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Sulfone
Kinds of Sulfone Terms modified by Sulfone Selected AbstractsSilver Acetate/TF-BiphamPhos-Catalyzed endo -Selective Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Ylides with Vinyl Phenyl SulfoneADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Gang Liang Abstract The first catalytic endo -selective 1,3-dipolar cycloaddition of azomethine ylides and vinyl phenyl sulfone has been developed successfully. The highly efficient silver acetate (AgOAc)/TF-BiphamPhos catalytic system exhibited high reactivity, excellent diastereoselectivity (>98:2), good enantioselectivity (67,92% ee) and broad substrate scope under mild conditions. [source] Asymmetrische Organokatalyse mit SulfonenANGEWANDTE CHEMIE, Issue 15 2010Martin Nielsen Dr. Abstract Die asymmetrische Organokatalyse hat sich zu einer effektiven Methode für die Herstellung optisch aktiver Verbindungen entwickelt. Während sich erste Untersuchungen im Wesentlichen auf die Verwendung einfacher Reagentien als Nachweis der Realisierbarkeit konzentrierten, befassen sich neuere Studien der asymmetrischen Organokatalyse nun damit, das Konzept auf ziel- und diversitätsorientierte Synthesen zu erweitern. Dank ihrer zahlreichen Transformationsmöglichkeiten und ihrer Fähigkeit zur Generierung nucleophiler wie auch elektrophiler Reaktionspartner spielen dabei Sulfone als Substrate eine besondere Rolle in der Organokatalyse. [source] Radiation Detection: Resistivity Responses in Functional Poly(Olefin Sulfone)/Carbon Nanotube Composites,ANGEWANDTE CHEMIE, Issue 1 2010Für die Detektion von Gammastrahlen wurde ein nicht-szintillierender organischer Sensor aus einem Blend von Poly(olefinsulfon) und Kohlenstoff-Nanoröhren entwickelt (siehe Bild). Die Polymere können nach der Polymerisation mit Pyren- und Bismut-Einheiten funktionalisiert werden (was durch Copolymerisation nicht gelingt), sodass ein systematischer Weg zu empfindlicheren Materialien verfügbar ist. [source] ChemInform Abstract: Magnesium Metal Mediated Reductive Trifluoromethylation of Aldehydes with Phenyl Trifluoromethyl Sulfone.CHEMINFORM, Issue 41 2010Yanchuan Zhao Abstract The method is suitable for enolizable and non-enolizable aldehydes via formation of a CF3 - species. [source] ChemInform Abstract: Regio- and Stereoselective Preparation of Dienylcarboxylic Acids and Dienylphosphonic Esters Using a (Z)-Alkenyl Sulfone,Titanocene(II) System.CHEMINFORM, Issue 31 2008Akitoshi Ogata Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Practical Synthesis of 4-Fluoro-2-(methylthio)benzylamine (V) and the Corresponding Sulfone (X) and Sulfonamide (XVI).CHEMINFORM, Issue 45 2007Debra S. Perlow Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of Tetracene Sulfoxide and Tetracene Sulfone via a Cascade Cyclization Reaction.CHEMINFORM, Issue 40 2007Yi-Chun Lin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The Epoxy-Ramberg,Baecklund Reaction (ERBR): A Sulfone-Based Method for the Synthesis of Allylic Alcohols.CHEMINFORM, Issue 31 2006Paul Evans Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The Epoxy-Ramberg,Baecklund Reaction (ERBR): A Sulfone-Based Method for the Synthesis of Allylic Alcohols.CHEMINFORM, Issue 31 2006Paul Evans Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Difluoromethyl Phenyl Sulfone, a Difluoromethylidene Equivalent: Use in the Synthesis of 1,1-Difluoro-1-alkenes.CHEMINFORM, Issue 4 2005G. K. Surya Prakash Abstract For Abstract see ChemInform Abstract in Full Text. [source] High Pressure-Promoted [2 + 2] Cycloaddition Reactions of 4-Methylphenyl 1,2-Propadienyl Sulfone with Enol Ethers.CHEMINFORM, Issue 25 2003Rene W. M. Aben Abstract For Abstract see ChemInform Abstract in Full Text. [source] Highly Efficient Biomimetic Oxidation of Sulfide to Sulfone by Hydrogen Peroxide in the Presence of Manganese meso -TetraphenylporphyrinCHINESE JOURNAL OF CHEMISTRY, Issue 6 2008Xian-Tai ZHOU Abstract Low amount of manganese meso -tetraphenyl porphyrin [Mn(TPP)] was used for highly efficient selective oxidation of sulfide to sulfone by hydrogen peroxide at room temperature. Sulfones were produced directly with yields generally around 90% while the catalyst concentration was only 4×10,5 mol·L,1. In a large-scale