Counterion condensation and rapid transport of polyelectrolytes through aqueous polymer solutions

A rapid transport of polyacrylates through aqueous dextran solutions was reported. The transported amount Q linearly increased with time t instead of t1/2. The rapid transport is associated with the formation of finger-like flows, a kind of dissipative structure. The transport rate V increased with the linear charge density of polyacrylic acid but became constant independent of the charge density if the latter exceeds a critical value. The counterion condensation was strongly suggested from this peculiar dependence on the charge density. The transport rate decreased with increasing NaCl concentration. At 0.5 M NaCl, the transport was no longer rapid but took place as a diffusion process. As another matrix–gradient system, transport of polyvinylpyrrolidone (PVP) through aqueous sodium polyacrylate solutions was also examined and rapid transport of PVP was found.