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Michael A. Hickner - One of the best experts on this subject based on the ideXlab platform.

  • Spectroscopic Characterization of Sulfonate Charge Density in Ion-Containing Polymers.
    The journal of physical chemistry. B, 2017
    Co-Authors: Sarah B. Smedley, Tawanda J. Zimudzi, Ying Chang, Chulsung Bae, Michael A. Hickner
    Abstract:

    The charge density and hydrogen bonding with water of five different polymer membranes functionalized with various sulfonate side-chain chemistries were investigated using Fourier transform infrared (FTIR) techniques and density functional theory (DFT) calculations. The peak position of the OD stretch of dilute HOD absorbed into the sulfonated poly(sulfone) membranes was studied using FTIR to compare the charge density of the sulfonate headgroup across the different samples, which can ultimately be related to the acidity of the proton-form sulfonate moieties. The OD peak was deconvoluted to determine the percentage of headgroup-associated, intermediate, and bulk water. DFT modeling was used to calculate the charge density of each headgroup and visualize how the chemistry of the headgroup influenced the conformation of the side-chain tether. FTIR-determined OD peak positions and charge density calculations demonstrated that a perflurosulfonate containing a thioether linkage produced the most acidic sulfona...

  • Anion exchange membranes by bromination of tetramethylbiphenol-based poly(sulfone)s
    Polymer Chemistry, 2017
    Co-Authors: Jingling Yan, Liang Zhu, Brian L. Chaloux, Michael A. Hickner
    Abstract:

    Anion exchange membranes (AEM) with tunable properties were synthesized via bromination of poly(ether sulfone)s containing tetramethylbiphenol (TMBP) comonomers, followed by bromination, quaternization, and ion exchange. The bromination reactions of poly(ether sulfone)s containing TMBP and tetramethylbisphenol A (TMBA) comonomers were assessed in terms of the composition of the polymers and the molar equivalents of N-bromosuccinimide (NBS). Compared with TMBP-based polymers, TMBA-based poly(sulfone)s were more susceptible to degradation during bromination due to the degradation of the isopropylidene linkage in TMBA under radical conditions, resulting in a weight average molecular weight decrease of 31–43% after bromination. The decrease of molecular weights also became more pronounced when the equivalents of NBS was raised. Polydispersity after bromination increased for both TMBP- and TMBA-based polymers because of side reactions such as branching, crosslinking, and chain scission. For a given ion exchange capacity, the conductivity and water uptake of TMBP-based AEMs were lower than those of the TMBA-based samples, which can be attributed to the relatively rigid TMBP residue. AEMs in this study retained 40–62% of their original conductivity after degradation in 1 M NaOH solution at 90 °C for 500 hours.

  • FTIR Characterization of Water–Polymer Interactions in Superacid Polymers
    The journal of physical chemistry. B, 2013
    Co-Authors: Sarah Black, Chulsung Bae, Ying Chang, Michael A. Hickner
    Abstract:

    The OD stretch of dilute HOD in H2O absorbed in a series of sulfonated syndiotactic poly(styrene) and sulfonated poly(sulfone) membranes was studied using FTIR spectroscopy to measure how the chara...

  • Synthesis and structure–property relationships of poly(sulfone)s for anion exchange membranes
    Journal of Polymer Science Part B: Polymer Physics, 2013
    Co-Authors: Jingling Yan, Hunter D. Moore, Michael R. Hibbs, Michael A. Hickner
    Abstract:

    Membranes based on cationic polymers that conduct anions are important for enabling alkaline membrane fuel cells and other solid-state electrochemical devices that operate at high pH. Anion exchange membranes with poly(arylene ether sulfone) backbones are demonstrated by two routes: chloromethylation of commercially available poly(sulfone)s or radical bromination of benzylmethyl moieties in poly(sulfone)s containing tetramethylbisphenol A monomer residues. Polymers with tethered trimethylbenzyl ammonium moieties resulted from conversion of the halomethyl groups by quaternization with trimethyl amine. The water uptake of the chloromethylated polymers was dependent on the type of poly(sulfone) backbone for a given IEC. Bisphenol A-based Udel (R) poly(sulfone) membranes swelled in water to a large extent while membranes from biphenol-based Radel (R) poly(sulfone), a stiffer backbone than Udel, only showed moderate water uptake. The water uptake of cationic poly(sulfone)s was further reduced by synthesizing tetramethylbisphenol A and 4,4-biphenol-containing poly(sulfone) copolymers where the ionic groups were clustered on the tetramethylbisphenol A residues. The conductivity of all samples scaled with the bulk water uptake. The hydration number of the membranes could be increased by casting membranes from the ionic form polymers versus converting the halomethyl form cast polymers to ionic form in the solid state. (c) 2013 Wiley Periodicals, Inc. J. more » Polym. Sci., Part B: Polym. Phys. 2013, 51, 1790-1798, 2013 « less

