Fluorinated covalent triazine frameworks for effective CH₄ separation and iodine vapor uptake

In this article, analogous covalent triazine framework (CTFs) were simply prepared through the trimerization of different nitrile building blocks (tetrafluoroterephthalonitrile or terephthalonitrile) under typical ionothermal conditions. We demonstrated that the fluorine contents could be simply altered by changing the comonomer compositions. Introducing fluorine could adjust the pore size distribution and electron structure of the network effectively. By increasing fluorine contents, an enhanced CO₂/CH₄ selectivity up to 15.5 was presented. Additionally, electron-concentrated fluorine strengthened CH/π interactions between the polymeric matrixes and guest CH₄, offering a CH₄/N₂ selectivity up to 8.0. The obtained CTFs also exhibited noticeable iodine adsorption capacity in vapor phase (302 wt%) due to their abundance of heteroatoms and porosity. These results clearly demonstrated the promising aspect of introducing fluorine groups into the porous networks for developing efficient sorbent towards potential applications in separating methane gas or iodine vapors and also affording further insight into the development of high performance functional polymers.