The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Michael D. Guiver - One of the best experts on this subject based on the ideXlab platform.
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poly arylene ether sulfone proton exchange membranes with flexible acid side chains
Journal of Membrane Science, 2012Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Michael D. Guiver, So Young Lee, Young Moo LeeAbstract:Abstract New monomers containing two or four pendent methoxyphenyl Groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxyphenyl Groups (2-MPAES- xx and 4-MPAES- xx ) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy Group to the Reactive Hydroxyl Group, the respective side chain-type sulfonated copolymers (2-SPAES- xx and 4-SPAES- xx ) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl Groups had high proton conductivities in the range of 0.108–0.258 S/cm for 2-SPAES- xx and 0.135–0.194 S/cm for 4-SPAES- xx at 80 °C, respectively. The methanol permeabilities of these membranes were in the range of 1.59 × 10 −7 –4.69 × 10 −7 cm 2 /s, which is much lower than Nafion ® (15.5 × 10 −7 cm 2 /s). 2-SPAES- xx and 4-SPAES- xx display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl Groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications.
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fluorene based poly arylene ether sulfone s containing clustered flexible pendant sulfonic acids as proton exchange membranes
Macromolecules, 2011Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Nanwen Li, Michael D. GuiverAbstract:A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy Groups (MPAES). After converting the methoxy Group to the Reactive Hydroxyl Group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10–7 cm2/s, which is lower than Nafi...
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comb shaped poly arylene ether sulfone s as proton exchange membranes
Macromolecules, 2008Co-Authors: Dae Sik Kim, Gilles P Robertson, Michael D. GuiverAbstract:A new sulfonated side-chain grafting unit containing two or four sulfonic acid Groups was synthesized using sulfonated 4-fluorobenzophenone (FBP) and 1,1-bis(4-hydroxyphenyl)-1,4-((4-fluorophenyl)thio)phenyl-2,2,2-trifluoroethane (3FBPT). A conventional aromatic nucleophilic substitution (SNAr) was used for copolymerization of poly(arylene ether sulfone) containing a methoxy Group. After converting the methoxy Group to the Reactive Hydroxyl Group, this functionalized copolymer was reacted to graft the sulfonated side chains to make the comb-shaped sulfonated poly(arylene ether sulfone) copolymers. All the polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), the water uptake, and proton and methanol transport for fuel cell applications. These comb-shaped sulfonated polymers had good properties as polyelectrolyte membrane materials. The comb-shaped copolymers with two or four sulfonic acid Groups show high proton conductivity in the range of 34−147 and 63−125 mS/cm, respectively. The met...
Chenyi Wang - One of the best experts on this subject based on the ideXlab platform.
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poly arylene ether sulfone proton exchange membranes with flexible acid side chains
Journal of Membrane Science, 2012Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Michael D. Guiver, So Young Lee, Young Moo LeeAbstract:Abstract New monomers containing two or four pendent methoxyphenyl Groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxyphenyl Groups (2-MPAES- xx and 4-MPAES- xx ) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy Group to the Reactive Hydroxyl Group, the respective side chain-type sulfonated copolymers (2-SPAES- xx and 4-SPAES- xx ) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl Groups had high proton conductivities in the range of 0.108–0.258 S/cm for 2-SPAES- xx and 0.135–0.194 S/cm for 4-SPAES- xx at 80 °C, respectively. The methanol permeabilities of these membranes were in the range of 1.59 × 10 −7 –4.69 × 10 −7 cm 2 /s, which is much lower than Nafion ® (15.5 × 10 −7 cm 2 /s). 2-SPAES- xx and 4-SPAES- xx display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl Groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications.
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fluorene based poly arylene ether sulfone s containing clustered flexible pendant sulfonic acids as proton exchange membranes
Macromolecules, 2011Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Nanwen Li, Michael D. GuiverAbstract:A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy Groups (MPAES). After converting the methoxy Group to the Reactive Hydroxyl Group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10–7 cm2/s, which is lower than Nafi...
María Del Carmen Garrigós - One of the best experts on this subject based on the ideXlab platform.
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Controlled Release, Disintegration, Antioxidant, and Antimicrobial Properties of Poly (Lactic Acid)/Thymol/Nanoclay Composites.
