The pellicular monolith: pore-surface functionalization and surface-phase construction in macroporous polymeric materials

We report synthesis and characterization of a macroporous polymeric materia l containing a covalently immobilized pore-surface phase of well-defined th ickness, gel-phase porosity and organic functional group content. The pore surfaces of otherwise inert macroporous (32 mu m mean pore size) ultrahigh- molecular-weight polyethylene (UHMWPE) are aminated throughout using a low- pressure flowing-discharge process to enable covalent immobilization of lig htly crosslinked polymer colloid particles on all pore surfaces in the mono lith. Solvent swelling and chemical derivitization of the covalently immobi lized polymer colloid particles produce a pore-surface gel phase of well-de fined thickness, organic amine content, and gel-phase porosity. The low deg ree of cross- linking in the polymer colloid particles prevents dissolution of the immobilized colloid in good solvents and enables the formation of p ore-surface gel phases having high gel porosity on swelling in good solvent s. The pore-surface amination introduced by the flowing discharge process v aries by less than 17% through 5-mm thickness of the macroporous UHMWPE mat erial. The properties of the pore-surface gel phase also vary by less than 17% through the cross section. The pore-surface immobilized polymer colloid particles swell by a factor of 10 in water and tetrahydrofuran after deriv itization with polyethylene glycol.