Preparing surface anion-imprinted material based on ion exchange and surface-initiated graft-polymerization and studies on its recognition character

Abstract

The molecularly imprinted polymers (MIPs) synthesized by conventional bulky imprinting methods suffer from several limitations, such as time-consuming preparation process, poor site accessibility to the target molecules and the lower binding capacity for the target molecules. To overcome these problems in bulking imprinting, in this work, a novel surface- ion imprinting method that not only is simple but also highly effective, is put forward and found. The coupling agent γ-aminopropyltrimethoxysilane (AMPS) was bond onto the surface of silica gel particles, and amino groups were introduced onto the surfaces of silica gel particles, obtaining the modified particles AMPS-SiO2. In aqueous solution, the molecules of the cationic monomer methacryloxyethyltrimethyl ammonium chloride (DMC) were first combined around the template ion, phosphate ion, by right of ion exchange action. A redox initiating system was constructed by the amino groups on AMPS-SiO2 and ammonium persulphate in the solution, and free radicals were produced on the surfaces of silica gel particles. These free radicals initiated the monomer DMC and the crosslinker N, N'-methylene bisacrylamide (MBA) to be graft-copolymerized and crosslinked, and the surface-imprinting of phosphate ion was realized. After removing the template ions, PO43-ion surface-imprinted material IIP-PDMC/SiO2 was obtained. Both permanganate ion, MnO4- ion, and PO43- ion are isoelectronic bodies. Their chemical structures are similar and their configurations are the same, but their sizes are different. In this work, MnO4- ion was used as contrast ion, and both static and dynamic methods were adopted to study the binding properties and ion recognition character of IIP-PDMC/SiO2 for PO43- ion. The experiment results show that IIP-PDMC/SiO2 have specific recognition selectivity and excellent binding affinity for PO43- ion, and its selectivity selectivity coefficients for PO43- ion with respect of MnO4- ion is 9.58. Besides, IIP-PDMC/SiO2 has excellent elution property, with NaCl solution as eluent, the desorption ratio of PO43- ion reach 99.53% in 20 BV. © 2012 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.