On the theory of light and neutron scattering from droplet microemulsions

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“…The Kerr effect measurements on vesicle-like droplets could in principle serve as an alternative (to such techniques like the static and dynamic neutron or light scattering [6]) probe of the properties of the droplet surface membranes or films. In the present work the Kerr effect on dilute suspension of such (noninteracting) droplets has been described.…”

“…Note that if the entropy of mixing [11] is taken into account, −kT F ( )/(4πR 2 ) where F ( ) ≈ ln − 1 for small , should be added into the last term of Eq. (11) [6]. For the case of two-phase coexistence in microemulsions [8] Eq.…”

“…Taking into account the above discussed improvement of the theory, it can be shown that this value of the rigidity constant is essentially underestimated. Really, in our paper [6] we have related the surface parameters to the polydispersity of the droplets in radii, ε, by the following expression:…”

“…However, as discussed in Ref. [6], different techniques yield very different parameters of the surface shells. It is thus important to have adequate theoretical description of the experimental techniques that could serve as alternative probes of the vesicle membrane properties.…”

Solvent Effects on AOT Reverse Micelles in Liquid and Compressed Alkanes Investigated by Neutron Spin−Echo Spectroscopy

“…SANS has been used extensively in studying microemulsions as they exist in single and multiple phases to understand the thermodynamics and interaction energetics associated with phase transitions at various positions on the oil/water/surfactant ternary phase diagram. − SANS studies were influential in determining the structure and existence of AOT microemulsions in compressed propane and ethane. ,,,, Reverse micelle microemulsions are dynamic systems and describing their structure with SANS requires the use of a polydispersity term that accounts for the range of micelle diameters observed by the “static picture” of the entire microemulsion system. Equation 2 demonstrates the relationship between polydispersity and spherical reverse micelles where R 0 is the mean radius, R s is the radius of spontaneous curvature, and f ( φ ) is the mixing entropy per droplet as a function of the volume fraction φ . − The polydispersity equation also demonstrates the contribution of the bending elasticity k and saddle-splay elasticity k̄ and few studies have determined values of the elastic terms using SANS measurements. , Comparison of the bending elasticity terms obtained from SANS with those from alternative methods reveals significant inconsistencies which have been discussed in the literature. ,− Typical values of k are on the order of k B T or smaller; however, the values obtained by SANS in the literature are generally higher. , These inconsistencies may be a result of the static nature of the SANS measurements. , …”