Aggregation of water-soluble conjugated polymers in couette shear flow

Abstract

Aqueous solutions of the conjugated polymer poly(2,5-disulfopropoxy-1,4- phenylene vinylene) (DPS-PPV) blended with poly(vinyl alcohol) (PVA) have been exposed to Couette shear flow and studied using fluorescence techniques. Significant aggregation of the DPS-PPV and PVA molecules occurred during shear exposure, resulting in an 80% decrease in solution fluorescence intensity and formation of visible polymer particles. The aggregation process caused a separation of the DPS-PPV molecules where the fluorescence of the aggregated particles had a red-shifted emission peak at a wavelength of 594 nm, and the rsolution had a blue-shifted emission at 513 nm, as compared to an initial emission peak at..