Tunable and functional ionic liquids embedded hyper-crosslinked polymers as robust H2O-tolerant adsorbents for highly efficient gaseous toluene capture

A series of tunable and functional ionic liquids embedded hyper-crosslinked polymers (ILHCPs) containing different structures of anion-functional ionic liquids (ILs) with 1,4-dichloroxylene (DCX) as the crosslinker were designed and prepared for highly efficient gaseous toluene adsorption under humidity. These ILHCPs could achieve high surface area (600 ∼ 900 m² g⁻¹), high micropore volume (0.1 ∼ 0.3 cm³ g⁻¹), small average pore size (4 ∼ 5 nm), large water contact angle (up to 110°), and high thermal stability (>350 °C) through tuning the anion structures and the initial IL:DCX molar ratio. Gaseous toluene adsorption isotherms were well described by a dual-site Langmuir-Freundlich (DSLF) model, and the isosteric heats were calculated. The selectivity of gaseous toluene for 80 % humidity was calculated to be 0.26, two times of typical metal–organic frameworks MIL-101 (0.12), and it increase with the decrease of humidity. Compared with DCX-based self-condensed HCP, toluene adsorption capacity of ILHCPs remained steadily (270 mg g⁻¹) even under 80 % humidity. The results of experiments and quantum chemical calculations indicated that anion is the main reason for efficient toluene adsorption under high humidity. Moreover, after the pre-treatments (acid treatment, alkali treatment, adsorption 1 % H₂O, and adsorption 5 % H₂O), the robust ILHCPs showed a good chemical stability and a stable adsorption capacity. Adsorption-desorption reversible cycles without capacity decrease indicated the good repeatability of ILHCPs. To our best knowledge, this is the first example of tuning functional ILHCPs for efficient H₂O-tolerant gaseous toluene adsorption. The method may open a door to achieve efficient and robust IL-based materials