Influence of PVP and PEO on Cloud Point of Poly (oxyethylene) 10 Oleyl Ether (Brij-97): A Thermodynamic Approach

Balkrishna B Patil, Gunvant H

Abstract

The cloud point (CP) temperature was investigated for aqueous solutions of poly(oxyethylene) 10-oleyl ether (Brij-97) and it’s mixture with polymer, poly vinyl pyrolidone (PVP) and poly ethylene oxide (PEO) at different concentrations. The cloud point of pure Brij-97 was found to be decreased with increasing concentration. At fixed concentration of surfactant, the CP of mixed system shows decreasing trends with increasing concentration of PVP and increases with increasing concentration of PEO. Considering the cloud point as threshold temperature of the solubility, the thermodynamic parameters of clouding process (ΔG0Cl, ΔH0Cl and ΔS0Cl) has been evaluated using “Phase Separation Model”. The phase separation results from micelle-micelle interaction. It was found that the overall clouding process was endothermic and ΔS0Cl>ΔH0Cl, indicating that the process of clouding was guided by both enthalpy and entropy.