Kinetics of conformational changes in polyelectrolyte systems*

Equilibrium phase behavior of polyelectrolytes is well-studied in literature. The kinetics of conformational changes in such systems, however, has received sporadic attention, which has increased recently given its 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 the swelling kinetics of polyelectrolyte gels. We will present our recent results obtained from the nonlinear theory that uses the expression of osmotic stress as a function of mass and charge densities, and hence is capable of addressing arbitrarily large deformations that are beyond the scope of traditional theories with linear stress-strain relationship. Considering issues like charge-regularization and role of elasticity and electrostatics, the major results we have obtained include estimation of effective elastic modulus, time-dependency of the size, and the relaxation times of charged gels as functions of its charge content, temperature, density of cross-links, and chemical affinity of the polymer and the solvent.