Influence of Hydrotropes and Glycols on the Clouding Behavior of Surfactants (TritonX 100 and Brij 56) and Polymers (Polyvinylmethyl Ether and Triblock Co-Polymer, Pluronic 85)

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Nonionic surfactants and water-soluble polymers undergo phase transition and clouding at elevated temperature. The process can be influenced by the presence of additives. In this work, we have studied the clouding of the surfactants, TritonX 100 and Brij 56 as well as the polymers, polyvinylmethylether and a triblock co-polymer, Pluronic 85 in the presence of a number of hydrotropes, glycols and polyethylene oxides. The clouding temperatures with the additive concentration have been determined and the energetics of the process has been estimated. It has been found that the enthalpic behavior of TritonX 100 was different from that of polyvinylmethylether and Pluronic 85. The enthalpy and entropy have nicely compensated each other. The clouding of Brij 56 and TX 100 have a direct dependence on the number of ethylene groups in the glycols and the molar mass of the polyethylene oxides. The hydrotropes, on the whole, have decreased the cloud point of TX 100, polyvinylmethylether and Pluronic 85. Sodium cholate and sodium salicylate have increased the cloud point. But a correlation of the cloud points with the chemical nature of the hydrotropes is difficult to ascertain.
2003-10-01