Metal ion-small molecule complex imprinted polymer membranes: Preparation and separation characteristics

A zinc(II)-(2,2′-bipyridyl) complex imprinted membrane with a PVDF membrane as a supporting material was prepared by ionic imprinting technology. In the first step, Zn(II) established a coordination linkage with 2,2′-bipyridyl and functional monomer (4-vinylpyridine). Next, the complex was copolymerized with ethylene glycol dimethacrylate (crosslinker) in the presence of the initiator, 2,2′-azobisisobutyronitrile. The surface features of the membranes were analyzed using scanning electron micrograph and infrared spectra. The structure of the blank membrane showed obvious changes after the polymerization reaction. A layer of polymer was formed on or in the supporting material. In experiments exploring the adsorption and permeation binding characteristics of the target molecule, the imprinted polymer membranes exhibited selective adsorption or permeation for the imprinted zinc ion. The relative selective factor (α′) of the imprinted membrane for the target ion was 2.12, which was greater than that of the control membrane (1.34) due to the dual functions of the imprinting and mediation of small molecules. This paper also discussed the adsorption and permeation mechanism of the membranes in detail.