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Michael D. Guiver - One of the best experts on this subject based on the ideXlab platform.
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Polysulfones with Phenylalanine Derivatives as Chiral Selectors – Membranes for Chiral Separation
2016Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. GuiverAbstract:Abstract: Polysulfone with a derivative of phenylalanyl residue as a chiral selector (PSf-Ac-D-Phe or PSf-Ac-L-Phe) were prepared by polymer reaction of benzylamine-modified Polysulfones with N--acetyl-D-phenylalanine or N--acetyl-L-phenylalanine. Both Polysulfones having a chiral selector gave durable self-standing membranes. The specific rotations of those polymers revealed that the chiral selectors were successfully introduced into the Polysulfone. PSf-Ac-D-Phe membrane incorporated L-Glu in preference to D-Glu and vice versa. The chiral separation ability was studied by applying a concentration gradient as a driving force for membrane transport. Permselectivities for those two types of membrane reflected their adsorption selectivities. PSf-Ac-D-Phe membrane selectively transported L-Glu and vice versa. Predicted permselectivities by adopting membrane resistance coincided with the observed ones
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Polyamide thin-film composite membranes based on carboxylated Polysulfone microporous support membranes for forward osmosis
Elsevier Science B.V. Amsterdam., 2013Co-Authors: Michael D. GuiverAbstract:Due to its simple process and low energy consumption, forward osmosis (FO) has gained significant attention in the fields of portable hydration bags, desalination, landfill leachate treatment, and brine concentration. However, current state-of-the-art reverse osmosis (RO) membranes show relatively low water fluxes in FO processes due to high internal concentration polarization (ICP) and high mass transfer resistance in commercially available microporous support membranes. In this study, carboxylated Polysulfones (CPSFs) were synthesized via direct Polysulfone (PSF) functionalization and considered as hydrophilic, mechanically stable microporous support membranes. The incorporation of hydrophilic groups into hydrophobic polymer backbones often reduces mechanical strength due to excessive water swelling. However, the mechanical properties of CPSFs (degree of substitution, DS = 0.49-0.85) were similar to those of pristine PSF, and they retained their hydrophilic nature. Microporous CPSF membranes were prepared in various conditions, and FO water fluxes and salt passages of polyamide thin-film/CPSF composite membranes were measured and compared with each other. CPSF-based FO membranes showed significantly higher water fluxes (water flux in FO mode: 18 L/m(2) h, salt passage: 2.2 g/m(2) h under 1 M MgCl2 as a draw solution, active layer facing DI water) than PSF-based FO membranes (10.5 L/m(2) h, 1.5 g/m(2) h at the same conditions), which might be due to enhanced hydrophilicity and reduced ICP. (c) 2013 Crown. Published by Elsevier B.V. All rights reserved.The World Class University (WCU) Program of the Ministry of Education, Science, and Technology (MEST) in Korea supported this study
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Polysulfones with phenylalanine derivatives as chiral selectors membranes for chiral separation
Journal of Membrane and Separation Technology, 2012Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. GuiverAbstract:Polysulfone with a derivative of phenylalanyl residue as a chiral selector (PSf-Ac-D-Phe or PSf-Ac-L-Phe) were prepared by polymer reaction of benzylamine-modified Polysulfones with N-a-acetyl-D-phenylalanine or N-a-acetyl-L-phenylalanine. Both Polysulfones having a chiral selector gave durable self-standing membranes. The specific rotations of those polymers revealed that the chiral selectors were successfully introduced into the Polysulfone. PSf-Ac-D-Phe membrane incorporated L-Glu in preference to D-Glu and vice versa . The chiral separation ability was studied by applying a concentration gradient as a driving force for membrane transport. Permselectivities for those two types of membrane reflected their adsorption selectivities. PSf-Ac-D-Phe membrane selectively transported L-Glu and vice versa . Predicted permselectivities by adopting membrane resistance coincided with the observed ones.
