Ionic liquids (ILs) with aprotic heterocyclic anions (AHAs) are promising candidates for post-combustion carbon capture technologies since they react with CO2 stoichiometrically and reversibly. CO2 solubilities in two AHA-ILs, triethyl­(octyl)­phosphonium 2-cyanopyrrolide ([P2228]­[2CNPyr]) and triethyl­(octyl)­phosphonium benzimidazolide ([P2228]­[BnIm]), are reported for multiple temperatures and a third, triethyl­(octyl)­phosphonium 6-bromobenzimidazolide ([P2228]­[6-BrBnIm]), at one temperature. Ionic liquid [P2228]­[2CNPyr] and phase-change ionic liquid (PCIL) tetraethylphosphonium benzimidazolide ([P2222]­[BnIm]) were encapsulated in a chemically compatible and CO2-permeable polydimethylsiloxane (PDMS) polymer shell in order to enhance absorption and desorption kinetics. Both the free and encapsulated [P2228]­[2CNPyr] and [P2222]­[BnIm] were subjected to thermodynamic testing. The CO2 solubilities in the encapsulated IL and PCIL were in good agreement with the free IL and PCIL, meaning that the encapsulation of IL and PCIL greatly enhanced the kinetics of CO2 absorption while maintaining the high CO2 capture capacity. Recyclability testing was also performed on both the free and encapsulated [P2228]­[2CNPyr] and [P2222]­[BnIm]. The IL and PCIL materials, as well as the capsules, were stable upon cycling, with the CO2 capacities for each cycle remaining unchanged. The IL and the PCIL showed no sign of degradation after cycling, which demonstrated excellent performance.

The reaction between three aprotic heterocyclic anion (AHA) ionic liquids (ILs) (triethyl(octyl)phosphonium 2-cyanopyrrolide [P 2228 ]-[2CNPyr], triethylphosphonium benzimidazolide [P 2222 ][BnIm], and triethyl-(octyl)phosphonium indazolide [P 2228 ][Inda]) and CO 2 , in the presence of water, is investigated in this study. We propose a reaction mechanism where, in addition to the reaction of the anion with CO 2 to form carbamate, the anion reacts with water (i.e., hydronium ions in water from either the natural dissociation of water or the formation of carbonic acid) and is reprotonated, leaving CO 2 to react with hydroxide to form bicarbonate. This mechanism is confirmed for [P 2228 ][2CNPyr] and [P 2222 ][BnIm] by 1 H NMR, 13 C NMR, heteronuclear single quantum correlation NMR, and heteronuclear multiple bond correlation NMR, which were used to identify and quantify the reaction products. However, unlike the other two ILs, [P 2228 ][Inda] exhibits reprotonation of the anion when in contact with water only; i.e., CO 2 is not needed to form carbonic acid to increase the proton concentration in water. The reversibility of the reprotonation reaction was tested by measuring the CO 2 solubility in [P 2228 ][2CNPyr] and [P 2222 ][BnIm] in the presence of water for several cycles using a volumetric method. Previously, we have shown that the reaction of AHA ILs with CO 2 to form carbamate (in the absence of water) is reversible. Additionally, encapsulated [P 2228 ][2CNPyr] and [P 2222 ][BnIm]were subjected to a CO 2 solubility recyclability test in the presence of water. Both reactions between AHA ILs and CO 2 in the presence of water appear to be fully reversible. The encapsulated ILs showed good CO 2 capture capacity in the presence of water and good recyclability results, as well.

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Ternary hybrid interpenetrating networks composed of polyurethane (PU), poly(methyl methacrylate) (PMMA) and silica were prepared by in situ bulk polymerization. The inorganic phase was generated from tetraethoxysilane (TEOS) via sol‐gel chemistry. Highly transparent films were successfully synthesized using (trimethoxysilyl)propyl methacrylate (TMSPM) and isocyanatopropyl triethoxy silane (IPTES) as dual coupling agents. In order to minimize undesirable side‐reactions, PU was allowed to prepolymerize first before introduction of water into the reactive medium. According to infrared spectroscopic analysis and thermogravimetric studies of the hybrid materials, the condensation reaction was not complete certainly due to the presence of the organic components. The experimental procedure has to be optimized before any application of these hybrids as damping materials. Copyright © 2006 John Wiley & Sons, Ltd.