Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB) on interactions of glycyl dipeptide in aqueous medium have been studied in varying concentrations (0.001, 0.005 and 0.010 mol kg 1) at different temperatures (293.15 K to 293.15 K). The conductivity method has been employed to determine critical micelle concentration, CMC i.e. point of aggregation and the results have been discussed in terms of glycylglycine CTAB/DTAB hydrophobic and electrostatic interactions in aqueous medium. The obtained CMC values reveal the fact that the micellization tendency of the surfactant increases in the presence of glycyl dipeptide. The CMC s of CTAB and DTAB have been found to decrease from 0.87 to 0.66 mmol kg 1 and 14.2 13.7 mmol kg 1 respectively as the [Glycyl dipeptide] increased from 0.001 to 0.010 mol kg 1. The temperature dependence of the CMC values has been established in terms of ion ion, ion polar and hydrophobic hydrophobic group interactions around the hydrophobic part of surfactants. Furthermore, the standard thermodynamic parameters of micellization have been evaluated and interpreted which enable to grasp fully the ion ion/ion hydro philic interactions existing in the present ternary (surfactant dipeptide water) system. In addition, the pyrene fluorescence technique has been used to study the change of micropolarity produced by the interactions of surfactants with glycyl dipeptide and the aggregation behaviour (CMC determination) of surfactants.