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|Title:||Clouding and aggregation behaviour of ethylene oxide/propylene oxide/ethylene oxide block copolymers in aqueous media in the presence of sodium dodecyl sulphate|
|Abstract:||The interaction of ethylene oxide-propylene oxide-ethylene oxide block copolymers (F-68, L-64 and P-85) with sodium dodecyl sulphate (SDS) in aqueous medium has been studied using various physical properties viz., cloud point, surface tension, dye solubilization, conductivity and viscosity. Dynamic light scattering (DLS) has been used to determine the size of aggregates of copolymer/SDS micelles. The cloud points (CP) of copolymer solutions increase in the presence of SDS; the CP increase is dependent on the hydrophobicity of the copolymer and its concentration. Surface tension/dye solubilization data support the aggregation of SDS taking place at concentration much below its critical micelle concentration (cmc); the copolymer-SDS mixed systems have enhanced surface activity and solubilizing power. Viscosity data reveal that the copolymer-SDS complex (or mixed micelles) possesses polyelectrolyte-like nature. The strength of. the SDS-copolymer interaction seems in the order P-85 > L-64 > F-68. DLS data indicate that the addition of SDS to L-64 solution in water gradually decreases the hydrodynamic radius of the micelles; however, no change in micelle size of L-64 is detected in the presence of 1.0M NaCI on addition of SDS. Small quantities of copolymer added to SDS solutions in water in the presence of calcium chloride reduce the turbidity and thus improve the hardness tolerance.|
|Appears in Collections:||IJC-A Vol.34A(12) [December 1995]|
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