The Experts below are selected from a list of 23799 Experts worldwide ranked by ideXlab platform

Michael D. Guiver - One of the best experts on this subject based on the ideXlab platform.

  • Polysulfones with Phenylalanine Derivatives as Chiral Selectors – Membranes for Chiral Separation
    2016
    Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. Guiver
    Abstract:

    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

  • Polysulfones with phenylalanine derivatives as chiral selectors membranes for chiral separation
    Journal of Membrane and Separation Technology, 2012
    Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. Guiver
    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-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.

  • electrospun nanofiber membranes from Polysulfones with chiral selector aimed for optical resolution
    European Polymer Journal, 2012
    Co-Authors: Hiroaki Mizushima, Masakazu Yoshikawa, Michael D. Guiver, Gilles P. Robertson
    Abstract:

    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.

  • gas transport in modified Polysulfones with trimethylsilyl groups effect of substitution site
    Journal of Membrane Science, 2003
    Co-Authors: Kwi Jong Lee, Michael D. Guiver, Gilles P. Robertson, Ying Dai, Yong Soo Kang, Jae Young Jho, Jongok Won
    Abstract:

    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.

  • modified Polysulfones 5 synthesis and characterization of tetramethyl Polysulfones containing trimethylsilyl groups and their gas transport properties
    Polymer, 2002
    Co-Authors: Ying Dai, Michael D. Guiver, Gilles P. Robertson, Francois Bilodeau, Yong Soo Kang, Kwi Jong Lee, Jae Young Jho, Jongok Won
    Abstract:

    Polysulfones with rigid backbone structures and silyl-containing substituents were prepared as membrane materials with potentially enhanced gas transport properties. Tetramethylbisphenol-A polysulfone (TMPSf) and tetramethylbiphenol polysulfone (TMPPSf) were made by polycondensation then post-modified to introduce trimethylsilyl (TMS) groups by bromination and lithiation methodology. Substitution of high levels of TMS groups at the ortho-sulfone sites was achieved using direct lithiation followed by addition of a trimethylsilane electrophile. In an approach to increase the overall TMS substitution level as well as introduce these groups on the bisphenol segment, both TMPSf and TMPPSf were cleanly brominated to a degree of substitution (DS) of 2.0 for bromine. While the subsequent lithium–halogen exchange and reaction with TMS electrophile did not give high regioselectivity because of steric hindrance, the overall DS of TMS in the polymers was increased when excess n-butyllithium was used to activate both brominated and ortho-sulfone sites. The polymer structures were characterized by NMR spectroscopy. Their thermal properties as well as O2, N2, CO2 and CH4 gas transport properties were measured. Polymers with a high DS of TMS had very high CO2 and O2 permeabilities and good permselectivities from N2. The permselectivities of CO2/N2 were at or close to the Robeson upper-bound performance line [J. Membr. Sci. 62 (1991) 165].

Patric Jannasch - One of the best experts on this subject based on the ideXlab platform.

  • proton conducting aromatic polymers carrying hypersulfonated side chains for fuel cell applications
    Advanced Functional Materials, 2007
    Co-Authors: Benoit Lafitte, Patric Jannasch
    Abstract:

    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.

  • polysulfone ionomers for proton conducting fuel cell membranes 2 sulfophenylated Polysulfones and polyphenylsulfones
    Electrochimica Acta, 2005
    Co-Authors: Lina Karlsson, Patric Jannasch
    Abstract:

    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.

  • polysulfone ionomers for proton conducting fuel cell membranes sulfoalkylated Polysulfones
    Journal of Membrane Science, 2004
    Co-Authors: Lina Karlsson, Patric Jannasch
    Abstract:

    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)

  • Phosphonation of Polysulfones via lithiation and reaction with chlorophosphonic acid esters
    Journal of Polymer Science Part A: Polymer Chemistry, 2004
    Co-Authors: Benoit Lafitte, Patric Jannasch
    Abstract:

    A noncatalytic route for the phosphonation of Polysulfones was established in which lithiated sites on Polysulfones were reacted with an excess of chlorophosphonic acid esters through an SNP(V) mechanism. Both the bisphenol A and biphenyl sulfone segments of the polysulfone main chain were modified according to whether brominated polysulfone or pristine polysulfone was used. Up to 50% of the repeating units of the Polysulfones were modified by a careful selection of reaction parameters to avoid crosslinking. The phosphonated Polysulfones in their acid form showed high thermal stability with decomposition temperatures of approximately 350 C under nitrogen. Polysulfones with phosphonated bisphenol A segments showed good membrane-forming properties and are candidates for components in ionomer composite membranes for fuel cells. (Less)

  • Sulfophenylation of Polysulfones for Proton‐Conducting Fuel Cell Membranes
    Macromolecular Rapid Communications, 2002
    Co-Authors: Benoit Lafitte, Lina Karlsson, Patric Jannasch
    Abstract:

    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.

