Polymer supported gold nanoparticles: Synthesis and characterization of functionalized polystyrene-supported gold nanoparticles and their application in catalytic oxidation of alcohols in water

NASA Astrophysics Data System (ADS)

Kaboudin, Babak; Khanmohammadi, Hamid; Kazemi, Foad

2017-12-01

Sulfonated polystyrene microsphere were functionalized using ethylene diamine to introduce amine groups to the polymer chains. The amine functionalized polymers were used as a support for gold nanoparticles. A thorough structural characterization has been carried out by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) images, EDS, CHN and atomic absorption spectroscopy. The polymer supported gold nanoparticles was found to be an efficient catalyst for the oxidation of alcohols in water.

New cation-exchange material based on a sulfonated 3,4-ethylenedioxythiophene monomer

NASA Astrophysics Data System (ADS)

Stéphan, O.; Schottland, P.; Le Gall, P.-Y.; Chevrot, C.

1998-06-01

The electrochemical oxidation, in aqueous medium, of a 3,4-ethylenedioxythiophene monomer functionalized by a sulfonate group exhibiting cation-exchange properties, allows the synthesis of a new type of water-soluble material. In order to synthesize in water, by oxidative electropolymerization, polymer films of controlled thickness containing attached sulfonate groups, we have investigated the polymerization of the functionalized monomer in the presence of the unsubstituted one without supporting electrolyte. Using an equimolar mixture (0.01 mol/l) of both monomers, copolymers exhibiting cation exchange abilities have been synthesized. As an example, th easy incorporation of hexaamine-ruthenium(III) into one of these copolymers is briefly reported. L'oxydation électrochimique en milieu aqueux d'un monomère de type 3,4- éthylènedioxythiophène fonctionnalisé par un groupement sulfonate permet d'envisager la synthèse d'un nouveau type de polymère hydrosoluble. Afin d'obtenir électrochimiquement en milieu aqueux, un film de polymère d'épaisseur contrôlée contenant des groupements sulfonates, nous avons evisagé de polymériser ce monomère en présence de son homologue non substitué. En partant d'un mélange équimolaire (0.01 mol/l) des deux monomères et en l'absence d'électrolyte support, nous avons synthétisé un matériau possédant des propriétés d'échange de cations. A titre d'exemple, nous présentons brièvement l'incorporation d'un complexe hexaaminé du ruthénium(III) dans un de ces copolymères.

Processes for preparing carbon fibers using sulfur trioxide in a halogenated solvent

DOEpatents

Patton, Jasson T.; Barton, Bryan E.; Bernius, Mark T.; Chen, Xiaoyun; Hukkanen, Eric J.; Rhoton, Christina A.; Lysenko, Zenon

2015-12-29

Disclosed here are processes for preparing carbonized polymers (preferably carbon fibers), comprising sulfonating a polymer with a sulfonating agent that comprises SO.sub.3 dissolved in a solvent to form a sulfonated polymer; treating the sulfonated polymer with a heated solvent, wherein the temperature of the solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 500-3000.degree. C. Carbon fibers made according to these methods are also disclosed herein.

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor.

PubMed

Munirathinam, Rajesh; Ricciardi, Roberto; Egberink, Richard J M; Huskens, Jurriaan; Holtkamp, Michael; Wormeester, Herbert; Karst, Uwe; Verboom, Willem

2013-01-01

Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2-3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydration of oximes, using cinnamaldehyde oxime as a model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3.

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

DOEpatents

Fish, R.H.

1987-04-21

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

DOEpatents

Fish, Richard H.

