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Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems. [ABSTRACT FROM AUTHOR]

Abstract: A series of sulfonated poly(fluorenyl ether nitrile oxynaphthalate) (SPFENO) copolymers with different degree of sulfonation (DS) are synthesized via nucleophilic polycondensation reactions with commercially available monomers. Incorporation of the naphthalanesulfonate group into the copolymers and their copolymer structures are confirmed by 1H NMR spectroscopy. Thermal stability, mechanical properties, water uptake, swelling behavior, proton conductivity and methanol permeability of the SPFENO membranes are investigated with respect to their structures. The electrochemical performance of a direct methanol fuel cell (DMFC) assembled with the SPFENO membrane was evaluated and compared to a DMFC with a Nafion 117 membrane. The DMFC assembled with the SPFENO membrane of proper DS exhibits better electrochemical performance compared to the Nafion 117-based cell. [Copyright &y& Elsevier]

Abstract: Nafion composite membranes for CO2 separation with good CO2/CH4 separation factors were developed using ionic liquids (ILs) and Nafion. Three ionic liquids containing the 1-n-hexyl-3-methylimidazolium ([hmim]) cation with different anions were characterized by the measurement of the CO2 separation performance using supported ionic liquid membranes in a polysulfone asymmetric support. Two different Nafion membrane-containing ILs for CO2 separation membranes were prepared by the adsorption of IL on a dense and electrospun Nafion/polyethyleneoxide composite membrane in order to improve the stability of the liquid membrane. The electrospun Nafion layer containing polyethyleneoxide was prepared by the electrospinning technique in order to affix [hmim][BF4] (or [hmim][PF6]) on the porous polysulfone asymmetric support. The ideal CO2/CH4 separation factor of electrospun Nafion composite membranes with [hmim][BF4] was consistent with that of [hmim][BF4]. The ideal CO2/CH4 separation factor was 26 for the Nafion composite membranes containing both [hmim][BF4] and [hmim][PF6] in the dense Nafion layer, implying a change in the microdomain of Nafion in the presence of IL and the facilitation effect of ILs for CO2 separation through the IL-swollen Nafion membrane. [Copyright &y& Elsevier]

Abstract: Consolidants based on tetraethoxysilane (TEOS) have been widely used for the consolidation of decaying stone heritages. These products polymerize within the porous structure of the decaying stone, significantly increasing the cohesion of the material. However, TEOS-based consolidants suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force, which is typical for TEOS-based consolidants. We have prepared new consolidants TEOS-based consolidants containing flexible (3-glycidoxypropyl) trimethoxysilane (GPTMS) and silica nanoparticles in order to reduce capillary force development during gel drying, and have characterized them for the application of stone consolidants. Different sizes of silica nanoparticles were used, which were smaller than the pore size of the tested stone. The properties of the TEOS/GPTMS/nanoparticle composite solution were compared with those of the commercial products Wacker OH and Unil sandsteinfestiger OH 1:1. The gelation time was similar to that of commercial consolidants, and the TEOS/GPTMS/nanoparticle solution was stable over a period of up to six months. The contact angle of the surface increased with the addition of the nanoparticle, as well as with the addition the GPTMS, which is higher than that of commercial Wacker OH. The addition of a nanoparticle, as well as GPTMS having flexible segment, provided a crack-free material, while the gels obtained from the commercial consolidants exhibited cracking. [Copyright &y& Elsevier]

Abstract: Organic–inorganic hybrid electrolyte membranes were prepared with a sol–gel reaction of 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethoxysilane (TEOS) in the presence of different amounts of deoxyribonucleic acid (DNA), and compared with DNA/poly(ethylene imine) (PEI) and DNA/poly(ethylene oxide) (PEO) blend membranes with the aim of understanding the matrix effect on the electrolyte membrane properties. DNA, comprising of phosphates along a rod-like polymer of heteroatomic rings, was used as a facilitate proton transport channel in electrolyte membranes under low humidity conditions and was dispersed inside of the inorganic matrix created with the TEOS/GPTMS solution, which produced an amorphous electrolyte membrane. The proton conductivity of the DNA/TEOS/GPTMS electrolyte membranes increased with DNA loading and temperature. The proton conductivity of 30wt% of DNA in an amorphous inorganic matrix at 120°C under an N2 environment was measured at 4.9×10−4 S/cm, which is an order of magnitude higher than that of DNA in a crystalline PEO matrix and is lower than that in a more basic PEI matrix. This result implies that the main requirements for high proton transport under low humidity are the homogeneity of the membrane along with the dissociation of the proton from its ionic sites in the matrix. [Copyright &y& Elsevier]

