Droplet and bicontinuous structures in microemulsions from multicomponent self-diffusion measurements

Abstract

the region of the respective kinks, 20-22 Á1 2 34567/mol and surface pressure ca. 15 dyn/cm, the viscosities increase 20-fold to ca. 20 (mdyn s) / cm. The viscosity displayed by stearic acid appears to arise principally from tail-group entanglement.15 The viscoelasticity observed with the fatty alcohols, with dipalmitoyl lecithin, and with stearic acid on water containing trivalent ions may be interpreted as showing the influence of the head group interaction mediated by the substrate.2,15•17 Valinomycin is disklike with very short pendant groups; neither stearic effects nor van der Waals attraction of the valyl groups appear to contribute to the viscosity. On the other hand, one would expect the polar group interaction might. Clearly, the factors contributing the viscoelastic behavior of monolayers are more subtle than expected.In conclusion, the work presented here establishes that monolayers of valinomycin have an anomalously low vis-

Dependence of the activity of a rhizopus lipase on microemulsion composition

“…Components diffusing in a continuous medium should have diffusion coefficients in the same order of magnitude as in neat liquids. Components confined in discountinuous domains show reduction in self-diffusion coefficients by at least one order of magnitude [12,13]. The D-values of Table I are, consequently, typical of w/o type microemulsions.…”

Middle Phase Electrochemistry of Two Pentacyano(L)Ferrates(II)

“…The scan rate range used was from 10 to 100 mV s -1 , with an increment of 10 and the domain potential from 0.0 V to 0.6 V, with first scan in the anodic direction. Microemulsions were prepared as indicated in a standard recipe, 9 the typical content of the three phase system being: water (4.68 g), toluene (4.625 g), NaCl (0.30 g), sodium dodecyl sulfate (0.199 g), 1-butanol (0.396 g), and appropriate amount of Na 3 [Fe(CN) 5 -(4,4'-bpy)] or Na 3 [Fe(CN) 5 (NH 3 )] calculated for concentration of 1 mmol dm -3 referred to the amount of water. The sodium chloride (1.1 mol dm -3 solution, calculated to the amount of water) plays the indifferent electrolyte role both in the "microscopic aqueous phase" and "water phase".…”

“…Several electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), rotation disk electrode voltammetry (RDEV) and chronocoulometry (CC), electrical conductivity and so on, involving an electroactive compound and an appropriate electrode, have been used for the study of physico-chemical properties of these systems. In the present work, it was chosen a MPME obtained by using wellknown standard recipe 9 from an initial system consisting of water, toluene, sodium dodecyl sulphate as surfactant, 1-butanol as cosurfactant, and sodium chloride as supporting electrolyte. This system leads to three macroscopically separated phases (from the upper to the lower phase): a "toluene (organic) phase", a "middle phase" (MP) and a "water (aqueous) phase" (W) which is saline in fact, due to the used sodium chloride.…”

Mesostructured Polymer Materials Based on Bicontinuous Microemulsions

“…47 In principle, the diffusion coefficients in a homogeneous solution should be independent of the type of electrode. However, the D app values obtained using the hydrophilic ITO and lipophilic pyrolytic graphite (PG-b) electrodes were less than half of those obtained with the amphiphilic Au electrode.…”