We describe a new polymeric hydrogel that binds divalent metal ions with large binding constants and capacity. A new acrylate monomer with the pendant cyclen, tri-tert-butyl-10-(2-(2-(2-(methacryloyloxy)ethoxy)ethoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylate, was polymerised by RAFT to a roughly spherical 5–9 unit oligomer bearing a carboxylate-functionalised end-group. This was de-protected and coupled to an amine dendrimer then crosslinked into a nylon-type hydrogel capable of absorbing more than 10 wt% copper ions.