Abstract: Cast Nafion and sulfonated poly[styrene-b-(ethylene-r-butylene)-b-styrene] copolymer (sSEBS)-based composite membranes containing different amounts of organic nanorod-shaped polyrotaxane (PR) were prepared and characterized, with the aim of improving the methanol barrier property of polymer electrolyte membranes (PEMs) for application in direct methanol fuel cells (DMFCs). PR was prepared using the inclusion complex reaction between α-cyclodextrin (α-CD) and poly(ethylene glycol) (PEG) of different molecular weights. The addition of PR to the structure of sSEBS, which involves hexagonal packing of cylinders, reduces the proton conductivity, as well as the methanol permeability, implying the creation of a tortuous path for methanol. The addition of PR to Nafion with ionic clusters reduced the crystallinity. The conductivity of the Nafion composite membranes increased on PR addition and decreased at higher PR contents. The organic PR inside the membrane changed the morphology during membrane preparation and provided a tortuous path for the transport of methanol. All of the sSEBS- and Nafion-based PR composite membranes showed higher selectivity parameter. [Copyright &y& Elsevier]

Abstract: Liquid phase isoprene/n-pentane mixtures can be separated through the use of facilitated transport membranes containing complexes of silver ions with an ionic liquid (IL). 1-Butyl-3-methyl imidazolium tetrafluoroborate and zwitterion-type imidazolium compounds containing covalently-bound sulfonate groups form complexes with AgX (X=BF4, NO3, and ClO4). Facilitated isoprene transport has been observed with selectivities that depend on the counteranion of the silver salt. The facilitated transport phenomena of the olefin and IL/silver complexes were investigated theoretically by calculating their complexation energies (i.e., the energy of formation of the silver complexes with the olefin) with the density functional theory method. Among polymer/silver salt systems, the polymer/AgBF4 system has been found to be generally more favorable for facilitated olefin transport than the polymer/AgNO3 system because of the low lattice energy of AgBF4. However, there is a different trend for IL/AgX systems. This difference may arise because the positively charged components of the IL can interact with the anions of the silver salt, which changes the olefin complexation activity. For IL/AgX systems, the selectivity varies inversely with the complexation energy, which implies that the diffusion of the carrier may be the significant factor affecting isoprene/n-pentane separation, once the appropriate complexation has occurred between olefin molecules and the ILsilver complexes. [Copyright &y& Elsevier]

Abstract: Conductive, self-assembled DNA composite membranes supported by a nano-porous polycarbonate substrate were fabricated. The porous polycarbonate support membranes were modified with Sn2+ positive charges to induce effective DNA adsorption. Optimum pore size of 0.1μm and high pore density have been realized for track etched nano-porous polycarbonate membrane in the self-assembly process. Proton conductivity and methanol permeability (10wt.%) were evaluated to be 8.0×10-2S/cm and 5.0×10-7cm2/s for 1.6mg/cm2 of DNA loading, respectively. The self-assembled DNA composite membranes exhibit excellent proton conductivity, and enhanced mechanical properties with decreased methanol permeability. [Copyright &y& Elsevier]

Remarkably high-performance membranes are developed by physically dispersing silver ionic aggregates in inert polymer such as poly(dimethyl siloxane) (PDMS). The mixed gas selectivity for propylene/propane reaches nearly 200, to our knowledge the highest value ever reported for the solid state, whereas other membranes reported up to now show ∼60 of propylene/propane selectivity. Physical dispersion of silver salt in the inert polymers without specific interaction is observed by FT-IR, FT-Raman and wide angle X-ray scattering (WAXS). It is also found that the crystalline silver ionic aggregates are completely dissolved under the propylene environment, representing that propylene is a good ligand for coordination to silver ions. The inert membranes are functional at any loading level and hence a threshold carrier concentration does not exist. [Copyright &y& Elsevier]

Recently, researches about polymer electrolytes have been spotlighted owing to their potential applications in polymer batteries, fuel cells and solar cells. To our knowledge, no report has been published on polymer electrolytes by π-complexation between transition metal ion and olefinic ligand of a polymer matrix although several have been reported by the coordination between metal ion and nonbonding electrons of oxygen, nitrogen, etc. In this communication, we report that polymer electrolytes consisting of silver salt and polymer containing C&z.dbnd6;C bond are developed and especially applied to the facilitated olefin transport membranes for the separation of olefin/paraffin mixtures. [Copyright &y& Elsevier]

Polymer electrolytes containing silver salts have gained great interest due to their effective performance in the separation of olefin/paraffin mixtures. However, they suffer from the poor long-term stability. The membrane performance of polyvinylpyrrolidone (PVP)/AgBF4 membranes was decreased with time primarily due to the reduction of silver ions to silver metal. In this study, non-ionic n-octyl β-d-glucopyranoside (8G1) surfactant has been employed to prolong the stability of the separation performance of PVP/AgBF4 membranes. It was found that the growth rate of the silver particles became slower and the propylene permeability was maintained for much longer time when 8G1 was added into the membranes. The reduction behavior of silver ions to silver metal particles and their growth were investigated by Transmission electron microscopy (TEM), scanning electron microscope (SEM), and UV spectroscopy. [Copyright &y& Elsevier]

