Reaction-kinetics of organo-clay hybrid films: in-situ IRRAS and AFM studies

TL;DR

This study investigates the reaction kinetics of clay mineral hybrids with an amphiphilic dye at the air-water interface using IRRAS and AFM, revealing differences in reaction times and structural incorporation.

Contribution

It provides in-situ IRRAS and AFM analysis of the reaction kinetics and structural integration of clay minerals with an amphiphilic dye in hybrid films.

Findings

Reaction kinetics vary between saponite and hectorite hybrids.

IRRAS confirms the progression of the chemical reaction.

AFM images show increased clay incorporation over time.

Abstract

In this paper we have reported the reaction kinetics of nano dimensional clay saponite and hectorite with an amphiphilic cation octadecyl rhodamine B (RhB) in hybrid Langmuir monolayer at the air-water interface. The surface pressure-molecular area (pi-A) isotherms were strongly influenced by the presence of clay with the lift-off area of the cationic amphiphile shifted to progressively larger area. In-situ infrared reflection absorption spectroscopy (IRRAS) was used to demonstrate the reaction kinetics. Time taken to complete the reaction kinetics for RhB-hectorite hybrid films is larger than RhB-saponite hybrid films. Atomic force microscopic images of hybrid Langmuir-Blodgett films give compelling visual evidence of the incorporation of clay platelets into the hybrid films and density of which increases with the progress of reaction kinetics.