We have recently explored the use of high internal-phase emulsion (HIPE) foams as a chromatographic support for surface-grafted poly(4-vinyl pyridine) (P4VP) chains. P4VP is known to selectively chelate plutonium and iron ions which are targets for removal in nuclear aqueous waste streams. Current industrial practices rely on the use of functionalized, high surface-area resin beads to remove heavy metal ions. However, the large surface area of the resin is accessed primarily by diffusion, an inherently slow process. HIPE foams also have a high surface area available for solute sorption, but the fluid passes through the pores more freely, making convection the dominant mechanism by which mass transport occurs. This allows for easier, more efficient separations of target ions. Our research has directed us down two different pathways for the grafting method of P4VP chains, a photoinitated route and a thermally initiated route. Photoinitiation of the graft polymerization yields high MW of the P4VP grafted chains, but this method suffers from poor penetration depth of the light source into the opaque foam monoliths, making graft uniformity throughout the sample an issue. Another method which involves the attachment of a RAFT (or NMP) agent to the surface and subsequent polymerization yields uniform grafting, but the MW of the grafted chains is difficult to verify and the polymerization is seemingly slow. Preliminary results have shown that the grafted foams have the potential to significantly outperform the resin beads, and we are currently working on ways to optimize the performance and uniformity of columns prepared by photoinitated and thermally initiated surface functionalization.

Graft polymerization of P4VP on HIPE foams

251st National Meeting (2016)

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