Structural characteristics and membrane performance of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (sSEBS) copolymer proton exchange membranes in water-swollen and different ratio of water/methanol-swollen are studied by small angle X-ray scattering (SAXS), ATR FT-IR, AFM. SAXS profile of sSEBS membrane showed that microstructure was a hexagonally cylindrical structure and it was maintained in the existence of methanol in water until 30 wt.%. As the main interest was on the development of proton exchange membranes for fuel cells operating at lower temperature with liquid methanol feed, a selective thin layer was introduced on the top of sSEBS membrane by simple plasma treatment in the presence of maleic anhydride in order to prevent methanol crossover. Both methanol permeability and proton conductivity gradually decreased with increasing loading amounts of maleic anhydride. Hydrophobic anhydride properties on the top of sSEBS membrane act as a barrier for methanol but also for proton, resulting in decreasing methanol permeability and proton conductivity. The hydrolysis of anhydride groups to carboxylic acid provides a facilitated transport site for the proton. After hydrolysis, the proton conductivity was recovered and the recovery rate of proton conductivity by hydrolysis was higher than that of methanol permeability. [Copyright &y& Elsevier]

Nanoporous composite membranes coated on the microporous support with a ladder-like ionic polymer were prepared and the structural selectivity effect of the membrane on a non-aqueous vanadium redox flow battery (RFB) was investigated. Crosslinkable ladder-like ionic polysilsesquioxane (L-PSQ) was synthesized and a Celgard 2400 membrane was used for the support. An L-PSQ/Celgard composite membrane was prepared by the thermal crosslinking reaction of crosslinkable L-PSQ after the dip-coating process. The permeability of ionic L-PSQ/Celgard composite membranes decreased by two orders of magnitude upon thin coating while maintaining its high ion conductivity of the porous support, which provides higher charge/discharge capacity and cell efficiencies of RFB at all current densities compared to those of the RFB with the porous Celgard 2400 membrane. Due to the reduction of the crossover, the coulombic and energy efficiencies of non-aqueous vanadium RFB increase and reached 62.7% and 43.7%, respectively, for the RFB with the membrane containing 5.4 wt% of L-PSQ. These values are higher than those obtained for the Celgard membrane and the commercial Neosepta AHA membrane. This result implies that structure control of the membrane is a practical solution for the adaptation of the non-aqueous RFB for the future energy storage systems. • The structural permselective effects of the membranes used in non-aqueous redox flow batteries (RFBs) was studied. • Nanoporous composite membranes were prepared with crosslinkable ladder-like ionic polysilsesquioxane. • A selectivity parameter was defined for evaluating the membranes in RFB. • A non-aqueous RFB with a nanoporous composite membrane shows higher efficiency than that with a commercial membrane. • Controlled pores in the ladder-like ionic polymer layer on a porous membrane enable successful RFB application. [ABSTRACT FROM AUTHOR]

In this study, two different structured poly(diallyldimethylammonium chloride) (PDDA)/urushi composite membranes on porous supports were prepared, and their effects on the efficiency of non-aqueous Fe-Ni redox flow batteries (RFBs) were investigated. Chemically/mechanically stable urushi, which was thermally polymerized from urushiol, was chosen as the matrix, and PDDA was used as the anion-exchange material. A thin-layered composite membrane was fabricated by coating a PDDA/urushiol solution on top of the porous support. Moreover, a charged-porous structure was prepared by the penetration of a DDA/urushiol solution into the pores of the porous support, followed by thermal polymerization. The composite membranes exhibited reduced permeabilities; however, their ion conductivities were of the same order as that of the commercial FAP450 membrane. The coulombic efficiency (CE) and energy efficiency (EE) of the RFBs with charged-porous composite membranes were 90.7% and 76.2%, respectively; the CE and EE values were 79.0% and 68.7% for the non-aqueous Fe-Ni RFBs with thin-layered composite membranes, at a current density of 0.5 mA cm –2 , which are higher than those obtained with a commercial FAP450 membrane. These results indicate that controlled porosity in an anion-exchange material on a chemically and dimensionally stable porous membrane contribute to the successful application of RFBs in energy storage systems. [ABSTRACT FROM AUTHOR]

Abstract: It is well known that the reduction of AgBF4 to silver nanoparticles inevitably occurs over time even under dark conditions. In particular, the reduction rate of AgBF4 in a polymer/silver salt complex is much faster than for any other silver salt. However, when Al(NO3)3 was incorporated into a POZ/AgBF4 complex, the reduction of silver ion was suppressed for more than 14 days. Stable silver ions were confirmed by the separation performance of propylene/propane mixtures over time and by the color change of the POZ/AgBF4/Al(NO3)3 complex. FT-IR and FT-Raman spectroscopy showed that ionic aggregation between the silver ion of AgBF4 and NO3 - of Al(NO3)3 occurred, which was much stronger in intensity than interactions in the POZ/Al(NO3)3 and POZ/AgNO3 complexes. This strong aggregation behavior was attributable to a favorable interaction between F− of AgBF4 and Al3+ of Al(NO3)3, resulting in a weakened interaction between Al3+ and its counteranions, which was confirmed by XPS. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cells (DSSCs) with quasi-solid ion-gel electrolytes are fabricated using a 1-propyl-3-methyl imidazolium iodide (PMII) with a small amount of poly(styrene-block-ethyleneoxide-block-styrene) (SEOS) triblock copolymer. The interaction between the PMII and SEOS changes the liquid state of PMII into a solid state, and the interactions between the imidazolium cation of PMII and the ethyleneoxide of SEOS are confirmed by an ab initio method. The phase change of the electrolyte from an ionic liquid to a quasi-solid ion-gel in a DSSC slightly increases the photoconversion efficiency, and the DSSC containing an ion-gel maintains 92% of its efficiency under more than 1440h of operation, which is higher than that with the ionic liquid as an electrolyte (78%) in this system. The addition of dendrons as a barrier-forming co-adsorbent increases the short-circuit current density (J sc) of the DSSC. Up to a 27% increase in the power conversion efficiency are achieved with the G5 dendron as the co-adsorbent. EIS and IPCE measurements show that the increase in J sc is due to the suppression of recombination by the surface coverage of the TiO2 particles. The photocurrent and the conversion efficiency for all DSSCs prepared with quasi-solid ion-gel electrolytes and dendron co-adsorbents are higher than those prepared with an ionic liquid. [Copyright &y& Elsevier]

