Ester exchange reaction of poly(N,N-diethylacrylamide-co-glycol methacrylate) with O,O-diethyldithiophosphate is shown to result in attachment of functional dithio phosphate group onto gels. The presence of N,N-diethylacrylamide moieties in the gels causes the gels to collapse when heated above the lower critical solution temperature, whereas ionization of the dithio groups at pH > 1.6 leads to drastic swelling. Selectivity of diethyldithio group toward metal ions enables gels to preferentially bind copper over zinc or calcium.