  • synthesis of highly sulfonated poly arylene ether sulfone random statistical copolymers via direct polymerization
    Macromolecular Symposia, 2001
    Co-Authors: Feng Wang, Michael A. Hickner, William Harrison, Jeffrey B Mecham, Thomas A Zawodzinski, James E Mcgrath
    Abstract:

    Novel biphenol-based wholly aromatic poly (arylene ether sulfones) containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of disodium 3,3'-disulfonate-4,4'-dichlorodiphenyl sulfone (SDCDPS), 4,4'-dichlorodiphenylsulfone (DCDPS) and biphenol. Copolymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at 190°C in the presence of anhydrous potassium carbonate. Tough membranes were successfully cast from the control and the copolymers, which had a SDCDPS/DCDPS mole ratio of either 40:60 or 60:40 using N,N-dimethylactamide; the 100% SDCDPS homopolymer was water soluble. Short-term aging (30 min) indicates that the desired acid form membranes are stable to 220°C in air and conductivity values at 25°C of 0.110 (40%) and 0.170 S/cm (60%) were measured, which are comparable to or higher than the state-of-the art fluorinated copolymer Nafion 1135 control. The new copolymers, which contain ion conductivity sites on deactivated rings, are candidates as new polymeric electrolyte materials for proton exchange membrane (PEM) fuel cells. Further research comparing their membrane behavior to post-sulfonated systems is in progress.

Shahram Mehdipour-ataei - One of the best experts on this subject based on the ideXlab platform.

  • Effect of sepiolite nanoparticles on the properties of novel poly(sulfone ether imide)
    Polymers for Advanced Technologies, 2016
    Co-Authors: Farideh Abbasi, Shahram Mehdipour-ataei, Zahra Tabatabaei-yazdi, Samal Babanzadeh, Ebrahim Abouzari-lotf
    Abstract:

    A new poly(sulfone ether imide) was prepared, and related nanocomposites were produced through introduction of sepiolite nanoparticles into the matrix of polymer. Inherent viscosity, thermal and mechanical features of pristine poly(sulfone ether imide), and nanocomposite samples were evaluated and compared. The crystallinity was also investigated. Dispersion and distribution behaviors of nanocomposite samples and cross-sectional morphology of nanocomposite films were also studied. Also, the optimized amounts of sepiolite nanoparticles in the matrix of polymer were determined by microscopic techniques (scanning electron microscope and transmission electron microscope). By introduction of 3 wt% of sepiolite, superior thermal and mechanical properties were observed. Copyright © 2016 John Wiley & Sons, Ltd.

  • Novel type of highly soluble and thermally stable poly(sulfone ether imide)s
    Designed Monomers and Polymers, 2015
    Co-Authors: Farideh Abbasi, Shahram Mehdipour-ataei, Saeed Khademinejad
    Abstract:

    A sulfone ether diamine was synthesized by three-step reactions. Firstly, 4-(4-nitrophenoxy) phenol was synthesized via nucleophilic substitution reaction of 1-fluoro-4-nitrobenzene with hydroquinone in the presence of K2CO3 in NMP. In the second step, 4-(4-nitrophenoxy) phenol was reduced to 4-(4-aminophenoxy) phenol by Pd/activated carbon catalyst in ethanolic hydrazine hydrate. Finally, 4-(4-aminophenoxy) phenol was reacted with 4,4′-dichlorodiphenyl sulfone (with 2:1 M ratio) to produce the sulfone ether diamine. Then three different kinds of poly(sulfone ether imide)s were prepared by solution polycondensation of synthesized diamine with commercially available aromatic dianhydrides including pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride. The structure of synthesized compounds, monomers, and prepared polymers was characterized using 1H NMR and FT-IR spectroscopy and also elemental analysis method. Thermal behavior and stability, so...

