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

[Display omitted] •CTFs with different fluorine content were simply prepared through trimerization.•CTF-CSU43 displayed remarkable CH4/N2 selectivity up to 8.0.•CTFs exhibited CO2/CH4 selectivity up to 15.5.•CTFs showed high uptake capacity for iodine vapor up to 302 wt%. 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.