Ecaterina Avram - One of the best experts on this subject based on the ideXlab platform.

  • ionic transport processes in polymer mixture solutions based on quaternized Polysulfones
    The Journal of Chemical Thermodynamics, 2017
    Co-Authors: Anca Filimon, Adina Maria Dobos, Ecaterina Avram
    Abstract:

    Abstract High-performance ionic Polysulfones for advanced applications, derived from chloromethylated Polysulfones and tertiary amines, i.e., N,N-dimethylbutylamine, were synthesized by a two-step polycondensation reaction and analyzed by the conductometric method. Ionic transport processes developed in ternary systems consisting of an ionic polymer (quaternized polysulfone), a neutral polymer (cellulose acetate phthalate or polyvinyl alcohol), and a dipolar aprotic solvent (N-methyl-2-pyrrolidone) offer information concerning the combined action of the electrostatic repulsive interactions, of associations which can take place inside the same polymer chain (intra-molecular interactions) or between different chains (inter-molecular interactions). Conductometric experimental data for polyelectrolyte/neutral polymer/solvent ternary systems are macroscopic results that can be interpreted on the basis of these interactions, and are reported as a function of the factors controlling the transport properties, such as the polymer solution concentration, polymer mixture composition, charge density, and polarity of the solvent. Additionally, the validity of Manning’s theory was applied to the studied ternary systems and important discrepancies between the theory and experiment were observed.

  • blends based on ionic Polysulfones with improved conformational and microstructural characteristics perspectives for biomedical applications
    Composites Part B-engineering, 2016
    Co-Authors: Anca Filimon, Raluca Marinica Albu, Iuliana Stoica, Ecaterina Avram
    Abstract:

    Ionic Polysulfones have received widespread attention for their promising roles as ionic exchange membranes, antibacterial coatings, and dialysis membranes. Therefore, the blends of the quaternized polysulfone with a tunable content of polyvinyl alcohol were obtained to create new materials that can modulate the membrane properties. The rheological response of quaternized polysulfone/polyvinyl alcohol in N-methyl-2-pyrrolidone blends to the structural peculiarity of polymers from the blend, composition of polymer mixtures, as well as the types of interactions was investigated. Rheological behavior of the complex system, described by the non-linear flow curve, indicates the plasticizer effect of polyvinyl alcohol to quaternized polysulfone solutions, in order to facilitate the subsequently preparation of the bioactive membranes. Additionally, the specific microarchitecture of the blends, determined using atomic force microscopy, represents an excellent porous membrane scaffold with expected future developments in the biomedical fields.

  • surface and interface properties of functionalized Polysulfones cell material interaction and antimicrobial activity
    Polymer Engineering and Science, 2015
    Co-Authors: Anca Filimon, Ecaterina Avram, Simona Dunca
    Abstract:

    Quaternized Polysulfones with different ionic chlorine content tested for biomedical applications were obtained by quaternization reaction of chloromethylated Polysulfones with N,N-dimethylethanolamine. The relationship between the different physical and chemical characteristics of these polymers and their biocompatible and antimicrobial properties was established for maximizing the selectivity and performance of these materials for biomedical applications. Therefore, topographic reorganization of the polysulfonic films induced by the type of nonsolvent in casting solutions of polymer significantly influences films morphology, depending on the charge density of polyelectrolytes, the hydrophilic/hydrophobic characteristics, as well as on the history of the formed films. Furthermore, the study of the adhesion of red blood cells and cohesion of platelets on the surface of quaternized polysulfone films, as well as analysis of antibacterial activity, using Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 microorganisms, contribute to extending the possible applications of quaternized Polysulfones as semipermeable membranes in biomedical domains. POLYM. ENG. SCI., 55:2184–2194, 2015. © 2015 Society of Plastics Engineers

  • surface and interface properties of functionalized Polysulfones cell material interaction and antimicrobial activity
    Polymer Engineering and Science, 2015
    Co-Authors: Anca Filimon, Ecaterina Avram, Simona Dunca
    Abstract:

    Quaternized Polysulfones with different ionic chlorine content tested for biomedical applications were obtained by quaternization reaction of chloromethylated Polysulfones with N,N-dimethylethanolamine. The relationship between the different physical and chemical characteristics of these polymers and their biocompatible and antimicrobial properties was established for maximizing the selectivity and performance of these materials for biomedical applications. Therefore, topographic reorganization of the polysulfonic films induced by the type of nonsolvent in casting solutions of polymer significantly influences films morphology, depending on the charge density of polyelectrolytes, the hydrophilic/hydrophobic characteristics, as well as on the history of the formed films. Furthermore, the study of the adhesion of red blood cells and cohesion of platelets on the surface of quaternized polysulfone films, as well as analysis of antibacterial activity, using Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 microorganisms, contribute to extending the possible applications of quaternized Polysulfones as semipermeable membranes in biomedical domains. POLYM. ENG. SCI., 55:2184–2194, 2015. © 2015 Society of Plastics Engineers

  • Surface and interface properties of functionalized Polysulfones: Cell‐material interaction and antimicrobial activity
    Polymer Engineering and Science, 2015
    Co-Authors: Anca Filimon, Ecaterina Avram, Simona Dunca
    Abstract:

    Quaternized Polysulfones with different ionic chlorine content tested for biomedical applications were obtained by quaternization reaction of chloromethylated Polysulfones with N,N-dimethylethanolamine. The relationship between the different physical and chemical characteristics of these polymers and their biocompatible and antimicrobial properties was established for maximizing the selectivity and performance of these materials for biomedical applications. Therefore, topographic reorganization of the polysulfonic films induced by the type of nonsolvent in casting solutions of polymer significantly influences films morphology, depending on the charge density of polyelectrolytes, the hydrophilic/hydrophobic characteristics, as well as on the history of the formed films. Furthermore, the study of the adhesion of red blood cells and cohesion of platelets on the surface of quaternized polysulfone films, as well as analysis of antibacterial activity, using Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 microorganisms, contribute to extending the possible applications of quaternized Polysulfones as semipermeable membranes in biomedical domains. POLYM. ENG. SCI., 55:2184–2194, 2015. © 2015 Society of Plastics Engineers

Gilles P. Robertson - One of the best experts on this subject based on the ideXlab platform.

  • Polysulfones with Phenylalanine Derivatives as Chiral Selectors – Membranes for Chiral Separation
    2016
    Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. Guiver
    Abstract:

    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

  • Polysulfones with phenylalanine derivatives as chiral selectors membranes for chiral separation
    Journal of Membrane and Separation Technology, 2012
    Co-Authors: Jun Isezaki, Masakazu Yoshikawa, Gilles P. Robertson, Michael D. Guiver
    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-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.

  • electrospun nanofiber membranes from Polysulfones with chiral selector aimed for optical resolution
    European Polymer Journal, 2012
    Co-Authors: Hiroaki Mizushima, Masakazu Yoshikawa, Michael D. Guiver, Gilles P. Robertson
    Abstract:

    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.

  • gas transport in modified Polysulfones with trimethylsilyl groups effect of substitution site
    Journal of Membrane Science, 2003
    Co-Authors: Kwi Jong Lee, Michael D. Guiver, Gilles P. Robertson, Ying Dai, Yong Soo Kang, Jae Young Jho, Jongok Won
    Abstract:

    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.

  • modified Polysulfones 5 synthesis and characterization of tetramethyl Polysulfones containing trimethylsilyl groups and their gas transport properties
    Polymer, 2002
    Co-Authors: Ying Dai, Michael D. Guiver, Gilles P. Robertson, Francois Bilodeau, Yong Soo Kang, Kwi Jong Lee, Jae Young Jho, Jongok Won
    Abstract:

    Polysulfones with rigid backbone structures and silyl-containing substituents were prepared as membrane materials with potentially enhanced gas transport properties. Tetramethylbisphenol-A polysulfone (TMPSf) and tetramethylbiphenol polysulfone (TMPPSf) were made by polycondensation then post-modified to introduce trimethylsilyl (TMS) groups by bromination and lithiation methodology. Substitution of high levels of TMS groups at the ortho-sulfone sites was achieved using direct lithiation followed by addition of a trimethylsilane electrophile. In an approach to increase the overall TMS substitution level as well as introduce these groups on the bisphenol segment, both TMPSf and TMPPSf were cleanly brominated to a degree of substitution (DS) of 2.0 for bromine. While the subsequent lithium–halogen exchange and reaction with TMS electrophile did not give high regioselectivity because of steric hindrance, the overall DS of TMS in the polymers was increased when excess n-butyllithium was used to activate both brominated and ortho-sulfone sites. The polymer structures were characterized by NMR spectroscopy. Their thermal properties as well as O2, N2, CO2 and CH4 gas transport properties were measured. Polymers with a high DS of TMS had very high CO2 and O2 permeabilities and good permselectivities from N2. The permselectivities of CO2/N2 were at or close to the Robeson upper-bound performance line [J. Membr. Sci. 62 (1991) 165].