Abstract: Homogeneous acid-doped polysiloxane (PS) electrolyte membranes were prepared by the sol–gel reaction from 3-aminopropyltriethoxysilane (APTES) and different acids, such as sulfuric acid (SA), methanesulfonic acid (MSA), ethanesulfonic acid (ESA), and 1-propanesulfonic acid (PSA). The effect of the acidity as well as the structure on the proton transport has been investigated. The interaction between the acid and the basic nitrogen of PS made by APTES has been confirmed by FT-IR and ab initio calculation. The thermal stability depends on the stability of the doping acid. The structure of acid-doped PS was determined by X-ray diffraction pattern and changed with the kind of acid as well as the doping amount. The proton conductivity of annealed (1:1) PS/SA membrane having high acidity as well as the hexagonal-like structure reached 1.1×10−3 S/cm at 120°C under no (or low) humidity, which is more than one order of magnitude higher than those of PS/acid membranes without structure. The structural effect was studied by PS/ESA membrane having different structure with the amount of acid doping. The proton conductivity of (3:1) PS/ESA membrane showing hexagonal-like structure is 3.82×10−4 S/cm, whereas it is 9.6×10−6 S/cm at 120°C for amorphous (1:1) PS/ESA membrane. This result implies that the main requirements for high proton transport of electrolyte membranes prepared by acid–base interaction under low humidity are the acidity and the proton transport structure. If the acidity is fixed, then the presence of the ionic channel structure is essential to design the electrolyte membrane having high proton conductivity. [Copyright &y& Elsevier]

Abstract: DNA, comprising phosphate ions along a rod-like polymer of heteroatomic rings, was used as the proton transport channel in polymer electrolyte membranes under conditions of high temperature and low humidity. Cast DNA/poly(ethylene oxide) (PEO) blend membranes containing different amounts of DNA were prepared and characterized. Two different molecular weights of PEO were used to provide mechanical strength. The proton conductivity of DNA/PEO membranes increased with the DNA loading and the temperature. The crystallinity of PEO decreased with increasing amounts of DNA, which would improve interaction between the basic oxygen of PEO and the acidic hydrogen of DNA. This would enhance the dissociation of hydrogen from DNA phosphate groups, resulting in increased proton conductivity. The DNA/PEO complexes were investigated in terms of their complexation energy using density functional theory and the effect of hydrogen dissociation from phosphate was studied. [Copyright &y& Elsevier]

Abstract: π-Complexes consisting of silver salts such as AgBF4 and AgCF3SO3 dissolved in poly(styrene-b-butadiene-b-styrene) (SBS) block copolymers have been prepared for use as facilitated olefin transport membranes. Facilitated olefin transport is not observable up to the silver mole fraction of 0.14, a threshold concentration, above which it increases almost linearly with the silver salt concentration. FT-IR spectra of these complexes show that silver ions selectively coordinate with the Cf PB blocks up to the silver mole fraction of 0.14, and that the coordinative interaction of the silver ion with aliphatic Cnger than that with aromatic Cstingly, the bicontinuous morphology of the neat SBS block copolymer prepared from THF solution persists in the SBS complex with the salt concentrations less than 0.14. At high silver salt concentrations, the PS domains are additionally coordinated by silver ions and thus the morphology transition occurs from bicontinuous to lamellar. The threshold silver concentration of 0.14 for the facilitated olefin transport is nearly coincident with the composition at which the silver ions start coordinating with the aromatic Cf the PS blocks, suggesting their important role in determining overall transport properties. Therefore, we have shown that the transport properties of the SBS complex membranes are significantly affected by the coordinative interaction of the block copolymers with the silver ions and their membrane morphology. [Copyright &y& Elsevier]

Abstract: Polymer electrolyte membranes featuring ionic channels have been prepared by sulfonation of crosslinked poly(vinyl alcohol)/polyrotaxane membranes. The ionic channels were prepared using rod-like polyrotaxanes, created as an inclusion complex between poly(ethylene glycol) (PEG) and α-cyclodextran. The size of the polyrotaxane was controlled by the molecular weight of PEG. Proton conductivity as well as methanol permeability increased as the amount of sulfonated polyrotaxane inside the membrane increased. Sulfonation of the membrane increased with increasing amount of polyrotaxane, as confirmed by determination of its ionic exchange capacity. While the proton conductivity showed no significant dependence on the size of the polyrotaxanes, resistance to methanol transport depended on their size, implying a barrier role for these polyrotaxanes within the membrane. Well-dispersed polyrotaxane inside the membrane, as a mimic of ionic channels, played a role in transporting proton as well as in blocking methanol crossover, indicating that this concept to prepare membranes may prove useful in direct methanol fuel cell applications. [Copyright &y& Elsevier]

