Abstract
The development of a nanoporous material from a columnar liquid crystalline complex between a polymerizable benzoic acid derivative and a 1,3,5‐tris(1H‐benzo[d]imidazol‐2‐yl)benzene template molecule is described. The morphology of the liquid crystalline complex is retained upon polymerization and quantitative removal of the template molecule affords a nanoporous material with the same lattice parameters. The nanoporous material selectively binds cations from aqueous solution, with selectivity for sodium and potassium ions over lithium and barium ions, as shown with FT‐IR. Binding is also quantified gravimetrically with a quartz crystal microbalance with dissipation monitoring, a technique that is used for this purpose for the first time here.
Highlights
The latter two papers (Kishikawa et al and Utilizing the nanosegregation of two covalently-connected, Lee et al.) used acrylate-functionalized benzoic acids to obtain a incompatible polymer blocks, nanoporous materials can be cross-linked matrix from which the template molecule could be obtained with pore diameters down to 10 nm after selective removed
The BTB molecule has a diameter of 1.6 nm (Figure S3, Supporting Information), and when this template molecule is removed from a polymerized benzoic acid matrix, formation of pores similar in size to the diameter of BTB can be expected
Comparison of the X-ray diffraction (XRD) diffraction patterns of the complex before and after polymerization of a bulk sample showed no change in the lattice parameters of the columnar hexagonal (Colhex) phase (Figure 3B)
Summary
An N H stretching vibration around 3200 cm−1 was absent in the complex, while a pronounced band arose in the complex at 3264 cm−1, typical for the formation of an imidazolium salt These changes confirmed that an acid–base reaction had taken place between the template (pKa of the protonated 2-phenylbenzimidazolium is 5.23) and the benzoic acid (pKa of gallic acid is 4.41).[29]. Upon annealing of the 3:1 complex in the isotropic state at 240 °C, phase separation of needle-shaped crystals was observed by POM (Figure S1, Supporting Information). Most likely these crystals consist of solid template or a 1:2 or 1:1 complex with benzoic acid 1. The BTB molecule has a diameter of 1.6 nm (Figure S3, Supporting Information), and when this template molecule is removed from a polymerized benzoic acid matrix, formation of pores similar in size to the diameter of BTB can be expected
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