Thermodynamics of non-ionic surface-active agent + water systems

Abstract

Measurements of water vapour pressure and heat of mixing have been made at 25°C over a range of composition for the 'octyl-and decylhexaoxyethylene glycol monoether + water systems. The condensed binary phase diagrams show that only the system given by the higher homologue forms a lyotropic mesomorphic phase (middle phase) at 25°C. In both systems, the thermodynamic properties of the solutions are determined by the interaction of the hydrophilic groups with water. The water activity and heat of mixing are smooth functions with respect to composition with no measurable discontinuities at the mesomorphic phase boundaries. The consequences of this conclusion and its relationship to the structure of middle phase are discussed.

Solid-Liquid Phase Behavior of Binary Mixture of Tetraethylene Glycol Decyl Ether and Water

“…The phase behavior of their aqueous mixtures has also attracted considerable attention in view of both a fundamental interest in colloid science and the requirement for their practical use. It has been revealed that various mesomorphic phases are formed in aqueous mixtures of these surfactants depending on the chemical structure of the species, the composition of the mixture, and temperature (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). However, the interest so far has been rather restricted to the solution phase and liquid-crystalline phases, and much less attention has been addressed to the phase behavior in a solid state.…”

Phase Behavior of Aqueous Mixtures of Some Polyethylene Glycol Decyl Ethers Revealed by DSC and FT-IR Measurements

“…The phase science of the mixture systems of this type of surfactant and water has so far been a problem attracting considerable attention in fundamental colloid science and the practical application of the surfactants (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). The highly viscous mesomorphic phases is unfavorable to transport the surfactant preparations in the industrial production process.…”

Thermodynamics of aqueous mixtures of polyoxyethene glycol monoethers V. Excess molar volumes of (n-decyl hexaoxyethene glycol monoether + water) in the vicinity of the critical micelle composition

“…On the basis of the measurements of V E m over the whole range of x we are unable to detect any discontinuity in the isotropic micellar phase to the hexagonal phase transition. If this transition is first order, as some authors (1) suggest, such a discontinuity in V m could be found by applying other volumetric techniques (18) such as those used in the study of order-disorder transition in thermotropic liquid crystals.…”

“…The phase diagram of {xCH 3 (CH 2 ) 9 O (CH 2 CH 2 O) 6 H + (1 − x)H 2 O} at the temperature 298.144 K has been reported in the literature by two independent groups. (1,2) This system exhibits lower critical solution temperature (l.c.s.t.) with a very flat minimum at T c = 332.15 K. The authors (1,2) found a substantial area (0.028 < x < 0.073) of the hexagonal phase in which lyotropic liquid crystals in equilibrium with the micellar phase are formed.…”

“…(1,2) This system exhibits lower critical solution temperature (l.c.s.t.) with a very flat minimum at T c = 332.15 K. The authors (1,2) found a substantial area (0.028 < x < 0.073) of the hexagonal phase in which lyotropic liquid crystals in equilibrium with the micellar phase are formed. Earlier measurements of vapour pressures, (1) enthalpies of mixing, (1) surface tension, (3) and light scattering (4) for the system studied are available in the literature.…”