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electrospun nanofiber membranes from Polysulfones with chiral selector aimed for optical resolution
European Polymer Journal, 2012Co-Authors: Hiroaki Mizushima, Masakazu Yoshikawa, Michael D. Guiver, Gilles P. RobertsonAbstract:Abstract Polysulfones with three types of alanyl residue, such as N -α-acetylalanine (Ac-Ala-OH), N -α-benzoylalanine (Bzo-Ala-OH), and N -α-benzyloxycarbonylalanine (Z-Ala-OH), as chiral selectors were prepared by polymer reaction. The resulting modified Polysulfones showed chiroptical properties, indicating that the chiral selector residues were successfully introduced into the Polysulfone. Nanofiber membranes prepared from the polymeric materials showed adsorption selectivity toward mixtures of racemic Glu, which were adopted as model racemates. Flux values for the nanofiber membranes were enhanced two to three orders of magnitude in comparison with the corresponding typical membranes, but without reduction in permselectivity. In the present study, it is shown that nanofiber is a suitable membrane form not only for molecularly imprinted membranes, but it exhibits enhanced throughput in comparison with typical dense membranes without concurrent reduction in permselectivity.
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modified Polysulfones vi preparation of polymer membrane materials containing benzimine and benzylamine groups as precursors for molecularly imprinted sensor devices
Journal of Polymer Science Part A, 2003Co-Authors: Gilles P. Robertson, Michael D. Guiver, Francois Bilodeau, Masakazu YoshikawaAbstract:A modified Polysulfone containing benzylamine groups was synthesized as a reactive membrane material. Polysulfone was activated at the ortho-sulfone site by direct lithiation with n-butyllithium, and the resulting lithiated Polysulfone was then reacted with benzonitrile; this yielded a polymer with pendant benzimine groups. The structure was confirmed by NMR and IR spectroscopy and by the transformation of imine to ketone by acid hydrolysis. The polymeric benzimine was also reduced to benzylamine with sodium cyanoborohydride in an acidic medium. The structure and degree of substitution of both benzylamine derivatives were determined by NMR and IR spectroscopy. The modified Polysulfone containing benzylamine groups initiated the polymerization of N-carboxyanhydride of γ-benzyl-L-glutamate [Glu(OBzl)–NCA]. The side-chain oligopeptide of Glu(OBzl)–NCA attached to Polysulfone was converted into molecular recognition sites. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1316–1329, 2003
Yongdong Wang - One of the best experts on this subject based on the ideXlab platform.
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imidazolium functionalized Polysulfone hydroxide exchange membranes for potential applications in alkaline membrane direct alcohol fuel cells
International Journal of Hydrogen Energy, 2012Co-Authors: Gaohong He, Shuang Gu, Xuemei Wu, Liguang Du, Yongdong WangAbstract:Abstract A series of imidazolium-functionalized Polysulfones were successfully synthesized by chloromethylation-Menshutkin two-step method. PSf-ImOHs show the desired selective solubility: insoluble in alcohols (e.g., methanol and ethanol), and soluble in 50 vol.% aqueous solutions of acetone or tetrahydrofuran, implying their potential applications for both the alcohol-resistant membranes themselves and the ionomer solutions in low-boiling-point water-soluble solvents. PSf-ImOH also possesses very high thermal stability ( T OD : 258 °C), higher than quaternary ammonium and quaternary phosphonium functionalized Polysulfones ( T OD : 120 °C and 186 °C, repsectively). Ion exchange capacity (IEC) of PSf-ImOH membranes ranges from 0.78 to 2.19 mmol g −1 with degree of chloromethylation from 42% to 132% of original chloromethylated Polysulfone. As expected, water uptake, swelling ratio, and hydroxide conductivity increase with IEC and temperatures. With 2.19 mmol g −1 of IEC, the PSf-ImOH 132% membrane exhibits the highest hydroxide conductivity (53 mS cm −1 at 20 °C), higher than those of all other reported Polysulfone-based HEMs (1.6–45 mS cm −1 ) and other imidazolium-functionalized HEMs (19.6–38.8 mS cm −1 ). In addition, PSf-ImOH membranes have low methanol permeability of 0.8–4.7 × 10 −7 cm 2 s −1 , one order of magnitude smaller than that of Nafion212 membrane. All these properties indicate imidazolium-functionalized Polysulfone is very promising for potential applications in alkaline membrane direct alcohol fuel cells.
