The effect of different alcohols and other polar organic additives on the cloud point of Triton X-100 in water

The effect of 21 polar organic liquids additives (including 12 alcohols, two acids, two esters, two ketones, one ether, one formamide and one dioxan) on the cloud point of Triton X-100 (TX100) in aqueous solutions has been investigated. The results show that the addition of the polar organic liquid additives which are infinitely miscible with water increase the cloud point of the TX100, whereas the addition of the polar organic liquid additives which are partially soluble in water decreases the cloud point of TX100. In the former case, the addition of the polar organic liquids may modify the structure of the solvent water, leading to the formation of a less polar medium. This factor, in addition to the adsorption of the additive at the interface micelle-water originates a restriction of micellization and an increase in the cloud point. When the polar organic liquid is partially soluble in water, the molecules of additive may be solubilized in the micelles and adsorbed at the interface micelle-water. These facts could justify a micellar growth and a depression in the cloud point. For additives belonging to a particular homologous series the effect on the cloud point is correlated to the length of the hydrophobic alkyl chain. In general, a longer chain entails lower additive concentration for obtaining phase separation at a certain temperature. (C) 1999 Elsevier Science B.V. All rights reserved.