experiment of thioanisole oxidation, the isolated yield of sulfone (87%) was obtained and the turnover number (TON) reached up to 8×106, which is the highest TON for the oxidation systems of sulfide to sulfone catalyzed by metalloporphyrins. [source] Enhancement of Anodic Response for DMSO at Ruthenium Oxide Film Electrodes as a Result of Doping with Iron(III)ELECTROANALYSIS, Issue 2 2003Brett Abstract The oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2) is representative of numerous anodic oxygen-transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO2 -film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO2 films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO2 films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)-doped RuO2 -film electrode prepared using a deposition solution of 50,mM RuCl3 and 10,mM FeCl3 in a 1,:,1 mixture of isopropanol and 12,M HCl at an annealing temperature of 450,°C. The Levich plot (i vs. ,1/2) and Koutecky-Levich plot (1/i vs. 1/,1/2) of amperometric data for the oxidation of DMSO at an Fe(III)-doped RuO2 -film electrode configured as a rotated disk are consistent with an anodic response controlled by mass-transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)-doped RuO2 -film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100-,L injections of the three compounds are ca. 3.2×10,4,mM, i.e., ca. 32,pmol. [source] Ammonium perfluorooctanoate as a volatile surfactant for the analysis of N -methylcarbamates by MEKC-ESI-MSELECTROPHORESIS, Issue 22 2006Geert Van Biesen Abstract Ammonium perfluorooctanoate (APFOA) was investigated as an MS-friendly surfactant for the analysis of a mixture of ten N -methylcarbamates with MEKC-ESI-MS. Because of the relatively low boiling point of perfluorooctanoic acid (,190°C), APFOA can be introduced into a mass spectrometer without the adverse effects of less volatile surfactants such as SDS. With a BGE consisting of 50,mM APFOA/isopropanol (IPA) 98:2 and with 30,kV applied, a very fast separation (,6,min) was possible with only one pair of analytes comigrating. Using an experimental design with four factors (voltage, nebulizer pressure, concentration of APFOA, and concentration of IPA) we were able to resolve all analytes in just over 11,min. Sheath liquid composition and flow rate, drying gas temperature and flow rate, and fragmentor voltage were then optimized for maximum signal intensity and S/N. It was found that the faster method gave better S/N because of narrower peak widths, and detection limits in SIM mode were between 0.01 (aldicarb) and 0.08,mg/L (methomyl). Calibration curves were prepared with standards of 0.50, 1.00, and 2.00,mg/L for the analysis of samples obtained after SPE of tap water spiked with the ten N -methylcarbamates at a level of 10,µg/L. All analytes showed very good recoveries (>86%), except for the most polar analyte aldicarb sulfone (recovery of 73%), testifying for the potential use of APFOA for this kind of analyses. [source] An Expedient Synthesis of Perfluorinated Tetraazamacrocycles: New Ligands for Copper-Catalyzed Oxidation under Fluorous Biphasic ConditionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2006Augustin de Castries Abstract Conjugate additions of cyclam to perfluorohexyl vinyl sulfone and sulfoxide, which act as efficient fluorous Michael acceptors, readily give access to new fluoro-ponytail tetraazamacrocycles in good yields. The solubility of the N -tetrasubstituted macrocycles depends dramatically on the nature of the polar function (SO or SO2): the sulfoxide cyclam derivative is soluble in perfluorodecaline (pfd) and perfluoromethylcyclohexane (pfmc) while the sulfonyl derivative is almost insoluble in organic or fluorous solvents. In agreement with the well known affinity of cyclam for copper(II) ions, stable copper complexes of the fluorous macrocyclic ligands have been isolated and characterized. In chloroform/methanol, complexes with four perfluorinated tails have been obtained from reaction of the tetra- N -perfluorohexylsulfinyl-substituted macrocycle with copper nitrate and copper perfluorocarboxylate. In trifluoroethanol, a selective retro-Michael reaction has been observed and the same reaction specifically gives copper complexes