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imidazolium functionalized Polysulfone hydroxide exchange membranes for potential applications in alkaline membrane direct alcohol fuel cells
International Journal of Hydrogen Energy, 2012Co-Authors: Xiaoming Yan, Yongdong WangAbstract:Abstract A series of imidazolium-functionalized Polysulfones were successfully synthesized by chloromethylation-Menshutkin two-step method. PSf-ImOHs show the desired selective solubility: insoluble in alcohols (e.g., methanol and ethanol), and soluble in 50 vol.% aqueous solutions of acetone or tetrahydrofuran, implying their potential applications for both the alcohol-resistant membranes themselves and the ionomer solutions in low-boiling-point water-soluble solvents. PSf-ImOH also possesses very high thermal stability ( T OD : 258 °C), higher than quaternary ammonium and quaternary phosphonium functionalized Polysulfones ( T OD : 120 °C and 186 °C, repsectively). Ion exchange capacity (IEC) of PSf-ImOH membranes ranges from 0.78 to 2.19 mmol g −1 with degree of chloromethylation from 42% to 132% of original chloromethylated Polysulfone. As expected, water uptake, swelling ratio, and hydroxide conductivity increase with IEC and temperatures. With 2.19 mmol g −1 of IEC, the PSf-ImOH 132% membrane exhibits the highest hydroxide conductivity (53 mS cm −1 at 20 °C), higher than those of all other reported Polysulfone-based HEMs (1.6–45 mS cm −1 ) and other imidazolium-functionalized HEMs (19.6–38.8 mS cm −1 ). In addition, PSf-ImOH membranes have low methanol permeability of 0.8–4.7 × 10 −7 cm 2 s −1 , one order of magnitude smaller than that of Nafion212 membrane. All these properties indicate imidazolium-functionalized Polysulfone is very promising for potential applications in alkaline membrane direct alcohol fuel cells.
Patric Jannasch - One of the best experts on this subject based on the ideXlab platform.
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proton conducting aromatic polymers carrying hypersulfonated side chains for fuel cell applications
Advanced Functional Materials, 2007Co-Authors: Benoit Lafitte, Patric JannaschAbstract:Polysulfone main chains have been functionalized with hypersulfonated aromatic side chains where the sulfonic acid groups were highly concentrated on a local scale, with two acid groups placed on the same aromatic ring. This molecular design was implemented to promote the nanophase separation that takes place in proton-exchange membranes between the hydrophobic polymer main chain and the hydrophilic ionic groups responsible for the water uptake and conduction. Morphological investigations revealed that Polysulfones functionalized with disulfonaphthoxybenzoyl or trisulfopyrenoxybenzoyl side chains contained larger and more uniform ionic clusters, as compared to conventionally sulfonated Polysulfones where the acid groups are dispersed along the main chain. Membranes based on the polymers carrying hypersulfonated side chains formed efficient networks of water-filled nanopores upon hydration, which facilitated excellent levels of proton conductivity exceeding that of the commercial Nafion membrane at moderate water uptakes.
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Polysulfone ionomers for proton conducting fuel cell membranes 2 sulfophenylated Polysulfones and polyphenylsulfones
Electrochimica Acta, 2005Co-Authors: Lina Karlsson, Patric JannaschAbstract:Polysulfones and polyphenylsulfones having pendant phenyl groups with sulfonic acid units have been prepared by lithiation of the respective polymer, followed by reaction with 2-sulfobenzoic acid cyclic anhydride. The resulting ionomers were cast into membranes and properties such as thermal stability, ion-exchange capacity, water sorption and proton conductivity were evaluated. These membranes proved to have a high thermal stability, with a decomposition temperature between 300 and 350degreesC, and a high proton conductivity, 60 mS/cm at 70degreesC for a polyphenylsulfone with 0.9 sulfonic acid group per repeating unit measured at 100% relative humidity. Moreover, some of the membranes endured immersion in water at temperatures ranging from 20 to 150degreesC without swelling extensively, and therefore kept their mechanical stability under these conditions. It was also shown that these membranes retained a high conductivity up to 150degreesC under humidifying conditions. The combination of properties make these membranes potential candidates for fuel cells operating at temperatures above 100degreesC.
