Post-modification of Gemini cross-linked poly(ionic liquid) stationary phase and the effect of...

Gemini cross-linked poly(ionic liquid) possess excellent stability and tunable structures, demonstrating significant application potential in the field of chromatographic separation. By introducing functional groups with different properties onto their backbones via post-modification, the separation selectivity of the stationary phases can be further precisely modulated. In this study, using a Gemini cross-linked poly(ionic liquid) as the fundamental backbone, two functionalized chromatographic stationary phases were prepared by post-modification with phenyl and pentafluorophenyl functional ligands, respectively, in order to investigate the separation differences between phenyl and pentafluorophenyl groups under various separation modes. The successful grafting of functional groups onto the prepared stationary phases was verified through multiple characterization methods, and the morphology and structure of the stationary phases were also characterized. The separation performance of the two modified stationary phases was evaluated by separating a variety of analytes under HILIC/IEC/RPLC modes. The results indicated that the introduction of phenyl and pentafluorophenyl groups imparted distinct separation selectivities to the stationary phases through different hydrophobic interactions, π-π interactions, and other synergistic effects; the pentafluorophenyl-modified stationary phase exhibited specific selectivity toward halogen-containing analytes based on the electronegativity and hydrophobicity of fluorine, whereas the phenyl-modified stationary phase performed better in separating compounds with different conjugated structures. This study provides a feasible strategy for modulating the separation selectivity of poly(ionic liquid) stationary phases via post-modification, and offers experimental evidence and theoretical support for the design and development of novel cross-linked poly(ionic liquid) stationary phases.