Doctoral Dissertations

Date of Award

8-2001

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

W. Alexander Van Hook

Committee Members

Jeffrey Kovac, Lee Magid, Paul Phillips

Abstract

Second virial coefficients (A2) of dilute polystyrene (PS) solutions in good, theta (θ) and poor solvents have been measured as a function of applied pressure using membrane osmometry and static light scattering. Membrane osmometry arid static light scattering equipment, designed to function at pressures in the range (0.1 ≦ P/MPa ≦ 6.0)and (0.1 ≦ P/MPa ≦ 35.0), respectively, have been used in these measurements, and the resulting pressure coefficients (dA2/dP) are measures of the effect of pressure on solvent quality. For the system PS/toluene, membrane osmometry and SLS-obtained values ofdA2/dP are compared.The effect of polymer architecture on the second virial coefficient has also been studied with static light scattering measurements on linear(L)-star(S) polystyrene solutions at atmospheric pressure. Second virial cross coefficients between linear and star polystyrenes of similar molecular weight (A2(l-s)) quantify the extent of linear-star PS interaction in good,θ , and poor solvents. Linear-star polystyrene interactions are preferred to polystyrene-solvent interactions in the good solvent (toluene). However, in θ (cyclohexane) and poor (MCH) solvents, there is no difference between linear-star and polystyrene-solvent interactions.

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