Polymers, 2020Co-Authors: Marina Ramos, Elena Fortunati, Ana Beltrán, Mercedes Ana Peltzer, Francesco Cristofaro, Livia Visai, Artur J.m. Valente, Alfonso Jiménez, Jose Maria Kenny, María Del Carmen GarrigósAbstract:Nano-biocomposite films based on poly (lactic acid) (PLA) were prepared by adding thymol (8 wt.%) and a commercial montmorillonite (D43B) at different concentrations (2.5 and 5 wt.%). The antioxidant, antimicrobial, and disintegration properties of all films were determined. A kinetic study was carried out to evaluate the thymol release from the polymer matrix into ethanol 10% (v/v) as food simulant. The nanostructured networks formed in binary and ternary systems were of interest in controlling the release of thymol into the food simulant. The results indicated that the diffusion of thymol through the PLA matrix was influenced by the presence of the nanoclay. Disintegration tests demonstrated that the incorporation of both additives promoted the breakdown of the polymer matrix due to the presence of the Reactive Hydroxyl Group in the thymol structure and ammonium Groups in D43B. Active films containing thymol and D43B efficiently enhanced the antioxidant activity (inhibition values higher than 77%) of the nano-biocomposites. Finally, the addition of 8 wt.% thymol and 2.5 wt.% D43B significantly increased the antibacterial activity against Escherichia coli and Staphylococcus aureus 8325-4, resulting in a clear advantage to improve the shelf-life of perishable packaged food.
Na Rae Kang - One of the best experts on this subject based on the ideXlab platform.
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poly arylene ether sulfone proton exchange membranes with flexible acid side chains
Journal of Membrane Science, 2012Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Michael D. Guiver, So Young Lee, Young Moo LeeAbstract:Abstract New monomers containing two or four pendent methoxyphenyl Groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxyphenyl Groups (2-MPAES- xx and 4-MPAES- xx ) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy Group to the Reactive Hydroxyl Group, the respective side chain-type sulfonated copolymers (2-SPAES- xx and 4-SPAES- xx ) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl Groups had high proton conductivities in the range of 0.108–0.258 S/cm for 2-SPAES- xx and 0.135–0.194 S/cm for 4-SPAES- xx at 80 °C, respectively. The methanol permeabilities of these membranes were in the range of 1.59 × 10 −7 –4.69 × 10 −7 cm 2 /s, which is much lower than Nafion ® (15.5 × 10 −7 cm 2 /s). 2-SPAES- xx and 4-SPAES- xx display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl Groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications.
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fluorene based poly arylene ether sulfone s containing clustered flexible pendant sulfonic acids as proton exchange membranes
Macromolecules, 2011Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Nanwen Li, Michael D. GuiverAbstract:A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy Groups (MPAES). After converting the methoxy Group to the Reactive Hydroxyl Group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10–7 cm2/s, which is lower than Nafi...
Dong-won Shin - One of the best experts on this subject based on the ideXlab platform.
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poly arylene ether sulfone proton exchange membranes with flexible acid side chains
Journal of Membrane Science, 2012Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Michael D. Guiver, So Young Lee, Young Moo LeeAbstract:Abstract New monomers containing two or four pendent methoxyphenyl Groups were synthesized by bromination of bis(4-fluorophenyl)sulfone, followed by Suzuki coupling with 4-methoxybenzeneboronic acid. Copoly(arylene ether sulfone)s containing methoxyphenyl Groups (2-MPAES- xx and 4-MPAES- xx ) based on the corresponding monomers were prepared by aromatic nucleophilic substitution (SNAr) polycondensation. After demethylation of the methoxy Group to the Reactive Hydroxyl Group, the respective side chain-type sulfonated copolymers (2-SPAES- xx and 4-SPAES- xx ) were obtained by sulfobutylation. Flexible and tough membranes having good mechanical strength were obtained by solution casting of all copolymers. The sulfonated copolymers with two or four pendent sulfobutoxyphenyl Groups had high proton conductivities in the range of 0.108–0.258 S/cm for 2-SPAES- xx and 0.135–0.194 S/cm for 4-SPAES- xx at 80 °C, respectively. The methanol permeabilities of these membranes were in the range of 1.59 × 10 −7 –4.69 × 10 −7 cm 2 /s, which is much lower than Nafion ® (15.5 × 10 −7 cm 2 /s). 2-SPAES- xx and 4-SPAES- xx display comparatively better balance between proton conductivity and water swelling than the analogous poly(arylene ether sulfone)s containing pendent sulfophenyl Groups. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they have some of the requisite properties for proton exchange membranes in fuel cell applications.
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fluorene based poly arylene ether sulfone s containing clustered flexible pendant sulfonic acids as proton exchange membranes
Macromolecules, 2011Co-Authors: Chenyi Wang, Na Rae Kang, Dong-won Shin, Nanwen Li, Michael D. GuiverAbstract:A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy Groups (MPAES). After converting the methoxy Group to the Reactive Hydroxyl Group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10–7 cm2/s, which is lower than Nafi...
