Diffusion of polystyrene latex spheres in linear polystyrene nonaqueous solutions

Abstract

The diffusion of highly cross-linked, nearly monodisperse polystyrene latex spheres of 0.2-/tm radius in the presence of linear polystyrene as the matrix polymer in the moderately good solvent JV.1Vdimethylformamide at 25 °C was determined by quasi-elastic light scattering as a function of matrix concentration and molecular weight. This is the first report of a latex probe in trace amounts diffusing in an organic solvent, and with a matrix polymer chemically similar to the probe. The latex diffusion diminished monotonically with matrix concentration, which varied from moderately dilute solutions into the semidilute regime up to a matrix concentration of 8 times c*. Stokes-Einstein behavior was observed at all matrix concentrations and for both matrix molecular weights (2.15 x 10s and 1.1 X 106), within experimental error. In the semidilute region the entanglement relaxation was always much faster than probe motion. The diffusion data fit the scaling law D/D<¡ = exp(-ac'Af1'), with v equal to 0.99 and y equal to 0.49. Comparison is made to diffusion of latex probes in aqueous dispersants, and of silica probes in organic dispersants.

A Mathematical Explanation of an Increase in Bacterial Swimming Speed with Viscosity in Linear-Polymer Solutions

“…• The diffusion and sedimentation of microspheres in polymer solutions generally follow "Stokes-Einstein behavior," i.e., f ϭ Ϫ6 * trans a, where f is a modified Stokes friction factor, a is the radius of the sphere, and * trans is the effective viscosity that is dependent on the concentration, molecular weight and morphology of the polymer, the sphere size, and so on (Kluijtmans, et al, 2000;Turner and Hallett, 1976;Yang and Jamieson, 1988;Brown and Rymden, 1988;Phillies et al, 1989;Onyenemezu et al, 1993;Bu and Russo, 1994); • The rotations of bacterial tethered cell in methylcellulose solutions are faster than those in Ficoll solutions at the same viscosities (Berg and Turner, 1979). The measurement of the rotational Brownian motion of globular proteins in dextran solutions indicates that the effective viscosity is expressed as * rot ϭ 0 (/ 0 ) q , where and 0 are the macroviscosities of polymer solution and water as mentioned above, and q is smaller than unity and is distinctly polymer-and protein-dependent (Lavalette et al, 1999).…”

Diffusion behavior of lipid vesicles in entangled polymer solutions

“…The rheological behavior and dynamics of such complex fluids have many interesting and unusual features and have been extensively investigated. Tracer diffusion studies using dynamic light scattering (DLS) of spherical probe particles have been employed to study the properties of the polymer solutions and gels in which the particles are incorporated (Brown and Rymden, 1988;Zhou, 1989, 1990;Cooper et al, 1991;Lin and Phillies, 1984;Nehme et al, 1989;Onyenemezu et al, 1993;Phillies, 1990;Phillies et al, 1987;Reina et al, 1990;Tracy and Pecora, 1992;Won et al, 1994). In biological systems, tracer diffusion has been used to determine state of aggregation and effective viscosity of the macromolecular solution (Madonia et al, 1983;San Biagio et al, 1991).…”

Translational and rotational diffusion of flexible PEG and rigid dendrimer probes in sodium caseinate dispersions and acid gels

“…Accordingly, the topic has attracted much experimental and theoretical attention. Most studies have focused on the translational diffusion of tracers, commonly measured with dynamic light scattering, fluorescence recovery after photobleaching, and pulsed‐field nuclear magnetic resonance . Although various theoretical models for translational diffusion of tracers in polymer matrices have been proposed, the mechanisms of retardation are still incompletely understood.…”