Fabrication of Hydrophobic Hyper-Cross-Linked PolymersAs Excellent VOC Adsorbents

Using a one-pot method, the methylfluoroketone derivatives hexafluoroacetone (HFA) or 2,2′,2″-trifluoro-1-phenylethanone (TFPA) were doped into porous hyper-cross-linked polymers prepared by oxidative coupling of 9,9′-spirobi[9H fluorescence] (SF) or truxene (Tru), creating a family of hydrophobic porous hyper-cross-linked polymers (HCPs), namely <b>SF-HFA</b>, <b>SF-TFPA</b>, <b>Tru-HFA</b>, and <b>Tru-TFPA</b>, which has been presented in this work. Their structures were determined by FT-IR, solid-state ¹³C NMR spectroscopic techniques, and X-ray photoelectron spectroscopy (XPS). The four HCPs exhibit high specific surface areas above 800 m²/g and a rich distribution of micropores with pore sizes less than 1 nm. Moreover, they exhibit high hydrophobicity with contact angles exceeding 120°. The breakthrough adsorption experiments revealed that the four HCPs exhibited excellent adsorption capacity for toluene, ethyl acetate, <i>n</i>-hexane, and cyclohexane. Specifically, <b>SF-HFA</b> and <b>Tru-HFA</b> exhibited significant saturated adsorption capacities of 624 and 709 mg/g for toluene, respectively. The adsorption behaviors can be fitted by the Boltzmann model and the Yoon–Nelson model, indicating low mass transfer resistance and high adsorption rate in the fixed bed. The adsorption rate is controlled by both external diffusion and intraparticle diffusion, as shown by the intraparticle diffusion model analysis. The adsorption capacity of toluene on <b>Tru-HFA</b> remains virtually unchanged even under high humidity conditions (70%) or undergoing three heat desorption cycles, demonstrating exceptional water and heat resistance. Overall, these assets suggest the use of the hydrophobic porous HCPs, prepared by a simple method, as viable materials for reducing VOC emissions from industrial processes.