Evaluation of proton conductivity of sulfonated polyimide/dihydroxy naphthalene charge‐transfer complex hybrid membranes

Sulfonated polyimide (SPI)/dihydroxynaphthalene (DHN) charge‐transfer (CT) complex hybrid films were investigated as possible alternative for polymer electrolyte membranes in polymer electrolyte fuel cells. SPI/DHN CT complex hybrid films include CT complexes, which might work as electronic conductors, and sulfonic acid units, which could work as proton conductors. Therefore, the origin of the conductivity of SPI/DHN complex hybrid films was evaluated by four‐probe impedance measurements in the through‐plane direction of the films. The obtained conductivity of the CT complex hybrid films increased with the increase of ion exchange capacity of the CT films and the decrease of CT complex concentration in the films. These results indicated that proton transfer dominantly occurred in the CT complex hybrid films. Proton conductivity of the CT complex hybrid films consisting of 2,6‐ or 1,5‐DHN showed the similar values, although the molecular geometries of the CT complex were different. The activation energy values for proton conductivity in the CT films were approximately the same as that of Nafion 212. Water uptake (WU) results were also conducted and suggest that CT complex formation could control the degree of WU of the films and prevent dissolution of SPI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2991–2997     

Development of an immunosensor for the detection of Francisella tularensis antibodies

Tularemia, also known as rabbit fever, is a highly infectious zoonotic disease caused by a non-motile and non-spore-forming Gram-negative coccoid rod bacterium, Francisella tularensis. It occurs naturally in lagomorphs (rabbits and hares), but many animals have been reported to be susceptible. Transmission to humans is mostly caused by inhalation of aerosolised bacteria, handling of infected animals, arthropod stings, and ingestion of contaminated foods and water. At present, pathogenic isolation, molecular detection, and serology are the most commonly used methods to confirm the diagnosis of tularemia. In this work, an electrochemical immunosensor for the detection of anti-F. tularensis antibodies was developed, consisting of gold-based self-assembled monolayers of a carboxylic-group-terminated bipodal alkanethiol that is covalently linked to a lipopolysaccharide (LPS) that can be found in the outer membrane of the bacteria F. tularensis. The presence of anti-F. tularensis antibodies was measured using horseradish peroxidase-labelled protein A (HRP-protein A) from Staphylococcus aureus, and the developed immunosensor gave a stable quantitative response to different anti-F. tularensis FB11 antibody concentrations after 30 min with a limit of detection of 15 ng/mL, RSD of 9 %, n?=?3. The developed immunosensor was tested with serum from animals infected with tularemia and was compared to the results obtained using ELISA showing an excellent degree of correlation.     

Hybrid films of polyetherimide containing in situ grown Ag,Pd, and AgPd alloy nanoparticles: Synthesis route,morphology, and gas transport properties

In this study, bimetallic/polymer films are synthesized from polyetherimide (PEI), palladium acetate and silver nitrate for a wide range of total metal amount (from 0 to 30 wt %) and different Ag to Pd molar ratios. Hybrid precursor films are first prepared from polymer/metal complex solutions and the metal nanoparticles are then generated within the PEI matrix by annealing the precursor film under specific conditions. Reference neat PEI films and monometallic films are prepared in the same conditions. Interestingly, formation of AgPd alloys directly within the polymer films is for the first time obtained from a very simple and environmentally friendly route. Based on X‐ray diffraction and transmission electron microscopy analyses, a nanostructuration mechanism is proposed. The interactions of hydrogen towards the nanocomposites are investigated and discussed as a function of the nanoparticle composition. The impact of the nanostructuration is also studied on H₂, CO₂, and He permeation properties. Significant improvement of barrier properties is achieved. The pertinent parameters of the gas transport are identified and modelled for each gas/composite system. Finally, from both morphological and gas transport analyses, it is concluded that in situ generation AgPd alloys with Pd to Ag ratio above 1 leads to very interesting and promising materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1211–1220     

Polymer‐Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal–Organic Frameworks