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Polysulfone ionomers for proton conducting fuel cell membranes sulfoalkylated Polysulfones
Journal of Membrane Science, 2004Co-Authors: Lina Karlsson, Patric JannaschAbstract:Polysulfones (PSUs) carrying short pendant alkyl side-chains with terminal sulfonic acid units have been prepared and studied as proton-conducting membrane materials. The first step in the preparation involved quenching of lithiated PSU with SO2 gas, resulting in sulfinated PSU. In the second step, the lithium sulfinate units on the polymer were reacted with sodium 2-bromoethanesulfonate, sodium 3-bromopropanesulfonate, or 1,4-butane sultone to produce sulfoethylated, sulfopropylated, or sulfobutylated PSUs, respectively. Analysis by thermogravimetry showed that membranes based on the sulfoalkylated polymers were stable up to approximately 300degreesC under N-2 atmosphere. Calorimetry measurements revealed that the modified polymers absorbed large amounts of non-freezing water, corresponding to 11-14 mol H2O/mol SO3H under immersed conditions. The proton conductivity of a membrane based on a PSU carrying 0.9 sulfopropyl chains per repeating unit was measured to be 77 mS/cm at 70degreesC under humidifying conditions. (C) 2003 Elsevier B.V. All rights reserved. (Less)
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sulfophenylation of Polysulfones for proton conducting fuel cell membranes
Macromolecular Rapid Communications, 2002Co-Authors: Benoit Lafitte, Lina Karlsson, Patric JannaschAbstract:Polysulfone has been sulfophenylated by lithiation and anionic reaction with 2-sulfobenzoic acid cyclic anhydride. This provides a new convenient method to modify Polysulfones by attaching pendant sulfonated phenyl groups via ketone links. Membranes of the sulfophenylated Polysulfones show promise for use in proton-exchange-membrane fuel cells. For example, a membrane with 0.9 sulfophenyl units per repeating Polysulfone unit and 30 wt.-% water was found to have a proton conductivity of 32 mS/cm at 60degreesC.
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Polysulfone b polystyrene block copolymers by mechanistic transformation from condensation polymerization to free radical polymerization
Polymer Bulletin, 2013Co-Authors: Yusuf Yagci, Cemil Dizman, Muhammet U KahveciAbstract:Synthesis of Polysulfone-b-polystyrene (PSU-b-PS) block copolymers by a combination of condensation polymerization and free radical polymerization processes are described. First, a new macroazoinitiator (MAI) containing Polysulfone (PSU) units was prepared by direct esterification of 4,4-azobis(4-cyanopentanoic acid) with α,ω-hydroxyl PSU telechelics at ambient conditions. The macroinitiator was then used in conventional free radical polymerization of styrene leading to the formation of desired block copolymers. In this process, initiating macroradicals were generated by thermal cleavage of the azo group present in the macroazoinitiator structure. The precursor Polysulfone macroazoinitiator (PSU-MAI) and resulting block copolymers were characterized by spectral analysis using FT-IR, 1H-NMR, GPC, TGA, and DSC.
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Thermal degradation characteristics of Polysulfones with benzoxazine end groups
Journal of Analytical and Applied Pyrolysis, 2012Co-Authors: Tugba Orhan, Sahin Ates, Jale Hacaloglu, Yusuf YagciAbstract:Abstract Thermal degradation behaviors of phenol and benzoxazine end-capped Polysulfone macromonomers (PSU-OH and PSU-P-a) and pre-cured PSU-P-a in the absence and presence of aniline and phenol based benzoxazine monomer (P-a) were investigated via pyrolysis mass spectrometry. A significant increase in thermal stability of both Polysulfone and polybenzoxazine chains upon polymerization of benzoxazine end groups was determined compared to phenol-ended Polysulfones and aniline based monofunctional polybenzoxazine. Thermal stability of both chain segments depends on concentration of benzoxazine monomer and the chain length of the Polysulfone chain.
