The nonlinear change in conformation of polyelectrolyte macromolecules in saltless water‐organic solvent

High molecular weight polyelectrolyte: poly(dimethylaminoethyl methacrylate) [PDMAEMA] with molecular weights M W = 28.0×10 6 , 20.0×10 6 , 15.0×10 6 was investigated in dilute solution by light scattering, flow birefringence and viscometry (at different rate gradients) in a water‐acetone system by varying the weight fraction of acetone r in the mixture. At r=0.76 the polymer undergoes a reversible coil‐globule transition accompanied by a drastic decrease in intrinsic viscosity [ n ], mean‐square radius of gyration R 2 z 1/2 and second virial coefficient A 2 , with no change in molecular weight. The coil asymmetry parameter p ( p =2.5 at r=0.50) decreases with increasing r and attains unity (completely symmetrical particle) at the transition point (r=0.76). The anomalous behavior of the viscosity of PDMAEMA‐water‐acetone solutions, detected near the transition point (r=0.6+0.7), is interpreted by formation of local knots of compactization on the molecular chain under the influence of a hydrodynamic field.