Imidazolium-based co-poly(ionic liquid) membranes for CO2/N2 separation

Unformatted post printThe development of efficient carbon dioxide capture and separation technologies is at the fore front of the priorities in the climate change policies. Poly(ionic liquid)s (PILs) have been emerging as extremely promising materials for the fabrication of membranes for CO2 separation. This work is a step forward to evaluate the performance of PIL-based copolymers in the preparation of membranes for CO2/N2 separation. In particular, imidazolium-based homo and copolymers were synthesized by RAFT co-polymerization of different imidazolium salts and characterized by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) analysis. The membrane forming ability of the synthesized PILs, as well as the influence of different side chain groups (ethyl, pentyl, benzyl and napthyl) at imidazolium ring, were evaluated using the solvent casting technique. In order to improve membrane forming ability and CO2 separation performance, different amounts of free ionic liquid (IL), [C2mim][NTf2], were added into the synthesized homo and copolymers, and PIL–IL composite membranes were prepared. The CO2 and N2 permeation properties of the obtained free standing PIL–IL membranes were measured at 20 ºC and 100 kPa and the results obtained compared through the Robeson plot.K. Vijayakrishna and N. Pothanagandhi thank “International Research Staff Exchange Scheme (IRSES) 7th Framework of European Union People-2012-IRSES” (Project No: 318873), for exchange programme. K. Vijayakrishna also thank DST-SERB, India (Project NO: SR/S1/OC-22/2012) for the financial support. L.C. Tomé is grateful to FCT (Fundação para a Ciência e a Tecnologia) for her Post-doctoral research grant (SFRH/BPD/101793/2014). This work was supported by FCT through the project PTDC/CTM-POL/2676/2014 and R&D units UID/Multi/04551/2013 (GreenIT) and UID/QUI/00100/2013 (CQE). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 745734

Layer-by-layer coated imidazolium – styrene copolymers fibers for improved headspace-solid phase microextraction analysis of aromatic compounds

The design of poly(ionic liquids) (PILs) and their application as solid phase microextraction (SPME) fibers has been attracting enormous attention mainly due to the need for new SPME coating materials with improved analytical sensitivity. In this work, the tunability of PILs is explored by preparing different imidazolium monomers bearing benzyl, naphtylmethyl or pentyl pending groups that were subsequently co-polymerized, by reversible addition–fragmentation chain transfer (RAFT) polymerization with styrene. The obtained co-polymers showed excellent thermal stability up to 275 °C, with no melting point up to 250 °C. SPME fibers were prepared by an innovative approach based on layer-by-layer spray coating. The thin (<10 μm) SPME coatings were tested in GC-FID for the detection of volatile aromatic compounds such as benzene (B), toluene (T), ethylbenzene (E) and xylene (X) present in aqueous samples and the extraction parameters optimized. Superior results were obtained when comparing these LbL PILS-based SPME fibers with a commercial fiber composed of poly(dimethylsiloxane), with an increase in the detectable areas of 83%, 69%, 57% and 58% for B, T, E and X, respectively. Low relative standard deviations were obtained for the same fiber (< 5.6%) and also for different fibers (< 9.8%). Furthermore, a spiked soil sample was used to mimic a real contaminated soil sample and excellent recovery results, ranging from 67.0% to 102.2%, were obtained.publishe

Step-growth Polymerization of Terephtaldehyde Catalyzed by N-Heterocyclic Carbenes

Benzoin condensation consists in reacting two aldehyde functions through a resonance-stabilized enaminol-type intermediate called the Breslow intermediate. This communication describes for the first time the use of N-heterocyclic carbenes (NHCs) as organic catalysts for the step-growth polymerization of a bis-aldehyde monomer, namely terephtaldehyde, which leads to poly(l,4-phenylene-l-oxo-2-hydroxyethylene) referred to as polybenzoin. These NHC-catalyzed polymerizations presumably involve the formation of Breslow intermediates. The effect of the NHCs catalyst activity and of the solvent polarity on the kinetics of the polymerization and on the formation of linear and cyclic polybenzoins is discussed

Extraction and coordination behavior of diphenyl hydrogen phosphine oxide towards actinides

<p>Extraction behavior of some selected actinides like U(VI), Th(IV), and Am(III) was investigated with three different H-phosphine oxides, <i>viz.</i> diphenyl hydrogen phosphine oxide (DPhPO), dihexyl hydrogen phosphine oxide (DHePO) and diphenyl phosphite (DPP). The H-phosphine oxides exhibited a dual nature towards the extraction of actinides where the ligand not only extracts the metals by cation exchange but also by coordination with the phosphoryl group at lower and higher acidic concentrations, respectively. Among all ligands employed, DPhPO showed highest extraction with actinides with a substituent dependent trend as follows: DPhPO > DHePO > DPP. This trend emphasizes the importance of substituents around the phosphine oxide towards their extraction of actinides. The coordination behavior of DPhPO was studied by investigating its corresponding complexes with Th(NO₃)₄ and UO₂(NO₃)₂. The metal complexes of these actinides were characterized using FT-IR, ¹H and ³¹P NMR spectroscopic techniques. Density Functional Theory (DFT) calculations were also performed to understand the electronic and geometric structure of the ligand and the corresponding metal complexes.</p