  • Synthesis and characterization of novel thermally stable poly(ether-amide)s containing dinaphthosulfone units in the main chain
    E-polymers, 2011
    Co-Authors: Abbas Shockravi, Shahram Mehdipour-ataei, Shaghayegh Naghdi
    Abstract:

    A New type of sulfone (4) containing 1,1´-thiobis(2- hydroxynaphthalene) diacid as a monomer was synthesized from the reaction of 2-hydroxynaphthalene (1) and sulfur dichloride, followed by reaction with methylchloroactate to obtain diester (2). Oxidation of this product in the presence of hydrogen peroxide followed by basic hydrolysis led to corresponding sulfone diacid (4) in good yield. Six organic-soluble poly(ether-amide)s bearing sulfone groups were synthesized via direct polycondensation of diacid (4) with commercially available aromatic diamines in the presence of calcium chloride as dehydrating agent. The resulting polyamides had inherent viscosity ranging from 0.38 to 0.46 dLg -1 at concentration of 0.5 gdL -1

  • Novel thermally stable poly(sulfone ether ester imide)s
    European Polymer Journal, 2005
    Co-Authors: Shahram Mehdipour-ataei
    Abstract:

    A novel sulfone ether ester diamine was prepared by a three-step method. Reaction of 1,5-dihydroxy naphthalene with 4-nitrobenzoyl chloride afforded 5-hydroxy-1-naphthyl-4-nitrobenzoate. Reduction of nitro group by iron powder and HCl resulted in preparation of 5-hydroxyl-1-naphthyl-4-aminobenzoate. Reaction of this compound (two moles) with bis (4-chlorophenyl) sulfone led to preparation of a novel sulfone ether ester diamine. Three novel aromatic poly(sulfone ether ester imide)s were synthesized by polycondensation reactions of the prepared diamine with aromatic dianhydrides. Conventional methods were used to characterize the structure of the monomer and polymers. Physical properties of the polymers were also studied. The polyimides showed high thermal stability.

  • Novel thermally stable polyimides based on flexible diamine: synthesis, characterization, and properties
    European Polymer Journal, 2004
    Co-Authors: Shahram Mehdipour-ataei, Yaghoub Sarrafi, Mehdi Hatami
    Abstract:

    A novel diamine with built-in sulfone, ether, and amide structure was prepared via three-step reactions. Nucleophilic reaction of 4-aminophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide led to preparation of N-(4-hydroxy phenyl)-4-nitrobenzamide (HPNB). The nitro group of this compound was reduced with hydrazine and Pd/C to afford 4-amino-N-(4-hydroxy phenyl)benzamide (AHPB). Two moles of AHPB were reacted with bis-(4-chloro phenyl)sulfone to provide a novel sulfone ether amide diamine (SEAD). All the prepared compounds were characterized by common spectroscopic methods. The prepared diamine (SEAD) used to prepare related polyimides by reaction with different aromatic dianhydrides. The obtained poly(sulfone ether amide imide)s were characterized and their properties were studied.

James E Mcgrath - One of the best experts on this subject based on the ideXlab platform.

  • hydrophilic hydrophobic multiblock copolymers based on poly arylene ether sulfone via low temperature coupling reactions for proton exchange membrane fuel cells
    Polymer, 2008
    Co-Authors: Haeseung Lee, Abhishek Roy, Ozma Lane, Stuart Dunn, James E Mcgrath
    Abstract:

    Abstract Two series of multiblock copolymers based on poly(arylene ether sulfone)s were developed and evaluated for use as proton exchange membranes (PEMs). The multiblock copolymers were synthesized by a coupling reaction between phenoxide terminated fully disulfonated poly(arylene ether sulfone) (BPSH100) and decafluorobiphenyl (DFBP) or hexafluorobenzene (HFB) end-capped unsulfonated poly(arylene ether sulfone) (BPS0) as hydrophilic and hydrophobic blocks, respectively. The highly reactive nature of DFBP and HFB allowed the coupling reactions to be accomplished under mild reaction conditions (e.g.,

  • hydrocarbon and partially fluorinated sulfonated copolymer blends as functional membranes for proton exchange membrane fuel cells
    American Chemical Society National Meeting, 2007
    Co-Authors: Natalie Y Arnett, Ozma Lane, William Harrison, Anand S Badami, Frank Cromer, Limin Dong, James E Mcgrath
    Abstract:

