as surface pressure – area (π-A) isotherm, Brewster angle microscopy (BAM), atomic force microscopy (AFM) measurements etc. π-A isotherms clearly ravels the strong interaction between the constituents molecules. Excess area and Gibb’s free energy analysis of the mixed monolayer confirms the repulsive interaction between the binary molecules in the mixed monolayer. BAM and AFM measurements shows the formation of various nanostructures mainly nanorods for pure 1 and uniform domains of nanoballs for mixed 1+SA molecules at air-water interface as well as in LB films.