Surface Activity Properties at Equilibrium of Novel Gemini Cationic Amphiphilic Compounds from Arginine, Bis(Args)

Abstract

A systematic study of the surface active properties at equilibrium (in water and in the presence of 10-2 M NaCl) of a novel class of gemini cationic surfactants from arginine is described. They are N α,N ω-bis(N α-acylarginine) α,ω-alkylidenediamides or bis(Args). Parameters studied include cmc (critical micelle concentration), pC 20 (negative log of the surfactant molar concentration, C 20, required to reduce the surface tension of the solvent by 20 mN/m), γcmc (the surface tension at the cmc), Γmax (the maximum surface excess concentration at the air/aqueous solution interface), A min (the minimum area per surfactant molecule at the air/aqueous solution interface), and the cmc/C 20 ratio (which measures the tendency of the surfactant to adsorb at the interface relative to its micellization tendency). Data on the synthesis and chemical and spectral characteristics of surfactants are also reported.

Solution Properties and Emulsification Properties of Amino Acid-Based Gemini Surfactants Derived from Cysteine

“…The concentrations used for 2C n diCys differed with alkyl chain length because of the problem of scattering intensity or solubility in water. The values of D H were 4.9 1.9 nm for 2C 10 , CMC 472 . Based on their sizes, the aggregates formed were micelles.…”

“…After removing the solvent, the residue obtained was recrystallized repeatedly from the mixture of ethyl acetate and ethanol, the mixture of ethyl acetate and acetone, and then the mixture of hexane and acetone, giving the cysteine-based gemini surfactant 2C n diCys n 10, 12, or 14 . The structures were evaluated by using 1 10 diCys may contain very little impurities like inorganic salts. However, probably, there is no influence of these impurities on the solution properties and emulsification properties because of a small quantity.…”

Synthesis and surface studies of anionic gemini surfactant in the different counter-ions

“…For gemini, several researchers have used 2 or 3 for n. The values of A cmc in aqueous solution without salt, in Table 1, are based upon n = 3, whereas in Table 2, n is assumed to be 1 in the presence of various electrolytes [17,23]. In comparison to pure G16 solutions, the G16 solutions with counter-ions have considerable preference to be adsorbed at the air/ water interface.…”

Formation of Microemulsions with Gemini-Type Surfactant.

“…X is the weight fraction of GS+hexanol in the system. W 1 Fig. 3 Phase Diagrams of (a) 3 wt% NaCl aq., (b) 1 wt% NaCl aq., (c) 0 wt% NaCl aq./GS/MEH/Dodecane Systems at 25 .…”