Interaction in Mixed Micellization of Sodium N‐Tetradecanoylsarcosinate with Ionic and Nonionic Surfactants

Abstract

The interaction of aqueous binary mixtures of an N‐acyl amino acid based anionic surfactant, sodium N‐tetradecanoylsarcosinate (C₁₄‐sarcosinate), in the presence of cationic, anionic, and nonionic surfactants has been investigated by surface tension and viscosity measurements. The cationic surfactants dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), dodecylpyridinium bromide (DPyB), and hexadecylpyridinium bromide (CPyB), the anionic surfactant sodium dodecyl sulphate (SDS), and the nonionic surfactant Triton X‐100 were used. The critical micelle concentration (CMC) values of pure surfactants and their mixtures were determined by surface tension measurements at different mixed ratios. The interaction parameters that measure the interaction between the surfactant molecules in the mixed micelle were computed by Rubingh's approach. The viscosity of the mixed systems of C₁₄‐sarcosinate with cationic surfactants (having higher chain length) at various mole fractions suggested a growth in mixed micelles with maxima at 0.4 mole fraction of C₁₄‐sarcosinate. The mixed micelles remain spherical with SDS and Triton X‐100. These changes in viscosities are due to changes in the microstructure of the mixed aggregates. Triton X‐100 shows a steep rise in cloud point in the presence of C₁₄‐sarcosinate.

Keywords:

• Mixed micelle
• interaction
• N-acylamino acids
• CMC

Acknowledgment

Financial assistance from CSIR Project No‐ 01/1827/02/EMR‐II is gratefully acknowledged.