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Results of an extensive study of dynamic polarized (VV) and depolarized (VH) Rayleigh–Brillouin light scattering in Quinoline as a function of temperature are presented. The VV spectrum is analyzed by taking into account the fine structure (shear dip) of the VH spectrum. The hypersound velocity u ( T ) and the Landau–Placzek ratio γ ( T ) have been calculated from the frequency shift of the Brillouin lines and the ratio of the integrated intensities of the non-shifted Rayleigh line to the two Brillouin lines. Under the conditions of high-purity and long equilibration times, the temperature variations of both u ( T ) and γ ( T ) show two reproducible anomalies centered at about 17 and 42 °C. We discuss an interpretation of the anomalies based on local structure changes, and possible relations of these anomalies to liquid–liquid phase transitions in equilibrium liquids.

We present a lattice model based on two n→0 spin vectors, capable of treating the thermodynamics of living networks in micellar solutions at any surfactant concentration. We establish an isomorphism between the coupling constants in the two spin vector Hamiltonian and the surfactant energies involved in the micellar situation. Solving this Hamiltonian in the mean-field approximation allows one to calculate osmotic pressure, aggregation number, free end and cross-link densities at any surfactant concentration. We derive a phase diagram, including changes in topology such as the transition between spheres and rods and between saturated and unsaturated networks. A phase separation can be found between a saturated network and a dilute solution composed of long flexible micelles or a saturated network and a solution of spherical micelles.

We discuss the static and dynamic critical behavior of binary solutions of water with some alkyl-oxyethylene-glycol monoether (CiEj) and of di 2 ethylhexyl sodium sulfosuccinate (AOT)-water-decane ternary microemulsion systems. Extensive sets of measurements of the scattered light intensity, of the order-parameter fluctuations time correlation function, and of the shear viscosity, have been performed for different systems. In most of the cases our data sets show systematic deviations from the behavior usually observed for molecular binary fluids. We show that generalized hydrodynamics cannot account for these deviations. A modified version of the Sorensen et al. (1976) dynamical droplet model has been worked out. This model which assumes that the physical clusters formed close to the critical point can be treated like percolating aggregates, and which includes the finite size of the monomers, very well accounts for all our experimental results.

A theory for static and dynamic light scattering from micellar and microemulsion systems near the critical point is given which incorporates the universality of critical phenomena in fluids and the finite size effect of the constituent particles in the system. This theory reduces to the Ornstein-Zernike formula for the static light scattering intensity and the Kawasaki mode-coupling result for the line width of the dynamic light scattering in the limit when the size of the particles is vanishingly small compared to the wavelength of the probing light. When this is not the case the critical dynamics shows considerable deviation from the mode-coupling theory and the order parameter fluctuation exhibits non-exponential relaxation. The main ingredient of the theory is the recognition of the fact that the physical particle cluster size distribution near the critical point is nearly identical to the standard percolation cluster size distribution characterised by universal values of the fractal dimension D = 2.49 and of the polydispersity index τ = 2.21. We analysed light scattering data from several micellar solutions and a microemulsion system to support the validity of this theory and establish firmly that the underlying critical phenomena are indeed universal.

We present a corresponding states analysis of existing data on sound velocity, transport coefficients and intermolecular interaction times of a number of simple fluids. With appropriate choices of parameters for the intermolecular pair potential, such properties as the adiabatic sound velocity, the shear and bulk viscosities, the thermal conductivity and the intermolecular interaction time can be reduced along the liquid-vapor equilibrium curve. Deviations from the simple law of corresponding states are most pronounced for the transport properties, indicating a stronger sensitivity of the dynamical properties to the interaction potential and the molecular structure.