Date of Award

1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Paul S. Russo

Abstract

The dynamic behavior of magnetic latex particles has been explored. Polarized and depolarized dynamic light scattering from binary and ternary systems of these particles have provided rotational and translational diffusion coefficients. Microscopic views of rotational and translational diffusion of these particles are compared with macroscopic viscosity from the Stokes-Einstein equation (Chapter 2). The polymeric stabilization of magnetic latex particles has also been investigated by static and dynamic light scattering. Using the optical anisotropy of magnetic latex particles, the translational and rotational diffusion coefficients of the particles under various salt conditions were determined. The stability of the superparamagnetic latex particles depends on electrostatic repulsion and van der Waals attraction. Translational and rotational diffusion of the magnetic latex particles decrease abruptly in the high salt condition, but are recovered upon addition of a polyelectrolyte polymer. Polystyrene sulfonate sodium salt stabilizes the flocculated particles but restricts their motion. Self diffusion studies with fluorescence photobleaching recovery have been done with labeled NaPSS to verify that the stability arises from a mechanism other than conventional steric stabilization (Chapter 3). Applied magnetic fields induce the end-to-end attachment of the magnetic latex particles. Kinetic growth of these particles under a magnetic field has been studied by optical microscopy and small angle light scattering. Average cluster sizes determined from the microscopy images and the SALS patterns have been compared (Chapter 4). The polyelectrolyte studies were extended to a high strength rod-like polyelectrolyte system (PBO/MSA-MSAA). Slow polymer chain diffusion and very rapidly decaying intensity autocorrelation functions were measured by depolarized and polarized light scattering data (Chapter 5). The dynamics of trapped magnetic latex particles in porous silica gel and acrylamide gel depend on the gel structure and its viscoelastic properties. The translational and rotational diffusion of the magnetic latex particles and the ordinary latex particles inside the gel network have been investigated preliminarily with dynamic light scattering (Appendix A).

Pages

185

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