Three Component Complex Langmuir - Blodgett Films of Water Soluble Eosin Y With Dodecyl Trimethyl Ammonium Bromide and Stearic Acid

Abstract

In the present communication we report the formation of nano dimensional complex films of eosin Y (EY), stearic acid (SA) and dodecyl trimethyl ammonium bromide (DTAB) using Langmuir - Blodgett (LB) technique. By spreading SA onto the DTAB - EY mixed aqueous sub phase a complex monolayer of SA-DTAB-EY was formed. The adsorption kinetics in the complex monolayer was investigated by recording increase in surface pressure with time (S-t) graph at air - water interface. Initially the (S-t) graph shows steep rise and becomes flat at the end of the adsorption kinetics. More than 300 minutes were required to complete the adsorption process. In situ Brewster Angle Microscopy investigation gives compelling visual evidence of complex Langmuir monolayer formation at air-water interface. After transfer onto solid substrate the films were characterized by UV-Vis absorption and Atomic Force Microscopy (AFM). In the complex LB films the EY absorption bands were shifted and broadened with respect to pure EY solution and microcrystal spectrum due to the formation of nano dimensional aggregates. This was also supported by AFM investigations of the complex LB films.