1987-01-01

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

New Porous Crystals of Extended Metal-Catecholates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hmadeh, Mohamad; Lu, Zheng; Liu, Zheng

To date, the links of robust and highly porous metal organic frameworks (MOFs) have been largely limited to carboxylate,(1) imidazolate,(2) other azolates,(3) or sulfonate.(4) Although catecholate organic units are well-known and are employed heavily for metal chelation in biology,(5) only the simple 1,2,4,5-tetrahydroxybenzene (H6C6O4)(6) or 1,4-dihydroxy-benzoquinone and their homologues (H2C6X2O4, e.g., X = Cl, Br, NO2 and CH3) have been explored and incorporated into extended frameworks (Scheme S1 in the Supporting Information).(7) Herein, we describe linking the highly conjugated tricatecholate, 2,3,6,7,10,11-hexahydroxytriphenylene (H12C18O6, HHTP), with Co(II) and Ni(II) ions into two-dimensional porous extended frameworks. These new crystalline materials, termed metal-catecholates (M-CATs),more » were characterized by X-ray diffraction techniques (single crystal for Co-CAT-1, and powder for Ni-CAT-1) and high-resolution transmission electron microscopy (HR-TEM) studies (for Ni-CAT-1). We demonstrate their high chemical stability (in aqueous and non-aqueous media), thermal stability, and porosity. Cu-CAT-1 microcrystalline material showed high electrical conductivity and charge storage capacity.« less

Electrochemical sensor for catechol and dopamine based on a catalytic molecularly imprinted polymer-conducting polymer hybrid recognition element.

PubMed

Lakshmi, Dhana; Bossi, Alessandra; Whitcombe, Michael J; Chianella, Iva; Fowler, Steven A; Subrahmanyam, Sreenath; Piletska, Elena V; Piletsky, Sergey A

2009-05-01

One of the difficulties with using molecularly imprinted polymers (MIPs) and other electrically insulating materials as the recognition element in electrochemical sensors is the lack of a direct path for the conduction of electrons from the active sites to the electrode. We have sought to address this problem through the preparation and characterization of novel hybrid materials combining a catalytic MIP, capable of oxidizing the template, catechol, with an electrically conducting polymer. In this way a network of "molecular wires" assists in the conduction of electrons from the active sites within the MIP to the electrode surface. This was made possible by the design of a new monomer that combines orthogonal polymerizable functionality; comprising an aniline group and a methacrylamide. Conducting films were prepared on the surface of electrodes (Au on glass) by electropolymerization of the aniline moiety. A layer of MIP was photochemically grafted over the polyaniline, via N,N'-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Detection of catechol by the hybrid-MIP sensor was found to be specific, and catechol oxidation was detected by cyclic voltammetry at the optimized operating conditions: potential range -0.6 V to +0.8 V (vs Ag/AgCl), scan rate 50 mV/s, PBS pH 7.4. The calibration curve for catechol was found to be linear to 144 microM, with a limit of detection of 228 nM. Catechol and dopamine were detected by the sensor, whereas analogues and potentially interfering compounds, including phenol, resorcinol, hydroquinone, serotonin, and ascorbic acid, had minimal effect (< or = 3%) on the detection of either analyte. Non-imprinted hybrid electrodes and bare gold electrodes failed to give any response to catechol at concentrations below 0.5 mM. Finally, the catalytic properties of the sensor were characterized by chronoamperometry and were found to be consistent with Michaelis-Menten kinetics.

Two-step sulfonation process for the conversion of polymer fibers to carbon fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barton, Bryan E.; Patton, Jasson T.; Hukkanen, Eric J.

Disclosed herein are processes for preparing carbon fibers, comprising: sulfonating a polymer fiber with a sulfonating agent that is fuming sulfuric acid, sulfuric acid, chlorosulfonic acid, or a combination thereof; treating the sulfonated polymer with a heated solvent, wherein the temperature of the heated solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 501-3000.degree. C. Carbon fibers prepared according to these methods are also disclosed herein.

