Molecular Transport in Semidilute Macromolecular Solutions

Capillary zone electrophoresis and polymer dynamics

Capillary electrophoresis with a polymer solution support medium is a well-established powerful analytical tool. This paper discusses a possible alternative application of capillary electrophoresis, namely a path for studying the dynamics of polymer solutions. The key to the approach is an inversion of perspective. Instead of treating the migrating species as the object of experimental importance and the support medium as being of importance only because it facilitates separations, one treats the polymer solution as being of experimental importance, and the choice of migrating species as being of interest only because different species may probe different aspects of polymer dynamics.

Hydraulic conductivity of polymer matrices

We demonstrate that the chondroitin sulfate proteoglycan exhibits enhanced sensitivity to the flow of water compared to other macromolecules which is in accord with their functional role in conferring compressive resistance to cartilage. In order to understand factors that may contribute to its low hydraulic conductivity, a comparative study of hydraulic conductivity, as measured by the sedimentation velocity technique is made of various macromolecules representing variations in charge density, chemical composition, thermodynamic nonideality, size and flexibility. The polymers examined were dextran, poly(ethylene glycol), poly(vinyl alcohol), albumin, and dextran sulfate. The differences in hydraulic conductivity between the various macromolecules could not be explained by conventional theories which included prediction of hydraulic conductivity related to the radius of the molecule regarded as a uniform cylinder, nor the absolute charge density of the molecule and nor to the steric hindrance offered by the macromolecule to the diffusion of tritiated water. A qualitative relationship is established, however, between the noncounterion polymer contribution to osmotic activity and the resistance to water flow for polymers with high osmotic activity.