Kinetics of conformational changes in polyelectrolyte systems*

Interest in the kinetics of conformational changes in polyelectrolyte systems, unlike their equilibrium phase behavior, has been sporadic, but has received recent attention given their relevance to biological problems like protein-folding or biomedical processes like drug-delivery. Our group has been working on studying the time-dependent, inhomogeneous profiles of physical variables, such as mass and charge densities and osmotic stress, related to such kinetic processes. We will present our understanding that we have developed on this topic over the past two years, especially for two systems - polyelectrolyte gels, and single, isolated, polyelectrolyte chains. Our study considers important issues like charge-regularization and role of elasticity and electrostatics to modulate the spatially varying osmotic forces, which drive these conformational changes. The major results we have obtained include estimation of effective bulk modulus of charged gels, time-dependency of the size of a gel or a single chain as a function of its charge content, temperature, density of cross-links, and chemical affinity of the polymer and the solvent.