Abstract: The reduction of silver ions to silver nanoparticles is an essential issue in polymer/silver salt complex membranes for facilitated olefin transport, because it has a critical influence on the long-term stability of membrane performance. In this study, the role of anions for the formation of silver nanoparticles in polymer/silver salt complexes was investigated. This role was assessed for the complexes of poly(N-vinyl pyrrolidone) (PVP) with three silver salts including AgBF4, AgCF3SO3, and AgNO3. Especially, UV irradiation to the membranes was used to clearly investigate the reduction behavior of silver ions. Separation performance test, UV–vis spectroscopy and transmission electron microscopy (TEM) clearly show that the reduction rate of silver ions strongly depends on the counteranions of salt, and has the following order: AgBF4 >AgCF3SO3 >AgNO3. This behavior of the formation of silver nanoparticles in polymer/silver salt complex membranes is explained in terms of the interaction strength of silver ions with the carbonyl oxygens of polymer, and that of silver ions with counteranions. It is concluded that when the former interaction is strong and the latter one is weak, the reduction rate of silver ions to silver nanoparticles is fast, and vice versa. These interactions were characterized using FT-IR, FT-Raman spectroscopy, and theoretical ab initio calculation. [Copyright &y& Elsevier]

Abstract: The effect of amino acids such as asparagine, valine, glutamic acid and glycine on silver ion activity as a olefin carrier in membrane consisting of silver ions dissolved in poly(2-ethyl-2-oxazoline) (POZ) has been investigated. The presence of amino acids leads to the weakened interaction of the silver ion with its counteranion resulting from the electrostatic interaction between counteranion and NH3+ of amino acids, as confirmed by FT-IR spectra. As a result, the mixed gas permeances and selectivities of propylene/propane through POZ/AgBF4 or POZ/AgNO3 membranes intriguingly increased upon addition of the amino acids. However, the improvement of separation performance is strongly dependent on the type and the concentration of amino acids. Among the amino acids tested, the presence of asparagine containing amide group was found to improve the separation performance of the membranes most significantly. On the other hand, the performance of membrane with lysine containing amine group was the lowest, indicating the amine is not the effective ligand for silver ion in facilitated olefin transport membranes. [Copyright &y& Elsevier]

Abstract: Previously we have found that the facilitated olefin transport through polymer/silver complex membranes is sensitive to the type of the counteranion of salt; the separation performances including the permeance and selectivity of propylene/propane are in the order of AgBF4>AgCF3SO3AgNO3. Here the polymer/silver salt complex membranes consisting of two mixed salts dissolved in poly(2-ethyl-2-oxazoline) (POZ) were prepared and tested for the separation of propylene/propane mixtures. Upon mixing AgNO3 with AgBF4 or AgCF3SO3, the selectivity of propylene/propane unusually increased in certain composition ranges. The permeation behavior was interpreted in terms of both the activity of silver ion as olefin carrier and the structural change of polymer electrolyte membranes using FT-IR spectroscopy and wide angle X-ray scattering (WAXS). As a result, the anomalous enhancement of selectivity was attributable mainly to the structural compactness of membranes, resulting from the increased transient cross-links of polymer chains by coordination of small sized AgNO3. [Copyright &y& Elsevier]

Abstract: Highly efficient proton-exchange membranes (PEMs) have been made by using polymer blends of water soluble poly(vinyl alcohol) and poly(styrene sulfonic acid-co-maleic acid) (i.e. PVA/PSSA–MA). Upon successive thermal and chemical treatments of the membranes, the methanol permeability decreased more than one order of magnitude compared with Nafion 117 but the proton conductivity was as high as 0.1Scm-1 at room temperature. The degrees of swelling of the membranes were controlled by adding a suitable crosslinker (i.e. glutaraldehyde) and varying the mole ratios of maleic acid groups to sulfonic acid groups. The characteristic hydrophilic/hydrophobic separation length of the crosslinked membrane (equilibrated in water) was shown to be smaller than that of Nafion 117 as inferred from the results of small-angle X-ray scattering (SAXS) analysis. Moreover, we could not observe the typical ionomer peak in the PVA/PSSA–MA membrane equilibrated with methanol from the SAXS profile, demonstrating very poor methanol affinity of the membrane matrix. It is believed that this structural feature contributes to the reduction of methanol permeability through the membranes. [Copyright &y& Elsevier]

