The aqueous Triton X-100 - Dodecyltrimethylammonium bromide micellar mixed system. Experimental results and thermodynamic analysis

TL;DR

This study investigates the micellization behavior of a Triton X-100 and Dodecyltrimethylammonium Bromide mixed surfactant system using experimental techniques and thermodynamic analysis, revealing composition-dependent micelle properties.

Contribution

It provides new insights into the thermodynamic and micellar behavior of Triton X-100 and DTAB mixtures across different compositions, highlighting abrupt changes at specific mole fractions.

Findings

Micelle composition varies with DTAB mole fraction.

Distinct micellar behaviors observed below and above certain composition thresholds.

Thermodynamic analysis explains changes in micelle size and mobility.

Abstract

The micellization process of the aqueous mixed system Triton X-100 (TX100)-Dodecyltrimethylammonium Bromide (DTAB) was studied with a battery of procedures: surface tension, static and dynamic light scattering and ion-selective electrodes. Results were also analysed with two thermodynamic procedures. The system shows some changes in its behaviour with changing the mole fraction of DTAB, $\alpha_{DTAB}$, in the whole surfactant mixture. For $ \alpha_{DTAB} < 0.40$ micelles are predominantly TX100 with scarce solubilized DTA+ ions, and TX100 acts as a nearly ideal solvent. In the range $0.50 < \alpha_{DTAB} < 0.75$ it seems that none of the components acts as a solvent, and above $\alpha_{DTAB} > 0.75$ there are abrupt changes in the size and electrophoretic mobility of micelles. These phenomena have been interpreted in the light of the thermodynamic results and some TX100-ionic surfactant mixtures of literature.