COIL-GLOBULE TRANSITION IN SODIUM POLY(2- ACRYLAMIDO-2-METHYLPROPANE SULFONATE) IN AQUEOUS ACETONE SOLUTION

Sodium poly(2-acrylamido-2-methylpropane sulfonate) (M(w) = 3.6 x 10(6 )) in aqueous acetone solutions with a variable acetone content was ex amined using light scattering, flow birefringence, diffusion, and visc ometry. As the weight fraction of acetone in solution increases, the m acromolecules sustain a reversible transition from the random coil con formation to the globular conformation. This transition is accompanied by abrupt decrease in intrinsic viscosity, mean-square radius of gyra tion, hydrodynamic radius, second virial coefficient, and asymmetry of macromolecular shape. Moreover, the system remains a true molecular s olution. As a result of the transition, the volume of macromolecule de creases by more than 10(3) times, and the density of the resultant sph erical particle approaches the density of globular proteins.