Facilitated olefin transport membranes consisting of AgBF4 dissolved in poly(2-ethyl-2-oxazoline) (POZ) were prepared for use in propylene/propane separation. It was found that facilitated propylene transport through these membranes depends on their thickness. As the membrane thickness increases, the propylene permeability increases whereas the propane permeability remains almost constant, resulting in an increase in the membranes’ selectivity of propylene over propane. The concentration fluctuation model for facilitated transport in the solid state predicts a dependence of facilitated transport on thickness. In this note, we compare the dependence of the propylene permeability of POZ/AgBF4 membranes on their thickness with that predicted by the concentration fluctuation model. [Copyright &y& Elsevier]

Silver polymer electrolyte membranes consisting of poly(vinyl pyrrolidone) (PVP) and AgBF4 have previously exhibited remarkable separation performance with respect to propylene/propane gas mixtures. In this work, the effect of temperature on facilitated propylene transport is reported. The propylene permeance through the PVP/AgBF4 membranes decreased with increasing temperature, predominantly due to a decrease of the propylene concentration coordinated to silver ions, that is propylene solubility, as demonstrated by FT-IR spectroscopy. The propane permeance and the actual selectivity of propylene over propane decreased monotonously with increasing temperature. Unexpectedly, the propylene permeance further drops sharply when the temperature is increased higher than 70 °C. This anomalous behavior of the propylene permeance at temperatures above 70 °C can be explained by the deactivation of silver ions as active olefin carriers, i.e. the reduction of silver ions to silver metals. It is concluded that the silver ions as active olefin carriers rapidly convert to silver metals at temperatures above 70 °C, therefore becoming much less active olefin carriers, which results in the low propylene permeance. [Copyright &y& Elsevier]

A multinetwork structured urushi organogel was created using low-volatility gamma butyrolactone (GBL) solvent and Fe3+ ions. The urushi organogels were fabricated through chemical crosslinking with the oxidative polymerization of urushiol as well as physical crosslinking due to the coordination bonds with Fe3+ ions in the Fe3+/urushiol/GBL solution. The role of Fe3+ ions is to provide physical crosslinking sites via the coordination bond with the catechol functional moiety of urushiol and also to serve as the catalysts for the polymerization of urushiol. The gelation and characteristics of urushi organogels in GBL with different amounts of Fe3+ ions were investigated. The formation of urushi organogel by chemical crosslinking and physical coordination crosslinking was investigated by FT-IR, Raman spectroscopy and X-ray photoelectron spectroscopy. The presence of a physical coordination bond between the Fe3+ ion and the catechol moiety of urushiol provides reversible adhesive properties, which provide consistent tensile strength after reattaching the urushi organogel film. The stretchability as well as the reversibility in mechanical strength can provide the possibility for various applications of eco-friendly natural urushi. This research provides not only a method to prepare multinetwork natural urushi organogels using Fe3+ ions but also the great possibility of expanding the application area of natural urushi(ol)s. • Multicrosslinked natural urushi-based organogels with reversibility were prepared with Fe3+ ions. • Multicrosslinking was formed by covalent bonding and by physical crosslinks, such as coordination bonds and entanglement with the long side chain. • The gelation time depends on the solid content and the mole ratio of urushiol to Fe3+ ions. • Fe3+/urushi organogels enhance urushi's potential for diverse uses, surpassing its coating limitations. [ABSTRACT FROM AUTHOR]

Selective layered membranes were fabricated using electrospun Nafion/(polyvinyl alcohol (PVA) fibres on porous membranes for non-aqueous vanadium redox flow battery applications (RFB). Porous Celgard 2400 polypropylene membranes were chosen as a porous support because they have a high ionic conductivity with excellent mechanical and dimensional stability in acetonitrile. The layers composed of the electrospun polyelectrolyte (Nafion) fibres on the porous support provide selectivity while maintaining the ion conductivity through the porous membrane. The membranes showed low vanadium acetylacetonate (V(acac) 3 ) permeability in acetonitrile compared to that of the pristine Celgard porous membrane. The performance of a non-aqueous RFB based on V(acac) 3 with electrospun Nafion/PVA fibres surface-modified porous membranes was evaluated and compared to that of Nafion 212 and Neosepta AHA membranes. Low coulombic and energy efficiencies of 49% and 32%, respectively, were obtained for pristine Celgard porous membranes, which are comparable to the values of Neosepta AHA membranes, and this low efficiency is due to the non-selectivity of the pore in the Celgard membrane. The values increase with the accumulated thickness of the electrospun Nafion/PVA fibres, with the coulombic and energy efficiencies reaching 69% and 50%, respectively, which are even higher than those of the Nafion 212 dense membranes. It is considered that porous supports contribute to the mechanical stability, and electrospun polyelectrolyte fibres accumulated on the surface reduce the crossover of the redox active species, resulting in the high performance of RFBs. This result implies that the electrospun modification of the mechanically stable porous membrane may enable the successful use of a non-aqueous RFB for future energy storage systems. [ABSTRACT FROM AUTHOR]