    Polymer blending is recognized as a valuable technique used to modify and improve the mechanical, thermal, and surface properties of two different polymers or copolymers. This paper investigated the solution properties and membrane properties of a biphenol-based disulfonated poly (arylene ether sulfone) random copolymer (BPS-35) with hexafluoroisopropylidene bisphenol based sulfonated poly (arylene ether sulfone) copolymers (6FSH) and an unsulfonated biphenol-based poly (arylene ether sulfone)s. The development of blended membranes with desirable surface characteristics, reduced water swelling and similar proton conductivity is presented. Polymer blends were prepared both in the sodium salt and acid forms from dimethylacetamide (DMAc). Water uptake, specific conductivity, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angles were used to characterize the blended films. Surface enrichment of the fluorinated component is illustrated by an significant increase in the water-surface contact angle was observed when 10 wt.% 6FBPA-00 (106°) was added to BPS 35 (80°). Water weight gain was reduced by a factor of 2.

  • poly arylene ether sulfone copolymers and related systems from disulfonated monomer building blocks synthesis characterization and performance a topical review
    Fuel Cells, 2005
    Co-Authors: William Harriso, Michael A Hickne, Yu Seung Kim, James E Mcgrath
    Abstract:

    Research and development efforts have been focussed over the last five years towards the preparation of new, but potentially commercially viable low-cost copolymers for use as proton exchange membrane for fuel cell and other membrane applications. Our primary efforts centered on the direct synthesis of disulfonated copolymers via step-polycondensation methods. These novel series of disulfonated copolymers include optionally fluorinated poly(arylene ethers), poly(thioethers), polyimides, polybenzimidazoles, and polybenzoxazoles, as well as multiblock copolymer systems. The first generation of alternative proton exchange membranes (PEMs) has focused on wholly aromatic, disulfonated poly(arylene ether sulfone) random copolymers. Detailed herein are the development and current state of these disulfonated poly(arylene ether sulfone) copolymers and their fuel cell performance in both hydrogen-air PEMFCs and direct methanol fuel cells (DMFC).

  • synthesis of highly sulfonated poly arylene ether sulfone random statistical copolymers via direct polymerization
    Macromolecular Symposia, 2001
    Co-Authors: Feng Wang, Michael A. Hickner, William Harrison, Jeffrey B Mecham, Thomas A Zawodzinski, James E Mcgrath
    Abstract:

    Novel biphenol-based wholly aromatic poly (arylene ether sulfones) containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of disodium 3,3'-disulfonate-4,4'-dichlorodiphenyl sulfone (SDCDPS), 4,4'-dichlorodiphenylsulfone (DCDPS) and biphenol. Copolymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at 190°C in the presence of anhydrous potassium carbonate. Tough membranes were successfully cast from the control and the copolymers, which had a SDCDPS/DCDPS mole ratio of either 40:60 or 60:40 using N,N-dimethylactamide; the 100% SDCDPS homopolymer was water soluble. Short-term aging (30 min) indicates that the desired acid form membranes are stable to 220°C in air and conductivity values at 25°C of 0.110 (40%) and 0.170 S/cm (60%) were measured, which are comparable to or higher than the state-of-the art fluorinated copolymer Nafion 1135 control. The new copolymers, which contain ion conductivity sites on deactivated rings, are candidates as new polymeric electrolyte materials for proton exchange membrane (PEM) fuel cells. Further research comparing their membrane behavior to post-sulfonated systems is in progress.

  • Phosphonyl/hydroxyl hydrogen bonding-induced miscibility of poly(arylene ether phosphine oxide/sulfone) statistical copolymers with poly(hydroxy ether) (phenoxy resin) : Synthesis and characterization
    Journal of Polymer Science Part B, 1999
    Co-Authors: Sheng Wang, Q. Ji, C. N. Tchatchoua, Allan R. Shultz, James E Mcgrath
    Abstract:

