Fluorescence depolarization in sheared solutions of dye-tagged polymers

Abstract

The micro-Brownian motion of a polymer chain in sheared solutions has been studied by means of fluorescence depolarization. An apparatus for determining the degree of polarization of sheared solutions was designed, and measurements were made on fluorescein in aqueous hydroxyethyl cellulose solutions, both tagged to the polymer chains and freely dispersed. The degree of polarization was independent of rate of shear in the region studied, 0-10⁴ s^–1, though the flow viscosity of the solutions showed marked non-Newtonian nature. Similar behaviour was observed for concentrated solutions of dextran and polystyrene.