Polymeric Ionic Liquids as CO2 Selective Sorbent Coatings for Solid-Phase Microextraction

Two polymeric ionic liquids (PIL) were synthesized and employed as sorbent coatings in solid-phase microextraction (SPME) for the selective extraction Of CO2, ne two coatings, poly(1-vinyl-3-hexylimidazolium) bis[(trifluoromethyl)sulfonyl]imide [poly(VHIM-NTf2)] and poly(1-vinyl-3-hexylimidazolium) taurate [poly(VHIM-taurate)], exhibited varied selectivity toward CO2 due to functional groups within in the PIL that imparted different mechanisms of CO2 capture. Extraction efficiencies were compared to those of two commercial SPME fibers [poly(dimethylsiloxane) (PDMS) and Carboxen-PDMS]. ne poly(VHIM-NTf2) PIL fiber exhibited comparable extraction efficiency at high CO2 pressure compared to the Carboxen-PDMS fiber, even though the PIL-based fibers possessed much smaller film thicknesses. Calibration curves generated in pure CO2 showed that the sensitivity of the poly(VHIM-NTf2) coating was comparable to that of the Carboxen-PDMS fiber with both PIL-based fibers exhibiting larger linear ranges and higher extraction-to-extraction reproducibility. ne storage ability for selected fibers was examined kind revealed that the PIL-based coatings exhibited superior capability in retaining the CO, sorbate on the fiber under different storage conditions, particularly for the poly(VHIM-taurate) PIL which reversibly captures CO2 as a carbamate salt.