Effect of tetraalkylammonium bromides on the micellar behaviour of ionic and non-ionic surfactants

715-721Effect of tetraalkylammonium bromides (methyl, ethyl, n-propyl and n-butyl) on the surface activity and micellar behaviour of sodium dodecyl sulfate (NaDS), tetradecyltrimethyl- ammonium bromide (C14TABr) and dodecyl decapolyethylene glycol ether (C12E10) has been examined by surface tension, dye solubilization, viscosity and cloud point measurements. Strong decrease in critical micelle concentration (CMC) and increase in solubilization power has been observed for NaDS: the effect is more with longer tetraalkyl salts. These salts also decrease the CMCs of C14TABr, while the CMCs of C12E10 remain practically unaffected even up to 0.1 M concentration. However, cloud point (CP) of C12E10 increases in the presence of these salts except in tetramethylammonium bromide where it decreases above 0.05 M. Viscosity results indicate the micellar growth for NaDS and tetrabutylammonium bromide. The micellar solution of NaDS exhibits a cloud point phenomenon in the presence of tetrabutylammonium bromide. The results are discussed in the light of charge and hydrophobicity of tetraalkylammonium salts