Post polymerisation hypercrosslinking of styrene/divinylbenzene poly(HIPE)s: Creating micropores within macroporous polymer

Porous copolymers of styrene and divinylbenzene (DVB) were prepared by emulsion templating using high internal phase emulsions (HIPEs) as precursors for monoliths. The ratio of monomers was varied in order to obtain samples with different degrees of crosslinking and different amounts of unreacted vinyl groups originating from DVB. PolyHIPE monoliths were subjected to reswelling and treatment with a radical initiator. Significant enlargement of the amount of meso- and micropores in the material was found resulting in a substantial increase of BET surface area, up to 7.2 times compared to untreated polyHIPEs. The treated PolyHIPE monoliths retained the open macroporous morphology typical of polyHIPE materials. Solid state 13C NMR experiments were used to determine the amount of unreacted vinyl groups in polyHIPE samples, both before and after the hypercrosslinking treatment.