The present invention provides porous monoliths with high flow permeability that can be produced by polymerising and divinylbenzene in the presence of an initiator, a carboxy-functionalized nitroxide stable free radical and polymeric porogens. The monoliths produced with these stable free radicals functionalized with carboxylic groups feature porosities very different from those produced by polymerizations involving other SFRs, characterized by very large surface areas in combination with relatively large through-pores. The invention also provides a method for producing the monoliths, a column containing the monoliths and an assay method using the column.