Tuning the solubilization behavior of the CTAB/C < inf > 9 < /inf > OH-C < inf > 12 < /inf > OH micellar system with quaternary ammonium salts

Abstract

In this paper we investigated the effect of quaternary ammonium bromide, R4NBr(R = methyl, ethyl, propyl, butyl) on the micellization of the CTAB/long-chain alcohol (C9OH-C12OH) micellar system using viscosity, rheology, dynamic light scattering (DLS), and cryo-TEM analysis. The results indicates that, apart from concentration (C0), and chain length of alcohol (n), micellar properties of the CTAB/R4NBr/alcohol system showed a strong dependence on alkyl chain length of R4NBr. The viscosity behavior of CTAB/R4NBr with C0 was similar to our previous studied system, CTAB/KBr/alcohol, and is attributed to alcohol induced morphological transition. The viscosity, rheology, and DLS analysis reveal the dependence of n on the micellar growth of the CTAB/R4NBr/alcohol system. The result showed tetra butyl ammonium bromide (Bu4N+) as least effective to induce micellar growth in the CTAB/alcohol system compared to other quaternary ammonium salts. This is discussed on the basis of change in solubilization behavior with the chain length of R4NBr. The cryo-TEM analysis of the CTAB/R4NBr/alcohol micellar system showed vesicles to short rod-like micelle transition on changing R from methyl to butyl, confirming the effectiveness of quaternary ammonium bromide in tuning morphological transition in the system.