Micellization and Adsorption Properties of Novel Zwitterionic Surfactants

Abstract

A series of novel zwitterionic surfactants each with two hydrophilic and two hydrophobic groups in the molecule (so-called heterogemini surfactants) has been synthesized. One of the hydrophilic groups is a phosphodiester anion and the other is a quaternary ammonium salt. Two methylene groups separate the two headgroups. The critical micelle concentration values of the surfactants were determined using du Nouy tensiometry and steady-state fluorescence and are of the order of 10 -5 M. Very low surface areas per molecule were observed suggesting that the monolayer formed is extremely tightly packed. NMR self-diffusion measurements gave information about the micelle size distribution. A broad distribution of self-diffusion coefficients was observed and indicated that the time scale of monomer-aggregate and/or aggregate-aggregate exchange is slow compared to the NMR time scale used (100 ms). A mean aggregate size of about 55 nm is obtained for one sample. Adsorption of the gemini surfactants at hydrophilic and at hydrophobized silica was studied by reflectometry. The more symmetrical gemini surfactants gave very low values of surface area per molecule on the hydrophobic surface, indicating a very tight packing of surfactant molecules. At higher surfactant concentrations all gemini surfactant gave very high adsorbed amount, most probably due to formation of aggregates at the surface.

Diester-containing Zwitterionic Gemini Surfactants with Different Spacer and Its Impact on Micellization Properties and Viscosity of Aqueous Micellar Solution

“…Unlike the synthesized bispyridinium gemini surfactants reported by Fisicaro et al, amin values of these surfactants increases with increasing spacer length 28,29 . Such a pattern of increase in a min values with increasing spacer length was also observed by Menger et al 22 for linear chain length zwitterionic gemini analogues and Zana et al 30 for gemini quaternary ammonium surfactants. The prime factor responsible for the deviation of a min values with spacer is the balance attractive interactions between tails and repulsive interactions between heads suggested by a theoretical model 31,32 .…”

“…Jaeger et al in 1996 gives the first report on anionic and cationic headgroups based zwitterionic geminis 15 . This ideas was followed by Menger in 1999Menger in , 2001Menger in -2003, who synthesized a great variety of anionic-cationic headgroups gemini surfactants 16, 22 24 .…”

Synthesis and aqueous solution properties of homologous gemini surfactants with different head groups

“…However, new classes of gemini surfactants have emerged and have attractive attention: dissymmetric gemini surfactants with hydrocarbon chains of different length and with two identical head groups [21][22][23][24][25][26][27][28] and asymmetric ones with two identical hydrocarbon chains and two different hydrophilic head groups [29][30][31][32][33][34]. The research on asymmetric gemini surfactant was less documented.…”

“…The research on asymmetric gemini surfactant was less documented. To our knowledge, Holmberg team [30][31][32][33][34][35] pioneered research on the properties of asymmetric gemini surfactant in solutions. They mainly studied the surface properties and adsorption characters of zwitterionic gemini surfactant at the air-water and solid-water interfaces.…”

Stabilization of Latex by Heterogemini Surfactants

“…The geminis also pack efficiently into micelles, giving very low values of critical micelle concentration (CMC) and very low values of surface tension at the CMC (between 26 and 29 mN/m) (2). Due to the opposite charge of the polar headgroups, we refer to the compounds as heterogemini surfactants.…”