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

PubMed Central

Munirathinam, Rajesh; Ricciardi, Roberto; Egberink, Richard J M; Huskens, Jurriaan; Holtkamp, Michael; Wormeester, Herbert; Karst, Uwe

2013-01-01

Summary Polystyrene sulfonate polymer brushes, grown on the interior of the microchannels in a microreactor, have been used for the anchoring of gallium as a Lewis acid catalyst. Initially, gallium-containing polymer brushes were grown on a flat silicon oxide surface and were characterized by FTIR, ellipsometry, and X-ray photoelectron spectroscopy (XPS). XPS revealed the presence of one gallium per 2–3 styrene sulfonate groups of the polymer brushes. The catalytic activity of the Lewis acid-functionalized brushes in a microreactor was demonstrated for the dehydration of oximes, using cinnamaldehyde oxime as a model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3. PMID:24062830

Toxicity of pyrolysis gases from synthetic polymers

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Soriano, J. A.; Kosola, K. L.; Kourtides, D. A.; Parker, J. A.

1977-01-01

The screening test method was used to investigate toxicity in polyethylene, polystyrene, polymethyl methacrylate, polyaryl sulfone, polyether sulfone, polyphenyl sulfone, and polyphenylene sulfide. Changing from a rising temperature program to a fixed temperature program resulted on shorter times to animal responses. This effect was attributed in part to more rapid generation of toxicants. The toxicants from the sulfur containing polymers appeared to act more rapidly than the toxicants from the other polymers. It was not known whether this effect was due primarily to difference in concentration or in the nature of the toxicants. The carbon monoxide concentration found did not account for the results observed with the sulfur containing polymers. Polyphenyl sulfone appeared to exhibit the least toxicity among the sulfur containing polymers evaluated under these test conditions.

Bio-inspired Self-healing Composite Hydrogel with Iron Oxide Nanoparticle as Coordination Crosslinker

NASA Astrophysics Data System (ADS)

Li, Qiaochu; Barret, Devin G.; Messersmith, Phillip B.; Holten-Andersen, Niels

2014-03-01

Polymer-nanoparticle (NP) composites have attracted renewed attention due to enhanced mechanical strength combined with various functionalities, but controlling the interfacial chemistry between NPs and polymer matrix, which is crucial for the composite's mechanical behavior, remains a major challenge. Inspired by the adhesion chemistry of mussel fibers, we investigated a novel approach to incorporate Fe3O4 NPs into hydrogel matrix. A polyethylene glycol polymer is designed with both ends conjugated by catechol groups, which have strong coordination affinity to Fe. The polymer network is crosslinked via coordination bonding at the surface of Fe3O4 NPs, yielding a stiff nanocomposite hydrogel. Due to the reversible nature of coordination bonding, the hydrogel presents self-healing behavior. Oscillatory rheology allows comparative kinetic studies of self-healing driven by catechol bonding at Fe3O4 NP interfaces and by catechol-Fe3+ coordination complexes. Furthermore, the superparamagnetic property of Fe3O4 NP is preserved after gelation, allowing for response to external stimuli. This gelation motif can serve as a versatile platform for tuning functional and mechanical properties for future polymer nanocomposite materials.

Impact of Polymer Electrolyte Membrane Degradation Products on Oxygen Reduction Reaction Activity for Platinum Electrocatalysts

DOE PAGES

Christ, J. M.; Neyerlin, K. C.; Wang, H.; ...

2014-10-30

The impact of model membrane degradation compounds on the relevant electrochemical parameters for the oxygen reduction reaction (i.e. electrochemical surface area and catalytic activity), was studied for both polycrystalline Pt and carbon supported Pt electrocatalysts. Model compounds, representing previously published, experimentally determined polymer electrolyte membrane degradation products, were in the form of perfluorinated organic acids that contained combinations of carboxylic and/or sulfonic acid functionality. Perfluorinated carboxylic acids of carbon chain length C1 – C6 were found to have an impact on electrochemical surface area (ECA). The longest chain length acid also hindered the observed oxygen reduction reaction (ORR) performance, resultingmore » in a 17% loss in kinetic current (determined at 0.9 V). Model compounds containing sulfonic acid functional groups alone did not show an effect on Pt ECA or ORR activity. Lastly, greater than a 44% loss in ORR activity at 0.9V was observed for diacid model compounds DA-Naf (perfluoro(2-methyl-3-oxa-5-sulfonic pentanoic) acid) and DA-3M (perfluoro(4-sulfonic butanoic) acid), which contained both sulfonic and carboxylic acid functionalities.« less

Controlling Hydrogel Mechanics via Bio-Inspired Polymer-Nanoparticle Bond Dynamics.

