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Smart aqueous two-phase systems (ATPSs) were fabricated using ferrocenyl and benzyl-modified poly(ionic liquid)s for the first time. The novel ATPSs were found to be pH-sensitive. The upper phase and lower phase could be inverted reversibly by adjusting the pH value of the ATPSs. [ABSTRACT FROM AUTHOR]

Thermally induced reversible up/down migration of poly(ionic liquid)s (PILs) in aqueous two‐phase systems (ATPSs) was achieved for the first time in this study. Novel ATPSs were fabricated using azobenzene (Azo)‐ and benzyl (Bn)‐modified PILs, and their upper and lower phases could be easily tuned using the grafting degree (GD) of the Azo and Bn groups. Bn‐PIL with higher GDBn could go up into the upper phase and Azo‐PIL come down to the lower phase when the temperature increased (>65 °C); this behavior was reversed at lower temperatures. Moreover, a reversible two‐phase/single‐phase transition was realized under UV irradiation. Experimental and simulation results revealed that the difference in the hydration capacity between Bn‐PIL and Azo‐PIL accounted for their unique phase‐separation behavior. A versatile platform for fabricating ATPSs with tunable stimuli‐responsive behavior can be realized based on our findings, which can broaden their applications in the fields of smart separation systems and functional material development. [ABSTRACT FROM AUTHOR]

Functional porous organic polymers (POPs) have been extensively developed as heterogeneous catalysts for carbon dioxide conversion. However, exploring a general strategy to incorporate versatile active moieties into POPs is still a big challenge. In this study, a post-synthesis modification strategy was suggested for the fabrication of metalloporphyrin- and phosphonium-functionalized POPs. The as-prepared POP catalysts PPh2PStR-PMtVPP (R = C2–C12) were characterized by FT-IR, SEM, TEM, XPS, TGA, ICP, and TPD measurements. The results demonstrated that the PPh2PStR-PMtVPP catalysts were mesoporous and possessed a high adsorption capacity for CO2, which was advantageous for the cycloaddition reaction of CO2 and epoxides. Thanks to their rich Lewis acid sites and nucleophilic groups, PPh2PStR-PMtVPP could cooperatively activate substrates and achieve efficient synergistic catalysis for CO2 cycloaddition with epoxides. The effects of the phosphonium structure and different metal centers, as well as reaction conditions, on the catalytic performances of the functional POPs are discussed in detail. Under the optimized conditions, PPh2PStD-PCoVPP-1 could efficiently and selectively catalyze the coupling of CO2 and epoxides at 80 °C and 0.1 MPa CO2. Moreover, PPh2PStD-PCoVPP-1 could be easily separated and recycled five times without any obvious loss of catalytic activity. This study thus offers a powerful strategy for the fabrication of efficient bifunctional catalysts for CO2 conversion. [ABSTRACT FROM AUTHOR]

The development of efficient and metal-free heterogeneous catalysts for the chemical fixation of CO2 into value-added products is still a challenge. Herein, we reported two kinds of polar group (−COOH, −OH)-functionalized porous ionic polymers (PIPs) that were constructed from the corresponding phosphonium salt monomers (v-PBC and v-PBH) using a solvothermal radical polymerization method. The resulting PIPs (POP-PBC and POP-PBH) can be used as efficient bifunctional heterogeneous catalysts in the cycloaddition reaction of CO2 with epoxides under relatively low temperature, ambient pressure, and metal-free conditions without any additives. It was found that the catalytic activities of the POP-PBC and POP-PBH were comparable with the homogeneous catalysts of Me-PBC and PBH and were higher than that of the POP-PPh3-COOH that was synthesized through a post-modification method, indicating the importance of the high concentration catalytic active sites in the heterogeneous catalysts. Reaction under low CO2 concentration conditions showed that the activity of the POP-PBC (with a conversion of 53.8% and a selectivity of 99.0%) was higher than that of the POP-PBH (with a conversion of 32.3% and a selectivity of 99.0%), verifying the promoting effect of the polar group (−COOH group) in the porous framework. The POP-PBC can also be recycled at least five times without a significant loss of catalytic activity, indicating the high stability and robustness of the PIPs-based heterogeneous catalysts. [ABSTRACT FROM AUTHOR]