    High molecular weight bisphenol A or hydroquinone-based poly(arylene ether phosphine oxide/sulfone) homopolymer or statistical copolymers were synthesized and characterized by thermal analysis, gel permeation chromatography, and intrinsic viscosity. Miscibility studies of blends of these copolymers with a (bisphenol A)-epichlorohydrin based poly(hydroxy ether), termed phenoxy resin, were conducted by infrared spectroscopy, dynamic mechanical analysis, and differential scanning calorimetry. All of the data are consistent with strong hydrogen bonding between the phosphonyl groups of the copolymers and the pendent hydroxyl groups of the phenoxy resin as the miscibility-inducing mechanism. Complete miscibility at all blend compositions was achieved with as little as 20 mol % of phosphine oxide units in the bisphenol A poly(arylene ether phosphine oxide/sulfone) copolymer. Single glass transition temperatures (Tg) from about 100 to 200°C were achieved. Replacement of bisphenol A by hydroquinone in the copolymer synthesis did not significantly affect blend miscibilities. Examination of the data within the framework of four existing blend Tg composition equations revealed Tg elevation attributable to phosphonyl/hydroxyl hydrogen bonding interactions. Because of the structural similarities of phenoxy, epoxy, and vinylester resins, the new poly(arylene ether phosphine oxide/sulfone) copolymers should find many applications as impact-improving and interphase materials in thermoplastics and thermoset composite blend compositions. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1849–1862, 1999

Evan A Scott - One of the best experts on this subject based on the ideXlab platform.

  • homopolymer self assembly of poly propylene sulfone hydrogels via dynamic noncovalent sulfone sulfone bonding
    Nature Communications, 2020
    Co-Authors: Baofu Qiao, Trung Dac Nguyen, Michael Vincent, Sharan Bobbala, Chamille Lescott, Vinayak P Dravid, Monica Olvera De La Cruz, Evan A Scott
    Abstract:

    Natural biomolecules such as peptides and DNA can dynamically self-organize into diverse hierarchical structures. Mimicry of this homopolymer self-assembly using synthetic systems has remained limited but would be advantageous for the design of adaptive bio/nanomaterials. Here, we report both experiments and simulations on the dynamic network self-assembly and subsequent collapse of the synthetic homopolymer poly(propylene sulfone). The assembly is directed by dynamic noncovalent sulfone–sulfone bonds that are susceptible to solvent polarity. The hydration history, specified by the stepwise increase in water ratio within lower polarity water-miscible solvents like dimethylsulfoxide, controls the homopolymer assembly into crystalline frameworks or uniform nanostructured hydrogels of spherical, vesicular, or cylindrical morphologies. These electrostatic hydrogels have a high affinity for a wide range of organic solutes, achieving >95% encapsulation efficiency for hydrophilic small molecules and biologics. This system validates sulfone–sulfone bonding for dynamic self-assembly, presenting a robust platform for controllable gelation, nanofabrication, and molecular encapsulation. Natural biomolecules such as peptides and DNA can dynamically self-organize into diverse hierarchical structures. Here the authors report experiments and simulations on the dynamic network self-assembly and subsequent collapse of the synthetic homopolymer poly(propylene sulfone).

  • Homopolymer self-assembly of poly(propylene sulfone) hydrogels via dynamic noncovalent sulfone-sulfone bonding.
    Nature Communications, 2020
    Co-Authors: Baofu Qiao, Trung Dac Nguyen, Michael Vincent, Sharan Bobbala, Chamille Lescott, Vinayak P Dravid, Monica Olvera De La Cruz, Evan A Scott
    Abstract:

    Natural biomolecules such as peptides and DNA can dynamically self-organize into diverse hierarchical structures. Mimicry of this homopolymer self-assembly using synthetic systems has remained limited but would be advantageous for the design of adaptive bio/nanomaterials. Here, we report both experiments and simulations on the dynamic network self-assembly and subsequent collapse of the synthetic homopolymer poly(propylene sulfone). The assembly is directed by dynamic noncovalent sulfone-sulfone bonds that are susceptible to solvent polarity. The hydration history, specified by the stepwise increase in water ratio within lower polarity water-miscible solvents like dimethylsulfoxide, controls the homopolymer assembly into crystalline frameworks or uniform nanostructured hydrogels of spherical, vesicular, or cylindrical morphologies. These electrostatic hydrogels have a high affinity for a wide range of organic solutes, achieving >95% encapsulation efficiency for hydrophilic small molecules and biologics. This system validates sulfone-sulfone bonding for dynamic self-assembly, presenting a robust platform for controllable gelation, nanofabrication, and molecular encapsulation.

Mitsuru Ueda - One of the best experts on this subject based on the ideXlab platform.