Formamide, a water substitute XIV (1) waterless microemulsions 8. Structural analysis by X-ray scattering of CTAB aggregates in formamide and in the microemulsion system (formamide, CTAB, isooctane, 1-butanol)

Abstract

X-ray scattering was used to analyse the structures of aggregates of CTAB in various formamide-containing media.Firstly, CTAB micelles were detected in formamide solutions. A spherical micelle model was proposed; at values close to the CMC, smaller micelles were observed in formamide than in water.Secondly, the structure of microemulsions in the isooctane-rich zone of the system (formamide/CTAB = 2, isooctane, 1-butanol) was studied by X-ray scattering. The structure was found to be quite different in this zone from that normally observed in aqueous microemulsions. Structures compatible with small filaments of formamide were detected. The results were related to previous measurements of electrical conductivity.

SANS studies of the effects of surfactant head group on aggregation properties in water/glycol and pure glycol systems

“…Micelle and liquid crystal formation has been reported in solvents such as ethylene glycol (EG) [15], glycerol [2,16,[26][27][28], formamide [4,[17][18][19][20][21]29], and hydrazine [22,23]. The glycol solvents have high cohesive energies and dielectric constants (ε r (EG) = 53 and ε r (PG) = 30), and hydrogenbonding properties, which are believed to be essential requirements for promoting micellization [24].…”

Phase behavior of mixtures of polyoxyethylene(10) stearyl ether (Brij-76), 1-butanol, isooctane, and mixed polar solvents

“…Microemulsions were formulated by replacing water with other nonaqueous polar solvents such as formamide (FA), N,N -dimethyl formamide (DMF), ethylene glycol (EG), propylene glycol (PG), and glycerol (GLY) [20][21][22][23][24][25][26][27][28][29][30][31]. Among these, much attention has been focused on FA, since it is sparingly soluble in oils and its presence decreases the hydrophobicity of the surfactants [32,33].…”

Thermodynamic properties of micellization of sodium dodecyl sulfate in binary mixtures of ethylene glycol with water

“…There has recently been much research dealing with the effects of nonaqueous polar solvents on the formation of cationic micelles (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Micel!e or liquid crystal formation has been reported to occur in such solvents as hydrazine (3,4), glycerol (5,6), ethylene glycol (7,8), and formamide (9)(10)(11)(12)(13)(14)(15)(16)(17)(18), where all of the aforementioned solvents have high cohesive energy, dielectric constant, and a high degree of hydrogen bonding. Evans and co-workers (19) have indicated that the ability of a solvent to form hydrogen bonds is a necessary condition of micelle formation.…”