Effect of non-electrolyte additives on micellization and clouding behavior of silicone surfactant in aqueous solutions

In the presence of polar non-electrolytes, the micellization of silicone surfactant is disfavorable and micelles become smaller in size. While in the case of non-polar organic additives micellization is favorable and decreases the cloud point. [Display omitted] ► Cloud point and CMC values can be tuned by adding different non-electrolytes. ► Non-electrolytes like short chain alcohols increase CMC as well as clouding behavior. ► As alkyl chain length increases the solubility of alcohols decreases in water which leads to suppress the cloud point of aqueous solution of silicone surfactant. ► Similar effect was observed in the case of diethylene glycol, triethylene glycol and PEG having different molecular weights. ► Almost all short chain amides increase the clouding as well as micellization. In this paper the effects of 26 non electrolyte additives (including 12 alcohols, 7 glycols and 7 amides) on the association and clouding behavior of silicone surfactants (SS) in aqueous solutions have been studied. The results show that the addition of the polar organic liquid additives which are miscible with water increases the critical micelle concentrations (CMC) and cloud point of the SS, whereas the addition of the polar organic liquid additives which are partially soluble in water decreases the CMC and cloud point of SS. The change in Gibbs free energy of micellization in the presence of additives was obtained from the data on critical micelle concentrations. The influence of given additive on the micellization of SS was monitored from the changes in the free energy of micellization values for the surfactant solutions in water and water + additives. For additives belonging to a particular homologous series the effect on the cloud point and micellization is correlated to the length of the hydrophobic alkyl chain.