PERMEABILITY OF GRAFT-POLYMERIZED POLYVINYLPYRROLIDONE SILICA RESIN IN PACKED-COLUMNS

The effect of solvent power and flow rate on the permeability of a size exclusion chromatography (SEC) column packed with a novel polyvinylpyrrolidone (PVP)-grafted porous silica resin was studied. The PVP-silica resin was prepared from a porous silica size exclusion resin onto which a terminally anchored PVP layer was graft polymerized. The terminally anchored PVP layer was synthesized via a free radical graft polymerization method. The permeability of the PVP-grafted silica columns was determined from simple flow rate-pressure drop measurements. Qualitatively, as the solvent power increased, the permeability of the PVP-silica-packed column decreased. This behavior was consistent with the expected higher degree of swelling of PVP with increasing solvent power. The permeability was also lower for longer PVP surface-anchored chains. The change in the permeability of the PVP-grafted columns with shear stress was negligible, consistent with the estimate of a dense brush-like surface coverage by terminally anchored PVP molecules. The possibility of controlling the surface conformation of the PVP layer by changing the solvent power and possibly shear rate (for nonbrush coverage) suggests an additional degree of freedom in operating SEC columns. The use of polymer-silica matrix resins in size exclusion chromatography may be of special interest since one can tailor-design the surface by controlling the degrees of surface density and grafted polymer molecular weight. © 1992.