Micellization of Carboxylic Acid Gemini Surfactant and Its Interaction with Amino Acid Surfactant in Aqueous Solution

Abstract

AbstractThe carboxylic acid‐type Gemini surfactant (CGS12) was synthesized, and its micellization in aqueous solution at different pH values at 25.0 °C was investigated. The results show that the critical micelle concentration (CMC) of CGS12 at different pH values is only 10−6 order of magnitude, and the pH has little effect on the CMC. Moreover, the interaction of CGS12 with amino acid surfactant of sodium N‐lauroyl sarcosinate (SLS) at 25.0 °C and pH 7.0 was investigated using surface tension, dynamic light scattering (DLS), cryogenic transmission electron microscopy (Cryo‐TEM), and Ross–Miles foam measurements. The CGS12/SLS mixture shows a low CMC, and as a whole the CMC value becomes smaller with increasing molar fraction of CGS12 (XCGS12). Under different XCGS12, the mixtures form soluble aggregates with different hydration radii (Rh). Moreover, the mixture aggregates are mainly in the form of vesicles. The foaming height of CGS12 is worse than that of SLS, but the CGS12/SLS mixture has good foaming stability. This work reveals that the surfactant mixture has good surface activity and good foam stability.