METAL-ION COMPLEXATION EQUILIBRIA OF ION-EXCHANGE RESINS PREPARED BY A SURFACE TEMPLATE POLYMERIZATION

A novel surface template polymerization technique has been proposed. Cu2+ ion-templated resin was prepared by use of oleic acid as host surfactant and divinylbenzene as matrix monomer. The resin showed characteristic Cu2+ complexation behavior when compared with non-templated resin results, i.e., Cu2+ ion adsorptivity of the templated resin was 10(3) times as high as that of non-templated resin in the low Cu2+ concentration region (p[Cu2+]-6 approximately 8). Since this high adsorptivity is expected to be closely related to a ''template effect'', various resins have been prepared under different preparation conditions, and their metal complexation equilibria were investigated potentiometrically. Several factors, such as the nature of initiator, water/oil ratio in emulsion, and the nature of the metal ions to be templated, strongly influenced metal complexation behavior of the prepared resins. The surface structure of the resin together with the flexibility of the hydrocarbon chain of the oleic acid incorporated in the resin are discussed in connection with the salt concentration dependence of the metal binding equilibria. Multidentate ligand complex formation seems to be a prerequisite for the ''template effect''.