It is shown that pendant amino groups on polymers can be conveniently transferred into chemically and thermally very stable imidazolium linkages by using a simple modification of the Debus-Radziszewski synthesis, a cascade reaction involving two amines, one methylglyoxal and one formaldehyde monomer. It is shown that this reaction is so effective that it can be used either for the coupling of two terminal amino groups onto PEO chains or the high density x-linking of poly(L-lysine)s into poly(L-lysine)-imidazolium gels. In the latter case, it is shown that sterical hindrances restricts the conversion of amines to about 60 mol %, creating highly interlinked poly(L-lysine-imidazolate) microgels.