THE NONLINEAR CHANGE IN CONFORMATION OF POLYELECTROLYTE MACROMOLECULES IN SALTLESS WATER-ORGANIC SOLVENT

High molecular weight polyelectrolyte: poly(dimethylaminoethyl methacr ylate) [PDMAEMA] with molecular weights M(W)=28.0x10(6), 20.0x10(6), 1 5.0x.10(6) was investigated in dilute solution by light scattering, fl ow birefringence and viscometry (at different rate gradients) in a wat er-acetone system by varying the weight fraction of acetone gamma in t he mixture. At T=0.76 the polymer undergoes a reversible coil-globule transition accompained by a drastic decrease in intrinsic viscosity [n ], mean-square radius of gyration <R(2)>(1/2)(z) and second virial coe fficient A(2), with no change in molecular weight. The coil asymmetry parameter p (p=2.5 at gamma=0.50) decreases with increasing gamma and attains unity (completely symmetrical particle) at the transition poin t (gamma=0.76). The anomalous behavior of the viscosity of PDMAEMA-wat er-acetone solutions, detected near the transition point (gamma=0.6+0. 7), is interpreted by formation of local knots of compactization on th e molecular chain under the influence of a hydrodynamic field.