Donald R Paul - One of the best experts on this subject based on the ideXlab platform.

  • Water sorption and transport in a series of Polysulfones
    Journal of Polymer Science Part B: Polymer Physics, 1996
    Co-Authors: K. A. Schult, Donald R Paul
    Abstract:

    Water sorption and transport properties for a series of Polysulfones are presented and interpreted in terms of the changes in the structure of the repeat unit compared to that of bisphenol A polysulfone. The differences between the sorption and diffusion of water and of permanent gases in these materials are also discussed. Water has the ability to interact with the polymer and with itself through hydrogen bonding in a way that permanent gases cannot. The equilibrium solubility of water in the polymer, unlike permanent gases, does not have a simple dependence on free volume but correlates more strongly with the frequency of hydrogen bonding sites on the polymer. Analysis of the sorption isotherms using the method of Zimm and Lundberg suggests that water molecules cluster in these Polysulfones to various extents. For each polysulfone except polyethersulfone, the water diffusion coefficient decreases with increasing activity, which also suggests water clustering. For most of these materials, the water diffusion coefficient is larger than that of bisphenol A polysulfone and is directly related to the polymer free volume. Water permeability in these materials broadly correlates with the polymer free volume, but a favorable water-polymer interaction can be an overriding factor. © 1996 John Wiley & Sons, Inc.

  • Gas transport properties of adamantane-based Polysulfones
    Polymer, 1995
    Co-Authors: M. R. Pixton, Donald R Paul
    Abstract:

    Abstract Gas transport of helium, hydrogen, oxygen, nitrogen, methane and carbon dioxide gases in 2,2-(4-hydroxy-phenyl) adamantane polysulfone and 1,3-(4-hydroxyphenyl)adamantane polysulfone has been measured. The adamantane-containing polymers have higher gas permeabilities in all cases and higher permselectivities in some cases compared with bisphenol A-based polysulfone (PSF). Oxygen solubility is higher for both adamantane-based Polysulfones, particularly for the 2,2-isomer, and the high oxygen solubility coefficients are entirely responsible for the higher oxygen permeabilities compared with PSF. The physical properties of these materials are similar to those of fluorence bisphenol polysolfone (FBPSF); however, the Tg of the 2,2-isomer is higher while that of the 1,3-isomer is lower.

  • effect of structural symmetry on gas transport properties of Polysulfones
    Macromolecules, 1992
    Co-Authors: C. L. Aitken, William J. Koros, Donald R Paul
    Abstract:

    The effects of structural symmetry of phenylene linkages and methyl group placement on the properties of Polysulfones have been investigated. Polysulfones with unsymmetric structures have lower gas permeability and higher selectivity coefficients than their symmetric counterparts. The Polysulfones with m-phenylene linkages or dimethyl substitutions to the bisphenol unit have lower glass transition temperatures, lower fractional free volumes, and higher sub-T g relaxation temperatures. The chains of the unsymmetric polymers are generally more efficiently packed and appear to have greater mobility constraints

  • Gas transport properties of biphenol Polysulfones
    Macromolecules, 1992
    Co-Authors: C. L. Aitken, William J. Koros, Donald R Paul
    Abstract:

    Gas sorption and transport properties at 35 o C are reported for the polysulfone based on 4,4'-biphenol (BIPSF) and corresponding Polysulfones with methyl ring substitutions, tetramethylbiphenol polysulfone (TMBIPSF) and hexamethylbiphenol polysulfone (HMBIPSF). Comparisons are made to bisphenol A polysulfone (PSF) and tetramethylbisphenol A polysulfone (TMPSF). BIPSF and PSF have very similar transport characteristics. This is attributed to the similar packing behavior of these polymers. Permeability values are discussed in terms of chain packing, fractional free volume and sub-T g relaxation behavior