of the tri- N -substituted macrocycle. Complexes with three and four fluorous tails associated with perfluorocarboxylate counteranions are soluble in fluorous solvents (pfd and pfmc). These copper complexes were tested as catalysts for the oxidation of cyclohexene by molecular oxygen in the presence of tert -butyl hydroperoxide (tbhp). The oxidation reactions proceed under fluorous biphasic conditions and the catalyst can be recovered and reused. Quenching experiments indicate that cyclohexenyl hydroperoxide is the main oxidation product of the reaction performed with or without tbhp. Interestingly, these perfluorinated copper complexes are good, recyclable catalysts for the oxidation of cyclohexene by molecular oxygen without tbhp at room temperature and 65 °C.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] 3,5-Bis(trifluoromethyl)phenyl Sulfones in the Julia,Kocienski Olefination , Application to the Synthesis of Tri- and Tetrasubstituted OlefinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2006Diego A. Alonso Abstract 3,5-Bis(trifluoromethyl)phenyl (BTFP) sulfones 8a,d are successfully employed in the modified Julia olefination reaction with carbonyl compounds employing phosphazene base P4- tBu at room temp. in THF, affording tri- and tetrasubstituted olefins in good yields. The Julia,Kocienski olefination between primary alkyl BTFP sulfones 8a,b and aromatic and aliphatic ketones affords the corresponding trisubstituted alkenes in good yields and low stereoselectivities. On the other hand, higher yields and stereoselectivities are obtained in the synthesis of trisubstituted olefins through the other approach, the coupling of secondary alkyl BTFP sulfones 8c,d with aliphatic, aromatic and ,,,-unsaturated aldehydes. For the first time, tetrasubstituted olefins are synthesized by means of the Julia,Kocienski protocol when the isopropyl BTFP sulfone 8c reacts with aliphatic and aromatic ketones, employing P4- tBu as base at THF reflux. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis and Properties of Oligodeoxynucleotide Analogs with Bis(methylene) Sulfone BridgesHELVETICA CHIMICA ACTA, Issue 9 2003Bernd Eschgfäller A convergent, solution-phase synthesis was developed for the bis(methylene) sulfone-bridged oligodeoxynucleotide analogs (SNA) 5,-d(HOCH2 -Tso2Tso2Tso2Cso2Tso2Tso2Tso2T-CH2SO)-3, (35b) and 5,-d(HOCH2 -Tso2Tso2Tso2Tso2Tso2Tso2Tso2T-CH2SO)-3, (34c) (SO2 corresponds to CH2SO2CH2 instead of OP(O)(O,)(O). In these, the phosphodiester linkages are replaced by non-ionic bis(methylene) sulfone linkers. The general strategy involved convergent coupling of 3,,5,-bishomo- , - D -deoxyribonucleotide analogs functionalized at the 6,-end (CH2C(5,)) as bromides or mesylates and at the CH2C(3,) position as thiols, with the resulting thioether being oxidized to the corresponding sulfone. A single charge was introduced at the terminal CH2C(3,) position of the octamers to increase their solubility in water. During the synthesis, it became apparent that the key intermediates generated secondary structures through either folding or aggregation in a variety of solvents. This generated unusual reactivity and was unique for very similar structures. For example, although the dimeric thiol d(BzOCH2 -Tso2C-CH2SH) (14b) was a well-behaved synthetic intermediate, the tetrameric thiol d(TrOCH2 -Tso2Tso2Tso2toC-CH2SH) derived from the corresponding thioacetate was rapidly converted to a disulfide by very small amounts of oxidant (28,29, Scheme,6), while the analogous tetrameric thiol d(BzOCH2 -Tso2TsTso2T-CH2SH) (26), differing only by a single heterocycle, was oxidized much more slowly (Bz=PhCO, Tr=Ph3C, to=2-MeC6H4CO (at N4 of dc)). The sequence-dependent reactivity, well known in many classes of natural products (including polypeptides), is not prominent in natural oligonucleotides. These results are discussed in light of the proposal that the repeating negative charge in nucleic acids is key to their ability to serve as genetic molecules, in particular, their capability to support Darwinian evolution. The ability of 5,-d(HOCH2 -Tso2Tso2Tso2Cso2Tso2Tso2Tso2T-CH2SO)-3, (35b) to bind as a third strand to duplex DNA was also examined. No triple-helix-forming propensity was detected in this