Self-organization of a hydrophilic short-chain ionic liquid confined within a hydrophobic nanopore

Ionogel refers to the nanocomposite material composed of ionic liquid (IL) entrapped within the solid matrix. The performance of ionogel was predominantly dependent on whether the ILs within the pore of the matrix formed ordering or not. Thus far, such ordering information was largely provided via simulating the arrangement of ILs confined within nanopores with ordered geometry. However, experimental evidence was still lacking. Herein, we studied the ordering of a short-chain IL (1-butyl-3-methylimidazolium tertrafluoroborate) confined within the two distinct nanopores (radius-various H₂ pore and slit-shaped H₃ pore) of the methylated silica matrix with a fractal network by small-angle X-ray scattering. The results obviously indicated that these confined IL molecules indeed formed a self-organized ordering in the H ₃ nanopores, as is directly observed a correlation peak in the scattering patterns. We speculated on the plausible formation mechanism of this ordering in H₃ nanopores according to "the effects of broad pore sizes and rough surface topography on the pore wall".