PubMed

Li, Qiaochu; Barrett, Devin G; Messersmith, Phillip B; Holten-Andersen, Niels

2016-01-26

Interactions between polymer molecules and inorganic nanoparticles can play a dominant role in nanocomposite material mechanics, yet control of such interfacial interaction dynamics remains a significant challenge particularly in water. This study presents insights on how to engineer hydrogel material mechanics via nanoparticle interface-controlled cross-link dynamics. Inspired by the adhesive chemistry in mussel threads, we have incorporated iron oxide nanoparticles (Fe3O4 NPs) into a catechol-modified polymer network to obtain hydrogels cross-linked via reversible metal-coordination bonds at Fe3O4 NP surfaces. Unique material mechanics result from the supra-molecular cross-link structure dynamics in the gels; in contrast to the previously reported fluid-like dynamics of transient catechol-Fe(3+) cross-links, the catechol-Fe3O4 NP structures provide solid-like yet reversible hydrogel mechanics. The structurally controlled hierarchical mechanics presented here suggest how to develop hydrogels with remote-controlled self-healing dynamics.

Sulfonated Copper Phthalocyanine/Sulfonated Polysulfone Composite Membrane for Ionic Polymer Actuators with High Power Density and Fast Response Time.

PubMed

Kwon, Taehoon; Cho, Hyeongrae; Lee, Jang-Woo; Henkensmeier, Dirk; Kang, Youngjong; Koo, Chong Min

2017-08-30

Ionic polymer composite membranes based on sulfonated poly(arylene ether sulfone) (SPAES) and copper(II) phthalocyanine tetrasulfonic acid (CuPCSA) are assembled into bending ionic polymer actuators. CuPCSA is an organic filler with very high sulfonation degree (IEC = 4.5 mmol H + /g) that can be homogeneously dispersed on the molecular scale into the SPAES membrane, probably due to its good dispersibility in SPAES-containing solutions. SPAES/CuPCSA actuators exhibit larger ion conductivity (102 mS cm -1 ), tensile modulus (208 MPa), strength (101 MPa), and strain (1.21%), exceptionally faster response to electrical stimuli, and larger mechanical power density (3028 W m -3 ) than ever reported for ion-conducting polymer actuators. This outstanding actuation performance of SPAES/CuPCSA composite membrane actuators makes them attractive for next-generation transducers with high power density, which are currently developed, e.g., for underwater propulsion and endoscopic surgery.

Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.

PubMed

Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok

2014-10-01

Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211.

Sulfonated polystyrene and its characterization as a material of electrolyte polymer

NASA Astrophysics Data System (ADS)

Ngadiwiyana; Ismiyarto; Gunawan; Purbowatiningrum, RS; Prasetya, N. B. A.; Kusworo, T. D.; Susanto, H.

2018-05-01

The research of polystyrene modification from Styrofoam waste and its application as a main material of electrolyte polymer had been done. The sulfonation reaction of polystyrene was conducted using sulfuric acid as sufonation agent and the reactions were done with variation times of 1, 2, 3, 4 and 5 h. The characterization of the sulfonated products covered analysis of functional groups using FT-IR spectrophotometer, sulfonation degree, measurements of ion exchange capacity, conductivity and swelling degree. The sulfonated polystyrene product was white solid as confirmed by the spectra of FT-IR with the presence of wide band absorption of O=S=O at the wavenumber of 1080-1411 cm-1 as indication. The research showed the best sulfonated polystyrene prepared in 4 h as a material of electrolyte polymer, since it had the highest degree of sulfonation, ion exchange capacity, conductivity and swelling degree with the values were 28.52 %, 1.550 meg/g, 15,924.10-6 Ω-1cm-1 and 332.4 %, respectively.