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synthesis characterization and thermally activated curing of Polysulfones with benzoxazine end groups
Polymer, 2011Co-Authors: Sahin Ates, Yusuf Yagci, Cemil Dizman, Lokman Torun, Binnur Aydogan, Baris KiskanAbstract:Abstract Polysulfones with benzoxazine end groups (PSU-B-a) were obtained using monomer synthesis method from the phenol terminated Polysulfone (PSU-OH), aniline and paraformaldehyde as starting materials. For this purpose, the precursor PSU-OHs with different molecular weights were prepared by condensation of bisphenol-A and bis(p-chlorophenyl) sulfone in presence of potassium carbonate. The structure of the polymers before and after functionalization was confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR). Thermally activated crosslinking behavior of these polymers was investigated by differential scanning calorimetry (DSC). Thermal and tensile properties of the crosslinked polymers obtained from PSU-B-a alone or with low molar mass benzoxazine (P-a) were studied by thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA).
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synthesis characterization and photoinduced curing of Polysulfones with meth acrylate functionalities
Beilstein Journal of Organic Chemistry, 2010Co-Authors: Cemil Dizman, Sahin Ates, Lokman Torun, Yusuf YagciAbstract:The UV-curable telechelic Polysulfones with (meth)acrylate functionalities were synthesized by condensation polymerization and subsequent esterification. The final polymers and intermediates at various stages were characterized by 1H NMR, FT-ATR, and GPC. The oligomeric films prepared from the appropriate solutions containing these telechelics and 2,2-dimethoxy-2phenylacetophenone (DMPA) as the photoinitiator undergo rapid polymerization upon irradiation forming insoluble networks. The photo-curing behavior was investigated by photo-DSC and the effects of the molecular weight of the Polysulfone precursor and type of functionality on the rate of polymerization and conversion were evaluated. Thermal properties of the photochemically cured films were studied by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA).
Gilles P. Robertson - One of the best experts on this subject based on the ideXlab platform.
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Polysulfones with Phenylalanine Derivatives as Chiral Selectors – Membranes for Chiral Separation
2016Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. GuiverAbstract:Abstract: Polysulfone with a derivative of phenylalanyl residue as a chiral selector (PSf-Ac-D-Phe or PSf-Ac-L-Phe) were prepared by polymer reaction of benzylamine-modified Polysulfones with N--acetyl-D-phenylalanine or N--acetyl-L-phenylalanine. Both Polysulfones having a chiral selector gave durable self-standing membranes. The specific rotations of those polymers revealed that the chiral selectors were successfully introduced into the Polysulfone. PSf-Ac-D-Phe membrane incorporated L-Glu in preference to D-Glu and vice versa. The chiral separation ability was studied by applying a concentration gradient as a driving force for membrane transport. Permselectivities for those two types of membrane reflected their adsorption selectivities. PSf-Ac-D-Phe membrane selectively transported L-Glu and vice versa. Predicted permselectivities by adopting membrane resistance coincided with the observed ones
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Polysulfones with phenylalanine derivatives as chiral selectors membranes for chiral separation
Journal of Membrane and Separation Technology, 2012Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. GuiverAbstract:Polysulfone with a derivative of phenylalanyl residue as a chiral selector (PSf-Ac-D-Phe or PSf-Ac-L-Phe) were prepared by polymer reaction of benzylamine-modified Polysulfones with N-a-acetyl-D-phenylalanine or N-a-acetyl-L-phenylalanine. Both Polysulfones having a chiral selector gave durable self-standing membranes. The specific rotations of those polymers revealed that the chiral selectors were successfully introduced into the Polysulfone. PSf-Ac-D-Phe membrane incorporated L-Glu in preference to D-Glu and vice versa . The chiral separation ability was studied by applying a concentration gradient as a driving force for membrane transport. Permselectivities for those two types of membrane reflected their adsorption selectivities. PSf-Ac-D-Phe membrane selectively transported L-Glu and vice versa . Predicted permselectivities by adopting membrane resistance coincided with the observed ones.
