Application of probe diffusion models to sphere diffusion in a rod/sphere composite liquid

Mark A. Tracy; Robert Pecora

doi:10.1117/12.148373

21 July 1993 Application of probe diffusion models to sphere diffusion in a rod/sphere composite liquid

Mark A. Tracy, Robert Pecora

Proceedings Volume 1884, Static and Dynamic Light Scattering in Medicine and Biology; (1993) https://doi.org/10.1117/12.148373
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

Five composite liquid solutions (CL1-5) were prepared consisting of silica spheres and the rigid rod polymer poly(γ-benzyl α,L-glutamate) (PBLG) in the polar organic solvent dimethylformamide. The sizes of the macromolecular components in each solution were chosen such that the sphere radius/rod length ratio decreased from CL1 to CL5. The sphere diffusion constants in the composite liquids were measured as a function of the rod concentration by dynamic light scattering. Microviscosities (η_μ ) as low as 1/2 of the solution viscosity (η) were found. The sphere diffusion constant data was fit to a stretched exponential of the form D/D_o equals exp(-αc^v) which is predicted by several models for the diffusion of spheres in polymer solutions. From these fits, we conclude (1) the stretched exponential fit is worst if η_μ < η, (2) models predicting a stretched exponential offer no explanation for η_μ < η, and (3) the experimentally determined values for v compare well to other experimental data but not to theoretical predictions.

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Mark A. Tracy and Robert Pecora "Application of probe diffusion models to sphere diffusion in a rod/sphere composite liquid", Proc. SPIE 1884, Static and Dynamic Light Scattering in Medicine and Biology, (21 July 1993); https://doi.org/10.1117/12.148373

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