title: Microrheology of wormlike micellar fluids from the diffusion of colloidal probes.
abstract: The microrheology of cationic micellar solutions has been investigated as a function of added organic salts using quasielastic light scattering (QELS). Two organic salts, sodium p-toluene sulfonate and sodium salicylate, were used to induce microstructural changes in cetyl trimethylammonium bromide (CTAB) micelles. The mean-squared displacement (MSD) of polystyrene probe particles embedded in CTAB micellar solutions was monitored by QELS in the single-scattering regime. Through the use of the generalized Stokes-Einstein relationship, the frequency-dependent complex shear moduli of each fluid were estimated from the Laplace transform of the corresponding MSD. The salt-induced transition from nearly spherical to elongated wormlike micelles and consequent changes in fluid response from viscous to viscoelastic are clearly captured by microrheology.
authors.affiliation: Novel Materials and Structural Chemistry Division and Applied Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India. hassan@apsara.barc.ernet.in
authors.forename: P A
authors.initials: PA
authors.lastname: Hassan
authors.forename: K
authors.initials: K
authors.lastname: Bhattacharya
authors.forename: S K
authors.initials: SK
authors.lastname: Kulshreshtha
authors.forename: S R
authors.initials: SR
authors.lastname: Raghavan