Synthesis and Surface Properties of Anionic Gemini Surfactants having N‐acylamide and Carboxylate Groups

Abstract

A straightforward synthetic strategy to an anionic gemini surfactant having both N‐acylamide and carboxylate groups in a molecule has been demonstrated. The surface properties of the anionic gemini surfactant, such as CMC (critical micelle concentration), C20 (the concentration required to reduce the surface tension of the solvent by 20 mN/m), γCMC (the surface tension at the CMC), ∏CMC (the surface pressure at the CMC), Γmax (the maximum surface excess concentration at the air/aqueous solution interface), Amin (the minimum area per surfactant molecule at the air/water interface), and the CMC/C20 ratio (a measure of the tendency to form micelles relative to adsorbtion at the air/water interface), have been studied. The influence of the different concentrations of NaCl on the surface properties of the gemini surfactant has been discussed. The results have shown that the CMC values decreased with an increase in the concentration of NaCl indicating that the Na+ preferentially adsorbs onto the surface of the charged aggregate and facilitates the aggregate growth by suppressing the main impediment of electrostatic repulsion among head groups. Additionally, the values of Γmax are always higher in salt solutions as compared to those in pure water due to their salting out effect. The larger pC20 value indicates that the surfactant adsorbs more efficiently at the air/water interface and reduces surface tension more efficiently. In addition, the geminis in water show little or no break in their specific conductance versus surfactant molar concentration plots. This is attributable to protonation of the carboxylate group and strong Na+ release during micellization.

Krafft Temperature, Critical Micelle Concentration, and Rheology of “Pseudo‐Gemini” Surfactant Comprising Fatty Acid Soap and Bola‐Type Quaternary Ammonium Salt

“…In contrast, the CMC values of noncovalently bonded pseudogemini surfactants are higher than those reported for “true” covalently bonded carboxylate gemini surfactants with a small spacer (ethylene), such as (CH 2 ) 2 [N(COC n H 2n+1 )‐CH(COOH)CH 2 COOH]·2NaOH ( n + 1 = 12, 14, and 16, CMC = 0.0085, 0.00079, and 0.0039 mM) (Tsubone et al, ) and 1,2‐bis(N‐β‐carboxypropanoyl‐N‐alkylamino)ethane (2C n enAm, n = 12 and 14, CMC = 0.01 and 0.0026 mM) (Yoshimura and Esumi, ). The CMC values are comparable, however, to those reported for “true” carboxylate gemini surfactants with a large spacer (more than six mthylene carbons), such as N,N′‐hexamethylene‐bis(dodecylsuccinamic acid) (CMC = 0.10 mM) (Zhou et al, ). On the other hand, the CMC values of noncovalently bonded pseudogemini surfactants are noticeably lower than those of their monomers (Rosen, ), embodying the advantages of gemini surfactants.…”

Synthesis and Surface Properties of a Novel Anionic Gemini Surfactant using Dioxaoctane as a Linking Group

“…When the concentration was less than the CMC, surfactant conductivity increased rapidly with increasing concentration. When the concentration was greater than the CMC, the conductivity increased with increasing concentration, but at a slower rate (Zhou et al, ). The CMC was obtained from the turning point of the lines from the plots of specific conductance versus surfactant molar concentration.…”

“…In 2001, Dix reported a new anionic Gemini surfactant using the unsaturated succinic anhydride and diamine as starting materials for the first time (Dix, 2001;Dix & Gilblas, 2005). The critical micelle concentration (CMC) of the anionic Gemini surfactants was around 0.1 mM in aqueous solution at 20 C. On the basis of Dix's work, Zhou et al (2014) reported another anionic Gemini surfactant with saturated succinic anhydride in 2014, which showed a similar CMC. In this paper, we designed a straightforward, mildly synthetic route toward an anionic Gemini surfactant using saturated succinic anhydride and 1,8-diamino-3,6-dioxaoctane as starting materials as shown in Fig.…”

Synthesis and Properties of pH‐Dependent Gemini Surfactants Containing Multiple Carboxyl Groups

“…The hydrophobic groups are connected by a short linker at, or in close vicinity to, the headgroup (Menger and Littau, ). Due to their special structure, Gemini surfactants are superior to the corresponding monomeric surfactants in certain characteristics (Zana, ; Zhou et al, ). One of the key properties of Gemini surfactants is the remarkably low critical micelle concentration ( cmc ) in aqueous media, which enables us to reduce the total consumption of surfactants in waterborne chemical products.…”