molecule. [source] Allylic Sulfones Containing Triene Moieties as Key Synthons for Carotenoid SynthesisHELVETICA CHIMICA ACTA, Issue 7 2003Minkoo Ji An efficient synthetic method for the allylic sulfone 2 containing a conjugated triene moiety has been proposed involving i) coupling of allylic sulfones 4 with the C5 bromoallylic sulfide 5, ii) base-promoted dehydrosulfonation in the presence of allylic sulfide, and iii) selective oxidation of the resulting trienyl sulfide to the corresponding sulfone. Total synthesis of lycopene starting from the C15 allylic sulfone 2b has been described, where the new C10 bis(chloroallylic) sulfone 11 proved to be a useful substitute for the C10 bis(chloroallylic) sulfide 3, which did not require the problematic chemoselective sulfur oxidation in a conjugated polyene. [source] Refined aquatic risk assessment for aldicarb in the United StatesINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2010Dwayne RJ Moore Abstract Aldicarb is a systemic insecticide applied directly to soil and to control mites, nematodes, and aphids on a variety of crops (e.g., cotton, potatoes, peanuts). It is highly soluble in water (6,000 mg/L) and mobile in soils (Koc,=,100). As a result, aldicarb has the potential to be transported to aquatic systems close to treated fields. The US Environmental Protection Agency (USEPA) recently conducted an aquatic screening-level ERA for aldicarb as part of the re-registration review process. We conducted a refined risk assessment for aldicarb to characterize better the risks posed by aldicarb to fish and invertebrates inhabiting small freshwater ponds near agricultural areas. For the exposure assessment, tier II PRZM/EXAMS (Predicted Root Zone Model [PRZM] and Exposure Analysis Modelling System [EXAMS]) modelling was conducted to estimate 30-y distributions of peak concentrations of aldicarb and the carbamate metabolites (aldicarb sulfoxide, aldicarb sulfone) in surface waters of a standard pond arising from different uses of aldicarb. The effects assessment was performed using a species sensitivity distribution (SSD) approach. The resulting risk curves as well as available incident reports suggest that risks to freshwater fish and invertebrates from exposure to aldicarb are minor. The available monitoring data did not provide conclusive evidence about risks to aquatic biota. Integr Environ Assess Manag 2010; 6:102,118. © 2009 SETAC [source] The First General and Selective Palladium(II)-Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone-Ligated Palladium(0) Complex, Organoboron, and Alcohol SolventADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Yoshihiko Yamamoto Abstract Methoxycarbonylation of aryl- and alkenylboron compounds was performed using the palladium(II) acetate/triphenylphosphine [Pd(OAc)2/PPh3] catalyst with p -benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert -butanol afforded various p -chlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism. [source] Silver Acetate/TF-BiphamPhos-Catalyzed endo -Selective Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Ylides with Vinyl Phenyl SulfoneADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Gang Liang Abstract The first catalytic endo -selective 1,3-dipolar cycloaddition of azomethine ylides and vinyl phenyl sulfone has been developed successfully. The highly efficient silver acetate (AgOAc)/TF-BiphamPhos catalytic system exhibited high reactivity, excellent diastereoselectivity (>98:2), good enantioselectivity (67,92% ee) and broad substrate scope under mild conditions. [source] Asymmetric Sulfoxidation of Thioethers with Hydrogen Peroxide in Water Mediated by Platinum Chiral CatalystADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Alessandro Scarso Abstract Easy stereoselective oxidation of prochiral aryl alkyl sulfides 2 to the corresponding sulfoxides can be achieved in water-surfactant medium with inexpensive hydrogen peroxide mediated by the chiral platinum diphosphine complex {[(R)-BINAP]Pt(, - OH)}2(BF4)2 (1). Remarkable key features of general interest are (i) easy isolation of the products from catalyst by simple diethyl ether/water-surfactant two phase separation, (ii) catalyst loading as low as 1% mol, (iii) good yields, sulfoxide 3 to