| Abstract: | Dilute solutions of polystyrene in chloroform were filtered through track-etched mica membranes. The pores of each membrane were smaller than the mean unperturbed dimension of the polymer molecules. Three configurations of polystyrene were used: linear, comb-branched, and star-branched. The data for the linear polystyrenes show that the reflection coefficient σ decreases with solvent flow rate per pore q in a manner independent of molecular weight. At low flow rates the rejection is quantitatively described by 1 ? σ ～ q1.69. Comparisons among the three configurations show that as the extent of branching increases, σ increases at given solvent flow rate. It is concluded that filtration studies with well-defined porous membranes can provide a relative measure of deformability among various configurations of polymeric species. |
