Effect of urea and amides on the micelle formation of anionic and cationic soaps

Summary The effect of urea, formamide, acetamide and lauric acid diethanolamine condensate on the micelle formation of alkyl-aryl sulphonates and quaternary ammonium salts was studied by p_H-metric and conductometric measurements. It was found that the presence of these additives increases the c.m.c. of both anionic and cationic soaps in the order SPSA > STSA > SXSA and CTMAB > CPB respectively. The striking difference between the effect of urea and amides was that concentration higher than 1 M of the latter did not bring further change in c.m.c. whereas changes with urea could be observed upto 6.0 M. Lauric acid diethanol amine condensate could bring about these changes at much lower concentration. The results have been explained in terms of break in water structure.