Abstract
A novel tetraphenylethylene-based ladder network (MP1) made by polycondensation reaction from 4,4',4″,4‴-(ethene-1,1,2,2-tetrayl)tetrakis(benzene-1,2-diol) and 2,3,5,6-tetrafluoroterephthalonitrile and its COOH-functionalized analogue (MP2) were synthesized for the first time. Their structures were confirmed by solid-state nuclear magnetic resonance (13C cross-polarization magic angle spinning), Fourier transform infrared spectroscopy, and elementary analysis. MP1 exhibited a high Brunauer-Emmett-Teller surface area (1020 m2 g-1), whereas the COOH-functionalized MP2 showed a much smaller surface area (150 m2 g-1) but displayed a more uniform pore size distribution. Because of the high density of nitrile groups in the network polymers of intrinsic microporosity (PIMs) and strong interaction with quadrupole CO2 molecules, MP1 exhibited a high CO2 adsorption capacity of 4.2 mmol g-1 at 273 K, combined with an isosteric heat of adsorption (Q st) of 29.6 kJ mol-1. The COOH-functionalized MP2 showed higher Q st of 34.2 kJ mol-1 coupled with a modest CO2 adsorption capacity of 2.2 mmol g-1. Both network PIMs displayed high theoretical ideal adsorbed solution theory CO2/N2 selectivities (51 and 94 at 273 K vs 34 and 84 at 298 K for MP1 and MP2, respectively). The high selectivities of MP1 and MP2 were confirmed by experimental column breakthrough experiments with CO2/N2 selectivity values of 23 and 45, respectively. Besides the promising CO2 capture and CO2/N2 selectivity properties, MP1 also demonstrated high sorption capacity for toxic volatile organic vapors. At 298 K and a relative pressure of 0.95, benzene and toluene sorption uptakes reached 765 and 1041 mg g-1, respectively. Moreover, MP1 also demonstrated some potential for adsorptive separation of xylene isomers with adsorptive selectivity of 1.75 for m-xylene/o-xylene.