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Fixing the greenhouse gas CO2 through epoxide helps to mitigate worldwide ecological troubles. The applications of metal‐free and solvent‐free catalysts remain a challenge for CO2 catalytic conversion. In this work, an array of quaternary ammonium salts derived from polyethyleneimine with hydroxyl groups ([PEI‐GDMAB‐Cn]Br) were constructed by the reaction of branched PEI with a molecular weight of 10000 and glycidyl alkyl dimethylammonium bromide. A range of experiments were designed to demonstrate that [PEI‐GDMAB‐Cn]Br can be considered as a valid metal‐free and solvent‐free homogeneous catalyst for the CO2‐epoxide cycloaddition reaction. Among of [PEI‐GDMAB‐Cn]Br, [PEI‐GDMAB‐C18]Br catalyzed the model reaction of CO2 and epichlorohydrin under optimized reaction conditions (T=80 °C, 1.0 atm CO2, catalyst 1 mol%, ECH 15 mmol, 16 h) and the conversion achieved at 97.5 %. Moreover, the catalyst exhibited stable reusability and broad substrate applicability, which was used in the following cycle succinctly, because of self‐separated properties by temperature control. The [PEI‐GDMAB‐C18]Br catalyzed reaction process was detected as a pseudo‐first‐order reaction after kinetic studies and an Ea was calculated to be 50.65 kJ/mol. A combinatorial catalytic mechanism of hydrogen bonding and bromide ions is suggested to explain the remarkable catalytic performance of this bifunctional catalyst. [ABSTRACT FROM AUTHOR]

Carbon dioxide, as an industrial waste gas, has a severe impact on the climate. Thus, efficient catalytic conversion of CO 2 has attracted considerable attention worldwide. In this study, a series of crown ether-conjugated microporous polymer materials containing carboxylic groups (CCMPs) were synthesized through multi-components reactions in one pot. This synthesis involved the reaction of dialdehydebenzo-18-crown-6 with different monomers of amino and pyruvate in the presence of DDQ. Fourier transform infrared spectroscopy, carbon-13 cross-polarization magic angle spinning nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were used to characterize the CCMPs. Then, CCMPs were used in CO 2 fixation and iodine vapor adsorption. The co-catalyst KI and CCMP-4 exhibited excellent activity in mild conditions, resulting in a 94% yield. The catalytic activity of the CCMP-4 was maintained after the five cycles. The kinetics of CCMP-4 was studied, and a potential reaction mechanism was proposed. The iodine adsorption experiments were conducted on CCMPs. The results showed that CCMPs exhibited excellent adsorption effects at 75 °C. The adsorption capacities of CCMP-1, CCMP-2, CCMP-3 and CCMP-4 were 3.02, 2.68, 2.72 and 3.21 g·g−1, respectively. The experimental results showed that CCMPs effectively absorbed iodine vapor and exhibited an excellent catalytic effect on CO 2 cycloaddition under mild conditions, which is proved by density functional theory calculations further. [Display omitted] • The CCMPs possessed high catalytic efficiency for cyclic carbonate. • The adsorption experiment of iodine vapor was carried out to evaluate the adsorption effect of polymers. • The synergistic mechanism has been proved in terms of experimental results, dynamics and DFT calculation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SP-COPs exhibited high catalytic efficiency of CO 2 conversion and excellent I 2 adsorption capacity. • The synergistic mechanism of CO 2 conversion was proved by experimental and kinetics. • The iodine adsorption kinetic process was described. The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO 2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The E a was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics. [ABSTRACT FROM AUTHOR]