Anhydrous state proton and lithium ion conducting solid polymer electrolytes based on sulfonated bisphenol-A-poly(arylene ethers)

NASA Astrophysics Data System (ADS)

Guha Thakurta, Soma

Sulfonated polymer based solid polymer electrolytes (SPEs) have received considerable interest in recent years because of their wide variety of applications particularly in fuel cells, batteries, supercapacitors, and electrochromic devices. The present research was focused on three interrelated subtopics. First, two different bisphenol-A-poly(arylene ethers), polyetherimide (PEI) and polysulfone (PSU) were sulfonated by a post sulfonation method to various degrees of sulfonation, and their thermal and mechanical properties were examined. The effects of poly(arylene ether) chemical structure, reaction time, concentration, and types of sulfonating agents on sulfonation reaction were investigated. It was found that deactivation of bisphenol A unit caused by the electron withdrawing imide, retarded the sulfonation of PEI compared to PSU. Sulfonation conducted with a high concentration of sulfonating agent and/or prolonged reaction time exhibited evidence of degradation at the isopropylidene unit. The degradation occurred through the same mechanistic pathway with the two different sulfonating agents, chlorosulfonic acid (CSA) and trimethylsilyl chlorosulfonate (TMSCS). The degradation was faster with CSA than its silyl ester, TMSCS, and was evident even at low acid concentration. Second, novel anhydrous proton conducting solid polymer electrolytes (SPEs) were prepared by the incorporation of 1H-1,2,4-triazole (Taz) as a proton solvent in sulfonated polyetherimide (SPEI) matrix. The size, shape, and state of dispersion (crystal morphology) of triazole crystals in SPEI were examined as a function of degree of sulfonation and triazole concentration. Increasing sulfonic acid content caused reduction of triazole crystallite size, hence the depression of melting temperature and their uniform distribution throughout the sulfonated polymer matrix. The increased rate of structure diffusion within the smaller size crystals due to the improved molecular mobility contributed significantly to the anhydrous state proton conductivity. Third, a new category of single lithium ion conducting SPEs was developed by crosslinking a polyether epoxy, poly(ethylene glycol)diglicidyl ether (PEGDGE) (lithium ion solvent), in sulfonated polysulfone (SPSU) matrix. The effects of degree of sulfonation and electrolyte composition on ionic conductivity, thermal, and tensile properties of SPEs were investigated. It was found that ion-dipole interactions between lithium sulfonate (SO3Li) and PEGDGE were responsible for the reduction in size of the dispersed epoxy phase and increased thermal stability. Lithium sulfonate promoted compatibilization and also caused improvement in elongation at break. A low molecular weight electrolyte salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was further dissolved in PEGDGE phase prior to its crosslinking in SPSU matrix, and the ionic conductivity and thermal properties were evaluated as a function of doping level. The ionic conductivity showed remarkable improvement compared to the undoped system.

Sulfonated polyphenylene polymers

DOEpatents

Cornelius, Christopher J.; Fujimoto, Cy H.; Hickner, Michael A.

2007-11-27

Improved sulfonated polyphenylene compositions, improved polymer electrolyte membranes and nanocomposites formed there from for use in fuel cells are described herein. The improved compositions, membranes and nanocomposites formed there from overcome limitations of Nafion.RTM. membranes.

Chitosan-catechol: a writable bioink under serum culture media.

