Studies on the effects of amino acids on micellization of CTAB via surface tension measurements

The effects of amino acids on the cmc of cetyltrimethylammonium bromide (CTAB) in the Tris–HCl buffer solution were studied by surface tension measurement. The results show that the effect of the additives depends on their nature and concentration at a fixed temperature. For the three amino acids, steric effect is predominant over hydrophobicity during the interaction process between them and CTAB. The cmc and surface tension at the cmc (γcmc) of CTAB in the presence and absence of glycine at different temperature decrease with the increase of temperature. The thermodynamic parameters of micellization were determined and an enthalpy–entropy compensation effect was observed for the systems. The cmc of CTAB decreases with the increasing concentration of glycine.