sulfone 4 ratio up to 200,:,1 and enantioselectivities up to 88%, (iv) mild experimental conditions. [source] Preparation and characterization of epoxy/kaolinite nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Xinnian Xia Abstract Epoxy/kaolinite nanocomposites were prepared by adding the organically modified layered kaolinite to an epoxy resin [biphenyl phenol novolac epoxy resin (BPNE)] with 4,4,-diamino biphenyl sulfone (DDS) as a curing agent. The dispersion state of the kaolinite within crosslinked epoxy-resin matrix was examined by X-ray diffraction (XRD) and transmission electron micrograph (TEM). The effects of kaolinite on thermal properties were investigated and discussed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Experimental results show that BPNE/kaolinite nanocomposites exhibit improved thermal than pure BPNE. When the kaolinite content is 5 wt %, the BPNE/kaolinite nanocomposites show the best thermal properties. These results indicate that nanocomposition is an efficient and convenient method to improve the thermal properties of BPNE. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Possibilities of polymer-aided dyeing of cotton fabric with reactive dyes at neutral pHJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010B. J. Agarwal Abstract Water-soluble polymers have versatile application, viz., water-soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water-soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3-dichlorohydrin and hexamethylene tetramine-hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Chemical modification of polyethersulfone nanofiltration membranes: A reviewJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009B. Van der Bruggen Abstract Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self-assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Effect of addition of organic microspheres on proton conductivity property of sulfonated poly(arylene ether sulfone) membraneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Cui Liang Abstract Sulfonated poly(arylene ether sulfone) (SPAES)/polystyrene(PS) and SPAES/polystyrene sulfonic acid (PSSA) composite membranes were studied for a proton-exchange membrane used in a fuel cell. PS microspheres were synthesized by emulsion polymerization. PSSA microspheres with 5.3 mmol/g ion-exchange capacity (IEC) were prepared by sulfonation of PS microspheres. The composite membranes were prepared by solution casting. SPAES/PSSA composite membranes showed higher proton conductivity than a SPAES membrane because of the IEC improved by adding PSSA. Although the addition of PSSA also brought about the increase of a methanol permeability, the proton/methanol selectivity defined as the ratio of the proton conductivity to the methanol permeability was improved at low humidity by adding 5 wt % of PSSA microspheres. Differential scanning calorimetry results indicated that the amount of free water varied in the cases of the addition of the two kinds of organic microspheres. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Viscosity behavior of microwave-heated and conventionally heated poly(ether sulfone)/dimethylformamide/lithium bromide polymer solutionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Ani Idris Abstract This article investigates the viscosity behavior of new membrane dope solutions of poly(ether sulfone) (PES) and dimethylformamide with low-molecular-weight halogenated lithium bromide (LiBr) additives prepared with two different techniques: (1) a microwave (MW) technique and (2) a conventional heating (CH) technique. In addition, the influence of different concentrations of anhydrous halogenated LiBr additives (0,5 wt %) on the viscosity behavior is analyzed. The viscosity of the dope solutions was assessed with a conical rheometer equipped with a high-viscosity adapter. The results revealed that the pure PES solutions prepared by the MW and CH techniques exhibited pseudoplastic and Newtonian behavior, respectively. Both the MW and CH PES solutions containing the LiBr additives exhibited dilatant behavior, which obeyed the power law. The apparent viscosity of all the dope solutions prepared with the MW technique was lower than that of those prepared with the CH technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Sulfonated poly(ether imide) and poly(ether sulfone) blends for direct methanol fuel cells.