A template‐assisted polymer‐derived ceramic route is investigated for preparing a series of silicoboron carbonitride (Si/B/C/N) foams with a hierarchical pore size distribution and tailorable interconnected porosity. A boron‐modified polycarbosilazane was selected to impregnate monolithic silica and carbonaceous templates and form after pyrolysis and template removal Si/B/C/N foams. By changing the hard template nature and controlling the quantity of polymer to be impregnated, controlled micropore/macropore distributions with mesoscopic cell windows are generated. Specific surface areas from 29 to 239 m² g^?1 and porosities from 51 to 77 % are achieved. These foams combine a low density with a thermal insulation and a relatively good thermostructural stability. Their particular structure allowed the in situ growth of metal–organic frameworks (MOFs) directly within the open‐cell structure. MOFs offered a microporosity feature to the resulting Si/B/C/N@MOF composite foams that allowed increasing the specific surface area to provide CO₂ uptake of 2.2 %.     

Tris(3,5‐dimethylpyrazolyl)methane‐Based Heterobimetallic Complexes that Contain Zn and CdTransition‐Metal Bonds: Synthesis,Structures, and Quantum Chemical Calculations

Reactions of the tris(3,5‐dimethylpyrazolyl)methanide amido complexes [M′{C(3,5‐Me₂pz)₃}{N(SiMe₃)₂}] (M′=Mg ( 1 a ), Zn ( 1 b ), Cd ( 1 c ); 3,5‐Me₂pz=3,5‐dimethylpyrazolyl) with two equivalents of the acidic Group 6 cyclopentadienyl (Cp) tricarbonyl hydrides [MCp(CO)₃H] (M=Cr ( 2 a ), Mo ( 2 b )) gave different types of heterobimetallic complex. In each case, two reactions took place, namely the conversion of the tris(3,5‐dimethylpyrazolyl)methanide ligand (Tpmd*) into the ‐methane derivative (Tpm*) and the reaction of the acidic hydride M?H bond with the M′?N(SiMe₃)₂ moiety. The latter produces HN(SiMe₃)₂ as a byproduct. The Group 2 representatives [Mg(Tpm*){MCp(CO)₃}₂(thf)] ( 3 a / b ) form isocarbonyl bridges between the magnesium and chromium/molybdenum centres, whereas direct metal–metal bonds are formed in the case of the ions [Zn(Tpm*){MCp(CO)₃}]⁺ ( 4 a / b ; [MCp(CO)₃]^? as the counteranion) and [Cd(Tpm*){MCp(CO)₃}(thf)]⁺ ( 5 a / b ; [Cd{MCp(CO)₃}₃]^? as the counteranion). Complexes 4 a and 5 a / b are the first complexes that contain Zn?Cr, Cd?Cr, and Cd?Mo bonds (bond lengths 251.6, 269.8, and 278.9 pm, respectively). Quantum chemical calculations on 4 a / b* (and also on 5 a / b* ) provide evidence for an interaction between the metal atoms.     

Polyimide polydimethylsiloxane triblock copolymers for thin film composite gas separation membranes

This article demonstrates the successful fabrication of thin‐film‐composite (TFC) membranes containing well‐defined soft‐hard‐soft triblock copolymers. Based on “hard” polyimide (PI) and “soft” polydimethylsiloxane (PDMS), these triblock copolymers (PDMS‐b‐PI‐b‐PDMS), were prepared via condensation polymerization, and end‐group allylic functionalization to prepare the polyimide component and subsequent “click” coupling with the soft azido functionalized PDMS component. The selective layer consisted of pure PDMS‐b‐PI‐b‐PDMS copolymers which were cast onto a precast crosslinked‐PDMS gutter layer which in turn was cast onto a porous polyacrylonitrile coated substrate. The TFC membranes' gas transport properties, primarily for the separation of carbon dioxide (CO₂) from nitrogen (N₂), were determined at 35 °C and at a feed pressure of 2 atm. The TFC membranes showed improvements in gas permselectivity with increasing PDMS weight fraction. These results demonstrate the ability for glassy, hard polymer components to be coated onto otherwise incompatible surfaces of highly permeable soft TFC substrates through covalent coupling. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3372–3382