Aggregation properties of the cetyltrimethylammonium bromide and Triton X-100 mixture with ethanol in aqueous media

• Ethanol CAC does not depend on concentration and composition of surfactant mixture.
• Ethanol strongly affects the CMC of surfactant mixture.
• Surfactant molecules aggregate only below ethanol CAC.
• TX-100 affects conductivity of water + ethanol solution of TX-100 + CTAB.

The surface tension, density, dynamic viscosity and specific conductivity measurements of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX-100) and cetyltrimethylammonium bromide (CTAB) mixture with ethanol were carried out in the range of the total concentration of TX-100 and CTAB mixture from 1 × 10−6 to 1 × 10−2 M and in the whole range of ethanol concentration. In the surfactant mixture the mole fraction of TX-100 was equal to 0.2, 0.4, 0.6 and 0.8, respectively. From the obtained results, the critical aggregation concentration (CAC) of ethanol and the critical micelle concentration (CMC) of the TX-100 and CTAB mixture were established. It appeared that the CAC practically does not depend on the concentration and composition of the TX-100 and CTAB mixture. The CMC of the surfactant mixture was detected only in the range of ethanol concentration from 0 to its CAC. The changes of CMC in this concentration range go through minimum at certain ethanol concentration. These changes were discussed in the light of the synergetic effect in the mixed micelle formation. The composition of the micelles, the parameter of the intermolecular interaction, the activity coefficient and the aggregation number were also established.

The influence of TX-100 on the specific conductivity of CTAB in the mixed water + ethanol solvent.Figure optionsDownload as PowerPoint slide