Dual facilitated CO 2 transport membranes with good CO 2 /CH 4 separation were developed using electrospun polyelectrolyte and room temperature ionic liquids (RTILs). Electrospinning was used to fabricate sites for the fixation of the RTIL carrier using polyelectrolyte as well as pores for the impregnation of the RTIL. 1-Hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF 4 ]) and 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF 6 ]) were chosen as CO 2 carriers for the facilitated transport membrane. The CO 2 carrier is present in two phases; one is liquid impregnated into the pores, and the other is located at fixed sites on a solid polyelectrolyte matrix. Two different electrospun composite membranes were prepared by the adsorption of RTIL onto electrospun polyvinylpyrrolidone (PVP) membranes with or without polyelectrolyte (Nafion). The polyelectrolyte Nafion provides fixation sites for the RTIL as well as the formation of pores, whereas PVP only provides pores for impregnation of the RTIL. The ideal CO 2 /CH 4 separation factors and permeances of electrospun PVP/Nafion composite membranes with RTIL were higher than those of supported ionic liquid membrane, and the CO 2 /CH 4 selectivity was found to be 26.3 with a CO 2 permeance of 19 GPU for electrospun PVP/Nafion composite membrane containing [hmim][PF 6 ]. The CO 2 permeance improved ca. 10% over that of dense composite membrane containing RTIL due to the dual facilitated transport both in liquid and solid-like phase. [ABSTRACT FROM AUTHOR]

Abstract: The ideal separation factor for propylene over propane approached 3.2 through the use of room temperature ionic liquids (ILs) such as 1-methyl-3-octyl imidazolium nitrate (MOIM+NO3 −, 98%) and 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIM+BF4 −, 98%), which may be attributable to facilitated olefin transport via specific and reversible interactions between ILs and propylene, but not propane. Specific and reversible interactions were verified experimentally from transient sorption/desorption data and FT-IR spectroscopy and theoretically by quantum mechanical calculations. The mixed gas selectivity for propylene/propane mixtures (50/50vol%) was 2.8 through ILs whereas with PEG 400 (Mw=400), which has nearly the same viscosity, the selectivity was only 1.2. This study demonstrated for the first time facilitated olefin transport through ILs. [Copyright &y& Elsevier]

Abstract: Highly branched, jacks-like ZnO nanorods architecture were explored as a photoanode in dye-sensitized solar cells, and their photovoltaic performance was compared with that of branch-free ZnO nanorods photoanodes. The highly branched network and large pores of the jacks-like ZnO nanorods electrodes enhances the charge transport, and electrolyte penetration. Thus, the jacks-like ZnO nanorods DSSCs render a higher conversion efficiency of η =1.82% (V oc =0.59V, J sc =5.52mAcm−2) than that of the branch-free ZnO nanorods electrodes (η =1.08%, V oc =0.49V, J sc =4.02mAcm−2). The incident photon-to-current conversion efficiency measurements reveal that the jacks-like ZnO nanorods DSSCs exhibit higher internal quantum efficiency (∼59.1%) than do the branch-free ZnO nanorods DSSC (∼52.5%). The charge transfer resistances at the ZnO/dye/electrolyte interfaces investigated using electrochemical impedance spectroscopy showed that the jacks-like ZnO nanorods DSSC had high charge transfer resistance and a slightly longer electron lifetime, thus improving the solar-cell performance. [Copyright &y& Elsevier]

Abstract: Color-stable hydrogenated Bisphenol A (HBA) epoxy adhesives, containing organic–inorganic hybrid nanomaterials, were prepared and their properties investigated. Poly(propylene glycol)bis(2-aminopropyl ether) (D230) was used as the room temperature curing agent, and functional organic–inorganic hybrid nanomaterials, to tailor the adhesives, were prepared by a sol–gel reaction of 3-glycidoxypropyltrimethoxysilane and tetraethoxysilane. The commercial polyhedral oligomeric silsesquioxanes (POSS) having epoxy functional groups were also used. The concentration dependence of different nanomaterials, containing epoxy functional group for HBA/D230 adhesives, was studied. The tensile strength increased with the addition of nanomaterials having glycidyl epoxy group; however, the dependence varied with the size, the number of functional groups, and the amount of the addition. HBA/D230 adhesives containing different amounts of nanomaterials, whose compositions are similar to that of granite, were applied to the Korean granite and the results were compared with those obtained by using commercial adhesives, which have the problem of significant color change and high viscosity. The mechanical properties of HBA/D230 adhesives, containing POSS having glycidyl epoxy group, are found to be similar to those of commercial adhesives. Besides, it has low viscosity and long-term color stability. [Copyright &y& Elsevier]

Abstract: The effect of ionic liquids on the formation of a partial positive charge on the surface of silver nanoparticle and its subsequent effect on facilitated olefin transport were investigated. Three different ionic liquids of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4 −), 1-butyl-3-methylimidazolium triflate (BMIM+Tf−), and 1-butyl-3-methylimidazolium nitrate (BMIM+NO3 −) were employed to control the positive charge density of the surface of silver nanoparticles. The positive charge density of the silver nanoparticles, as characterized by the binding energy of the silver atom, was in the following order: BMIM+BF4 −/Ag≫BMIM+Tf−/Ag>BMIM+NO3 −/Ag. This order was consistent with the tendency of ionic liquids to form free ions. The best separation performance for the propylene/propane mixtures was a mixed gas selectivity of 17 and a permeance of 7GPU through a composite membrane consisting of BMIM+BF4 −/Ag. A better separation performance for olefin/paraffin mixtures was observed with a higher positive charge density of the silver nanoparticles. It was therefore concluded that facilitated olefin transport was a direct consequence of the surface positive charge of the silver nanoparticles induced by ionic liquids. [Copyright &y& Elsevier]

