Studies of Conformational Changes and Intermolecular Interactions in Dilute Solutions of Partially Hydrolyzed Polyacrylamide by Optical Mixing Spectroscopy

Abstract Moderately concentrated aqueous solutions of certain high molecular weight polyelectrolytes exhibit complex molecular relaxation modes in the range of 1 to 105 sec−1 which confer useful commercial or biological properties. Although many different kinds of molecular relaxation phenomena have been proposed as causing the various unique properties of such solutions, the relative importance of the various modes remains unanswered mainly because of the lack of any accurate experimental means of studying these events. We describe a new laser light scattering technique which provides such a probe. We have used this method to study molecular dynamics, especially molecular transport processes, in dilute aqueous solutions of a partially ionized high molecular weight polyacrylamide. Two kinds of diffusion mode of the polymer are observed. This paper reports studies of the effect of ionic strength, polymer concentration and temperature on the slow diffusion mode.