## 4 Conclusions  
In this study, five stationary phases containing polymeric ionic liquids based on the AAIL **4** and variable amounts of DVB as the crosslinker were prepared, and their thermal stabilities and chromatographic properties for GC analysis were evaluated. The results obtained demonstrate that DVB is an excellent modulator of the properties of the resulting polymeric phases, and the degree of crosslinking represents a key parameter to define the overall chromatographic efficiency of the resulting silica-coated columns. In this study, the best results were obtained for a 20% crosslinking (DVB content, PIL20). The thermal stabilities observed for the cross-linked stationary phases were always higher than those for the stationary phase just containing the linear AAIL **4**-based PIL (PIL00). Moreover, the introduction of a crosslinker such as DVB was able to improve the separation properties, most likely due to the formation of a more homogeneous film along the capillary. However, the amount of crosslinker needs to be carefully adjusted. DVB amounts over 20% led to a loss of the dual behavior of the stationary phases most probably due to a reduction in the homogeneity of the polymeric phase with generation of separate domains (apolar/polar) and to a reduction in the accessibility to the analytes of the AAIL subunits through a reduction in mobility and diffusional properties.  
The solvation parameters calculated show that the dominant interactions are the hydrogen bond basicity (a-term) and the dipole interactions (s-term), with some contributions from the hydrogen  
Figure 4: Separation of Grob test: 1. decane, 2. undecane, 3. 2,3-butanediol, 4. 2-ethylhexanoic acid, 5. 1-octanol, 6. 2,6 dimethylphenol, 7. methyl decanoate, 8. dicyclohexylamine, 9. 2,6 dimethylaniline, 10. methyl undecanoate, 11. methyl laurate, 12. 1-nonanal. PIL-based stationary phases: **(a)** PIL00; **(b)** PIL10; **(c)** PIL20; **(d)** PIL30.  
bond acidity (b-term) and the dispersion forces (l-term), a trend that has also been observed for other imidazolium ILs. It must be noted that the l-term for the stationary phases based on the crosslinked PILs was greater than those for the linear polymeric coating exclusively based on the AAIL monomer (PIL00). This constant decreased with the increase in the amount of DVB. The highest values of the b term as compared with other commercial columns provides a significant potential for developing stationary phases with selectivities different from those currently available.  
Conceptualization, B.A. and J.G.-A.; methodology, S.V.L. and J.G.-A.; validation, B.A., J.G.-A. and S.V.L.; formal analysis, J.G.-A.; investigation, A.V., P.A.A., J.G.-R. and M.D.G.A.; resources, J.G.-A. and S.V.L.; data curation, B.A. and J.G.-A.; writing--original draft preparation, B.A., A.V. and J.G.-A.; writing--review and editing, S.V.L.; visualization, J.G.-A.; supervision, B.A., J.G.-A. and S.V.L.; project administration, S.V.L.; funding acquisition, S.V.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by MINISTERIO DE CIENCIA, INNOVACION Y UNIVERSIDADES, grant number RTI2018-098233-B-C22 and Pla de Promocio de la Investigacio de la Universitat Jaume I, grant UJI-B2019-40. A.V. work was funded by a MICINN within the predoctoral fellowship program, grant FPU15/01191.  
Technical support from the SECIC of the UJI is acknowledged.  
The authors declare no conflict of interest.