EFFECT OF HYDRODYNAMIC FIELD OF THE CONFO RMATION OF POLYELECTROLYTE IN THE COIL-GLOBULE TRANSITION REGION

The effects of solution concentration, solvent composition, and veloci ty gradient on the kinetics of coil-globule transition were studied fo r three samples of high-molecular-mass polyelectrolyte poly(dimethylam inoethyl methacrylate) (M(w) = 28 x 10(6), 20 x 10(6), and 15 x 10(6)) . Variation of reduced viscosity with composition of water-acetone sol vent gamma (gamma is the fraction of acetone in the solvent) and shear gradient g was studied in the range of solution concentrations extend ing from 6 x 10(-2) to 5 x 10(-4) g/dl. At g approximate to 1000 s(-1) and gamma less than or equal to 0.50, the plot of reduced viscosity v ersus concentration is linear, whereas, at gamma > 0.50 in the concent ration range below that conforming to the criterion c[eta] approximate to 1, the viscosity drastically decreases, and the corresponding plot deviates from linearity. This phenomenon may be related to the rearra ngement of intra- and intermolecular interactions when concentrations at which the number of intermolecular contacts significantly decreases are attained and to the formation of local compaction nodes on a macr omolecular chain induced by the applied hydrodynamic field. For small g, the dependence of reduced viscosity on concentration is most pronou nced at gamma = 0.50; as gamma increases, the dependence gradually bec omes less prominent. At gamma = 0.75, the examined polyelectrolyte und ergoes the coil-globule transition, and the magnitude of intrinsic vis cosity is independent of the velocity gradient.