Benzimidazolium ionic liquid functionalized star-polycaprolactone stationary phase for capillary gas chromatography

In this work, an innovative ionic liquid functionalized star-shaped polymer is synthesized by coupling star-polycaprolactone with benzimidazolium (star-PCL-Bim), and statically coated into a capillary column for gas chromatographic (GC) separations. The fabricated star-PCL-Bim capillary column with moderate-polar nature reveals a high column efficiency of 3598 plates/m for n-dodecane at 120 degree celsius, and advantageous distinguishing ability (R > 1.5) for 9 aromatic isomer mixtures and 12 cis-/trans-isomers. Its excellent resolving capacity can be credited to the architecture of star-PCL-Bim, the PCL arms, and pi-electron-rich benzimidazolium cations, and it results in a quite different retention behavior of star-PCL-Bim from that of star-PCL and commercial HP-35 columns, with "dual-nature" selectivity in separating a mixture including 29 compounds. These favorable chromatographic characteristics demonstrate the great application potential of this material in GC, and provide a prospective strategy to obtain high-performance stationary phases.