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Abstract This investigation examines characteristics of sulfonated polyether imides (SPEI) with various ion exchange capacity values (IEC) and completes previous work to enable its blends to be adopted as polyelectrolyte in direct methanol fuel cells (DMFC). Polyether imides (PEI) were sulfonated by using chlorosulfonic acid as the sulfonating agent and chloroform as the solvent. The structure of SPEI was observed by FTIR and 1H NMR. The sulfonate or sulfonic acid content of the polymers, expressed as a number per repeat unit of the polymer, was accurately determined by elemental analysis and conductometric titration. Physical properties such as solubility, intrinsic viscosities, thermal stability, and glass transition temperature (Tg) were studied for both PEI and SPEI. TGA-FTIR verified that sulfonic groups, attached to the aromatic ring in the PEI backbone, are split at 230,350°C, but the main-chain splitting temperature of SPEI is similar to that of pure polymer. The sulfonated samples exhibited good solubilities and increased glass transition temperatures (Tg values) as degree of sulfonation (DS) increased; two Tg values were detected when IEC was sufficiently high. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Preparation of poly(ether sulfone) nanofibers by gas-jet/electrospinningJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Yi Lin Abstract Poly(ether sulfone) (PES) nanofibers were prepared by the gas-jet/electrospinning of its solutions in N,N -dimethylformamide (DMF). The gas used in this gas-jet/electrospinning process was nitrogen. The morphology of the PES nanofibers was investigated with scanning electron microscopy. The process parameters studied in this work included the concentration of the polymer solution, the applied voltage, the tip,collector distance (TCD), the inner diameter of the needle, and the gas flow rate. It was found from experimental results that the average diameter of the electrospun PES fibers depended strongly on these process parameters. A decrease in the polymer concentration in the spinning solutions resulted in the formation of nanofibers with a smaller diameter. The use of an 18 wt % polymer solution yielded PES nanofibers with an average diameter of about 80 nm. However, a morphology of mixed bead fibers was formed when the concentration of PES in DMF was below 20 wt % during gas-jet/electrospinning. Uniform PES nanofibers with an average diameter of about 200 nm were prepared by this electrospinning with the following optimal process parameters: the concentration of PES in DMF was 25 wt %, the applied voltage was 28.8 kV, the gas flow was 10.0 L/min, the inner diameter of the needle was 0.24 mm, the TCD was 20 cm, and the flow rate was 6.0 mL/h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Effect of sequence distribution of PES/PEES random, block, and alternative copolymers on excimer formation in solutionJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Xiao-Ming Zhou Abstract Three copolymers of poly(ether sulfone) and poly(ether ether sulfone) with the same composition but different sequence distribution were synthesized by three kinds of methods. Their molecular aggregation in dichloromethane was studied by fluorescence spectrophotometer and electron microscope. The experimental results revealed that the formation of intermolecular excimers in alternative copolymer (A50) dichloromethane solution were observed at a A50 concentration about 1.6 × 10,2 g/mL by the fluorescence analysis, but the formation of intermolecular excimers in dichloromethane were not found for random copolymer (R50) and block copolymer (B50). The electron micrograph of three copolymer films, heat-treated at 200°C for 7 days, presented a diffraction micrograph, which suggest that three copolymer molecular aggregation is changed from a randomly coiled amorphous phase to an ordered one, and the order structure of alternative copolymer (A50) was the most distinct in three copolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] | |||||||||||||||||||||||||||||||||||||