Review: Selective ligand-exchange adsorbents prepared by template polymerization

Abstract

Highly selective ligand‐exchange absorbents have been prepared by template polymerization, a process in which the target molecule serves as a template for assembly of specific recognition sites. In an effort to develop materials suitable for chromatographic separations, thin coatings of the selctive templated polymers have been grafted to two reactive macroporous supports, poly(trimethylolpropane trimethacrylate) (TRIM), and propylmethacrylate‐derivatized silica beads. The precursor polymer prepared from the trifunctioal TRIM monomer is macroporous and highly crosslinked, providing a stable structure for surface grafting. The TRIM precursor polymer and various surface‐grafted copolymers have been characterized by scanning electron microscopy (SEM) and IR, ^(13)C NMR, and XPS spectroscopic techniques. Composite adsorbents have also been prepared using propylmethacrylate‐modified silica particles. While equilibrium rebinding selectivites for both types of surface‐templated materials are similar to those reported previously for bulk‐polymerized template polymers, the composite materials are far better suited to chromatographic separations. Highly similar bis‐imidazole substrates can be separated by ligand‐exchange chromatography on these new templated adsorbents.

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