POLYMER-SUPPORTED REAGENTS - APPLICATION TO SEPARATION SCIENCE

The purpose of this review is to highlight new ligands that have been immobilized on polymers to form polymer-supported reagents which are s elective for the complexation of targeted metal ions from multicompone nt solutions. Polystyrene remains the most popular organic polymer sup port, and its synthesis by suspension polymerization yields beads with a diameter appropriate for large-scale applications. Immobilized liga nds include amines, pyridines, imidazoles, oximes, hydroxylamines, Sch iff bases, thiols, crown ethers, and a varity of phosphorus ligands. T he concepts inherent to reactive ion exchange, as first described by H elfferich, and the recently synthesized dual mechanism bifunctional po lymers can be used to build a unified theory of selectivity with polym er-supported reagents. The goal remains to engineer selectivity into p olymeric reagents in an a priori manner by understanding the basic pri nciples through which a polymeric reagent can recognize a targeted sub strate.