Abstract: Proton exchange membranes based on Nafion/poly(p-phenylene vinylene) (PPV) composites were prepared by the heat treatment of a Nafion/PPV precursor, and investigated regarding their applicability for direct methanol fuel cells (DMFCs). The power density of MEA using Nafion/PPV composites was increased with increasing the PPV precursor concentration of the precursor solutions and reached 34mW/cm2, which is much greater than that using bare Nafion (∼26mW/cm2). The improved MEA performance was primarily due to a significant decrease in the methanol permeability with only a minimal loss of the ionic conductivity through the formation of PPV grains inside of the ionic channels and on the Nafion surface. The structure and properties of the Nafion/PPV composites were characterized by UV–vis spectroscopy, scanning electron microscopy, ion exchange capacity, water contact angle, and water uptake. [Copyright &y& Elsevier]

Abstract: Solid-state silver polymer electrolyte membranes containing AgNO3 dissolved in poly(2-ethyl-2-oxazoline) (POZ) as an olefin carrier are not efficient for the separation of olefin/paraffin mixtures (selectivity ∼1). The addition of fumed silica nanoparticles into the POZ/AgNO3 complex membranes, however, resulted in a surprisingly significant enhancement of the permeance and selectivity (higher than 80) for propylene/propane mixtures. These enhancements are explained in terms of the silver ion activity in olefin coordination. FT-IR, X-ray photoelectron spectroscopy (XPS) and FT-Raman demonstrate that the silver ion activity continuously increases by Lewis acid–base interactions upon incorporation of the silica nanoparticles up to 0.1 mole ratio of silica, above which it abruptly decreases. Furthermore, the structural change of polymer electrolyte membranes took place by the presence of nanoparticles, supported by the T g measurement. [Copyright &y& Elsevier]

A macrovoid-free, porous membrane with a sponge-like structure was obtained by phase inversion of a polyimide (PI)/γ-butyrolactone (GBL)/water system, whereas a membrane with a finger-like structure was obtained from a PI/N-methyl-2-pyrrolidinone (NMP)/water system. In this study, the effect of the molecular weight of poly(vinyl pyrrolidone) (PVP) additive (Mw: 360k and 40k) in two systems on membrane morphology has been investigated by the differences in phase separation rates and miscibility gaps. On addition of PVP into the PI casting solutions, the two systems exhibited significantly different membrane morphologies; the former augmented macrovoid formation while the latter suppressed formation of finger-like structures. The membrane morphology and the phase separation rate significantly depend on the molecular weight of PVP in PI/NMP/water system whereas those do insignificantly in PI/GBL/water system. The cloud points representing the miscibility gap do not depend on the molecular weight of PVP in both systems very much. Therefore, it is suggested that the morphology change in the PI/NMP/water system is mostly due to the change in the phase separation rate caused by the change in the solution viscosity upon addition of PVP. However, in the PI/GBL/water system, the molecular weight effect of PVP is not as significant as in the PI/NMP/water system, and the morphology change seems to be primarily due to the change in the miscibility gap. [Copyright &y& Elsevier]

Polymer electrolyte membranes consisting of AgBF4 dissolved in poly(ethylene phthalate) (PEP) exhibit significantly better long-term stability of performance in the separation of propylene/propane mixtures than AgBF4 in poly(2-ethyl-2-oxazoline) (POZ) membranes. This improvement in stability is due to the suppression of the reduction of silver ions to silver metal nanoparticles by the formation of stable chelates between the phthalic groups of PEP and silver ions, which was confirmed by the observation of a large shift of the PEP C&z.dbnd6;O stretching band with the addition of AgBF4; the peak shift for PEP/AgBF4 is twice that for POZ/AgBF4. Transmission electron micrograph (TEM) results confirmed that the rate of silver metal nanoparticle formation in PEP/AgBF4 is significantly lower than that in POZ/AgBF4. We conclude that the strong coordination between phthalic groups in PEP and silver ions which results in the formation of stable chelates is of pivotal importance in preventing the reduction of silver ions to silver metal and consequently in improving the performance of the membrane in the separation of propylene/propane mixtures. [Copyright &y& Elsevier]

The facilitated transport membranes, AgClO4-CA (cellulose acetate) and AgBF4-CA were prepared and tested for the separation of isoprene/pentane mixture. The maximum selectivities for isoprene over pentane were found to be 53 and 83 for AgClO4-CA and AgBF4-CA membranes, respectively. FT-IR and UV-Vis studies show that the silver ions in the membranes are coordinated by the carbonyl groups of CA. Reversible diene coordination to silver ions was observed by FT-IR and UV-Vis studies. Treatment of the AgBF4-CA membrane placed in a gas cell with isoprene produces an isoprene-coordinated membrane in which the coordinated isoprene is easily replaced by other diene compounds such as trans-piperylene and 1,3-butadiene. [Copyright &y& Elsevier]