Light Scattering, Rheo-Optical, and Rheological Studies on Concentrated Polymer Solutions

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This study comprises four distinct areas of investigation: (1) Static and dynamic light scattering on aligned nematic solutions of a rodlike polymer, and rheological and rheo-optical studies on aligned and unaligned nematic solutions of the same solutions; (2) Similar studies on the nematic phase of a thermotropic copolymer, as a function of temperature; (3) Static and dynamic light scattering, and rheological studies on moderately concentrated solutions of polystyrene in decalin; and (4) Static and dynamic light scattering on dilute solutions of polymers prone to intermolecular association. In the first study, the Leslie viscosities, the Frank curvature elasticities, and the order parameter will be determined over a range of chain length and polymer concentration. These parameters will also be used in the analysis of nonlinear rheological behavior in fast flow behavior. In the second, a preliminary study will be undertaken to evaluate the feasibility of the scattering studies to determine certain Leslie viscosities and Frank elasticities on a solvent-free aligned nematic polymer. In the third, the thermodynamics and chain dynamics will be studied over a range of conditions, from the Flory Theta state to "good solvent" conditions. The appearance of relaxation in the dynamic scattering due to chain entanglements will be of special interest. Finally, in the fourth, the possibility that certain thermochromic effects in dilute solution are linked to (metastable) intermolecular association will be investigated. This research aims to clarify the solution behavior of various types of important polymers, especially those able to form liquid crystals.