Proton NMR studies on the structure of water in ionic and nonionic water‐in‐oil microemulsions

Abstract

The structure of water present in water‐in‐oil microemulsions of anionic magnesium bis(2‐ethylhexyl) sulfosuccinate in C6D6, cationic cetyldimethylbenzylammonium chloride in C6D6, cetyldimethyl‐3‐phenylpropylammonium chloride in chlorobenzene, and nonionic polyoxyethylene (4) dodecyl ether in n‐heptane was probed by 1H NMR. Chemical shifts of solubilized H2O‐D2O, and of surfactant discrete protons were determined, at fixed [water]/[surfactant] ratios, as a function of the deuterium content of solubilized water. Chemical shift data were used to calculate the so called “fractionation factor”, φ, of the aggregate‐solubilized water. Calculated φ for the different systems are unity, showing that micellar water, although different from bulk water, does not seem to coexist in “layers” of different degrees of structure, as suggested, e.g., by the two‐state water solubilization model.

Solubilization of Pure and Aqueous 1,2,3-Propanetriol by Reverse Aggregates of Aerosol−OT in Isooctane Probed by FTIR and 1H NMR Spectroscopy

“…Other models depicting the presence of only two or four types of water have also been suggested 4b. Our results, and those of others on ionic and nonionic reverse aggregates, ,,22b,, related micellar systems, − and theoretical calculations on the molecular dynamics of water, indicate that treatment of experimental spectroscopic data in terms of the coexistence of structurally different water layers within the pool is probably an oversimplification. Solubilized water is present as a pseudophase whose properties change continuously as more water is added.…”

1H NMR Studies of Aerosol-OT Reverse Micelles with Alkali and Magnesium Counterions: Preparation and Analysis of MAOTs

“…Because NMR is such a common analysis technique, it would be desirable to find a way to use it to estimate the amount of residual water in these samples. Other researchers have reported using NMR to gauge the amount of water in AOT samples. ,,– With two additional independent measures, we explored the effectiveness of proton NMR for determining water content in the MAOT samples.…”

Reações de transferência de acila em microemulsões água/óleo: hidrólise de benzoatos de fenila catalisada pelo ânion o-iodosobenzoato.

“…(EICKE e KVITA, 1984), ou então, haveria uma menor interação entre as moléculas de água e de tensoativo (EL SEOUD et al, 1996). PRINCE, 1977).…”

“…Estudos recentes de RMN (EL SEOUD et al, 1994-b;EL SEOUD et al, 1996) e de IV (CHRISTOPHER et al, 1992) estão de acordo com a idéia da presença de um só tipo de água solubilizada pelo agregado inverso, e cujas propriedades variam continuamente em função do aumento de W/S. Não é necessário atribuir a mudança de inclinação nos gráficos de certas propriedades com o W/S, que é observada quando se passa de MI para µE A/O, à formação de "água livre" no agregado.…”

“…Não é necessário atribuir a mudança de inclinação nos gráficos de certas propriedades com o W/S, que é observada quando se passa de MI para µE A/O, à formação de "água livre" no agregado. Isso pode simplesmente refletir o decréscimo nas interações águatensoativo após a completa hidratação de seus grupos polares (EL SEOUD et al, 1996).…”