Light Scattering Measurements on Solutions of Some Quaternary Ammonium Salts

The general fluctuation theory for multicomponent systems has been applied in order to make corrections for the charge effect on systems of colloidal electrolytes where the gegenions and simple cations may have any valence. The basic equations of Prins and Hermans and Princen and Mysels were used for this derivation. The aggregation number and apparent charge were calculated from turbidity measurements on decyl-, dodecyl-, tetradecyl-, and hexadecyltrimethylammonium sulfate in different concentrations of Na₂SO₄, MgSO₄, and La₂(SO₄)₃ solutions and on dodecyltrimethylammonium bromide in the KBr, CaBr₂, and LaBr₃ solutions. The data indicate that the nature and concentration of the gegenion determine the size and charge of the micelle whereas the nature and concentration of the simple cation of the added electrolyte has little or no effect.