Reaction kinetics of organo-clay hybrid films: In-situ IRRAS, FIM and AFM studies Original Research Article

In this paper we report the reaction kinetics of nanodimensional clay saponite and hectorite with an amphiphilic cation octadecyl rhodamine B (RhB) in hybrid Langmuir monolayer at the air–aqueous clay dispersion interface. The surface pressure–molecular area (π–A) isotherms were strongly influenced by the presence of clay and the lift-off area of the cationic amphiphile shifted to progressively larger area. In-situ fluorescence imaging microscopic (FIM) studies showed the formation of micro-order domains in the organo-clay hybrid monolayer films at the air–clay dispersion interface. In-situ infrared reflection–absorption spectroscopy (IRRAS) was used to demonstrate the reaction kinetics. The time taken to complete the reaction kinetics for RhB–hectorite hybrid films is larger than for RhB–saponite hybrid films. Atomic force microscopic images of hybrid Langmuir–Blodgett films gave compelling visual evidence of the incorporation of clay platelets into the hybrid films, whose density increased with the progress of reaction kinetics.