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electrospun nanofiber membranes from Polysulfones with chiral selector aimed for optical resolution
European Polymer Journal, 2012Co-Authors: Hiroaki Mizushima, Masakazu Yoshikawa, Michael D. Guiver, Gilles P. RobertsonAbstract:Abstract Polysulfones with three types of alanyl residue, such as N -α-acetylalanine (Ac-Ala-OH), N -α-benzoylalanine (Bzo-Ala-OH), and N -α-benzyloxycarbonylalanine (Z-Ala-OH), as chiral selectors were prepared by polymer reaction. The resulting modified Polysulfones showed chiroptical properties, indicating that the chiral selector residues were successfully introduced into the Polysulfone. Nanofiber membranes prepared from the polymeric materials showed adsorption selectivity toward mixtures of racemic Glu, which were adopted as model racemates. Flux values for the nanofiber membranes were enhanced two to three orders of magnitude in comparison with the corresponding typical membranes, but without reduction in permselectivity. In the present study, it is shown that nanofiber is a suitable membrane form not only for molecularly imprinted membranes, but it exhibits enhanced throughput in comparison with typical dense membranes without concurrent reduction in permselectivity.
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modified Polysulfones vi preparation of polymer membrane materials containing benzimine and benzylamine groups as precursors for molecularly imprinted sensor devices
Journal of Polymer Science Part A, 2003Co-Authors: Gilles P. Robertson, Michael D. Guiver, Francois Bilodeau, Masakazu YoshikawaAbstract:A modified Polysulfone containing benzylamine groups was synthesized as a reactive membrane material. Polysulfone was activated at the ortho-sulfone site by direct lithiation with n-butyllithium, and the resulting lithiated Polysulfone was then reacted with benzonitrile; this yielded a polymer with pendant benzimine groups. The structure was confirmed by NMR and IR spectroscopy and by the transformation of imine to ketone by acid hydrolysis. The polymeric benzimine was also reduced to benzylamine with sodium cyanoborohydride in an acidic medium. The structure and degree of substitution of both benzylamine derivatives were determined by NMR and IR spectroscopy. The modified Polysulfone containing benzylamine groups initiated the polymerization of N-carboxyanhydride of γ-benzyl-L-glutamate [Glu(OBzl)–NCA]. The side-chain oligopeptide of Glu(OBzl)–NCA attached to Polysulfone was converted into molecular recognition sites. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1316–1329, 2003
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gas transport in modified Polysulfones with trimethylsilyl groups effect of substitution site
Journal of Membrane Science, 2003Co-Authors: Kwi Jong Lee, Michael D. Guiver, Gilles P. Robertson, Ying Dai, Yong Soo Kang, Jae Young Jho, Jongok WonAbstract:Trimethylsilyl (TMS) groups were chemically introduced on to the phenylene group of bisphenol-A Polysulfone (PSf) at sites ortho to ether (EM3) or to sulfone (SM3) linkages. Gas permeabilities increased by substitution of TMS and especially oxygen permeability increased from 1.1 barrer for PSf to 4.2 barrer for SM3 and to 7.1 barrer for EM3. Perm-selectivity of oxygen to nitrogen decreased from 5.8 to 5.5 and therefore substitution of TMS on Polysulfone resulted in improved gas transport properties. In addition, it was found that EM3 is more effective in enhancing the gas transport properties than SM3. In order to interpret the effect substitution site on gas transport, d-spacing was investigated in terms of interchain packing. Furthermore, the effect of substitution site on chain motion was investigated through dynamic mechanical analyzer (DMA), dielectric analyzer (DEA), and solid-state NMR. DMA and DEA experiments showed that motions of unsubstituted phenylene and sulfonyl linkage are much more hindered in SM3 than in EM3. NMR experiments showed that motion of TMS is more mobile in EM3 than in SM3. These results revealed that chain motions of SM3 are more hindered than those of EM3 and substitution site affects chain motions. Therefore, we can conclude that these changes in chain motion also gas transport in modified Polysulfones with silyl side group.
