Near-critical dynamical behavior of an ionic micellar solution

Abstract

Crossover critical phenomena in an aqueous electrolyte solution: Light scattering, density and viscosity of the 3methylpyridine + water + NaBr system Double critical behavior and micellar size effect in the multicomponent surfactant solution A series of experiments, static light scattering, dynamic light scattering, and shear viscosity, have been performed to study the critical properties of micellar solution of sodium dodecyl sulfate ͑SDS͒ and butanol in an aqueous solution of sodium chloride in terms of the modified dynamical droplet model. The exponents and ␥ for the long range correlation length and the osmotic compressibility were obtained as 0.736 and 1.374, respectively, in agreement with Fisher's renormalized Ising model. The experimental investigation on the dynamic critical behavior suggests that the modified dynamical droplet model, which assumes that the local fluctuations activated thermally behave as the physical clusters with a fractal dimension of d f ϭ2.49 and a polydispersity exponent of ϭ2.21, describes well the dynamical behavior of the SDS ionic micellar mixture together with an evaluation of the effective micellar size of 7-8 nm.

Synthesis and phase behavior of aqueous poly(N-isopropylacrylamide-co-acrylamide), poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) and poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate)

“…The cloud point T cp of the polymer solutions were determined at temperatures showing an optical transmittance of 50%. Dynamic light-scattering (DLS) measurements were carried out at the scattering angle of 30 for aqueous PNIPAM, PNIPAM-AAm-1, PNIPAM-AAm-2, …, and PNIPAM-AAm-6 from lower to higher temperatures using a laboratory-made light scattering apparatus [21] with a BI-9000AT correlator (Brookhaven). Vertically polarized incident light of 532 nm wavelength (a diode laser, BWT-50, B&W) were used.…”