PubMed

Lee, Daiheon; Park, Joseph P; Koh, Mi-Young; Kim, Pureum; Lee, Junhee; Shin, Mikyung; Lee, Haeshin

2018-05-01

Mussel-inspired adhesive coatings on biomedical devices have attracted significant interest due to their unique properties such as substrate independency and high efficiency. The key molecules for mussel-inspired adhesive coatings are catechol and amine groups. Along with the understanding of catechol chemistry, chitosan-catechol has also been developed as a representative mussel-inpired adhesive polymer that contains catechol and amine groups for adhesiveness. Herein, we demonstrated the direct writability of chitosan-catechol as a bioink for 3D printing, one of the additive techniques. The use of chitosan-catechol bioink results in the formation of 3D constructs in normal culture media via rapid complexation of this bioink with serum proteins; in addition, the metal/catechol combination containing tiny amounts of vanadyl ions, in which the ratio of metal to catechol is 0.0005, dramatically enhances the mechanical strength and printability of the cell-encapsulated inks, showing a cell viability of approximately 90%. These findings for mussel-inspired bioinks will be a promising way to design a biocompatible 3D bioink cross-linked without any external stimuli.

A new composite consisting of electrosynthesized conducting polymers, graphene sheets and biosynthesized gold nanoparticles for biosensing acute lymphoblastic leukemia.

PubMed

Mazloum-Ardakani, Mohammad; Barazesh, Behnaz; Khoshroo, Alireza; Moshtaghiun, Mohammad; Sheikhha, Mohammad Hasan

2018-06-01

In this work we report the synthesis of a stable composite with excellent electrical properties, on the surface of a biosensor. Conductive polymers offer both high electrical conductivity and mechanical strength. Many reports have focused on synthesizing conductive polymers with the aid of high-cost enzymes. In the current work we introduce a novel electrochemical, one-step, facile and cost effective procedure for synthesizing poly (catechol), without using expensive enzymes. The poly (catechol) conductivity was enhanced by modification with graphene sheets and biosynthesized gold nanoparticles. Four different robust methods, DPV, EIS, CV and chronoamperometry, were used to monitor the biosensor modifications. The peak currents of the catechol (an electroactive probe) were linearly related to the logarithm of the concentrations of target DNA in the range 100.0 μM to 10.0 pM, with a detection limit of 1.0 pM for the DNA strand. The current work investigates a new, stable composite consisting of conductive polymers and nanoparticles, which was applied to the detection of acute lymphoblastic leukemia. Copyright © 2018 Elsevier B.V. All rights reserved.

B, N co-doped carbon from cross-linking induced self-organization of boronate polymer for supercapacitor and oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Chang, Ying; Yuan, Conghui; Liu, Cheng; Mao, Jie; Li, Yuntong; Wu, Haiyang; Wu, Yuzhe; Xu, Yiting; Zeng, Birong; Dai, Lizong

2017-10-01

A novel strategy has been developed to generate B, N co-doped carbon materials (CNBs) through the pyrolysis of boronate polymer nanoparticles (BPNs) derived from the condensation reaction between catechol and boronic monomers. The morphology, surface area and heteroatom (viz. B and N) content of the CNBs can be easily adjusted by altering the molar ratio between catechol and boronic monomers. The supercapacitor and oxygen reduction reaction (ORR) performance of the CNBs are optimized. CNBs derived from equal molar ratio of catechol and boronic monomers exhibit favorable performance for supercapacitor, featuring a specific capacitance of up to 299.4 F/g at 0.2 A/g, an improved rate capability and excellent cycle stability. Notably, CNBs prepared using 1/2 molar ratio of catechol to boronic monomers show excellent ORR performance, as they demonstrate good electrocatalytic activity, high tolerance for methanol and long durability. Our findings may be of interest in the design of carbon materials with optimized electrochemical properties through the control over surface area and the content of heteroatom.

Relative toxicity of pyrolysis products of some synthetic polymers

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Slattengren, C. L.; Furst, A.; Kourtides, D. A.; Parker, J. A.

1976-01-01

Nineteen samples of synthetic polymers were evaluated for relative toxicity in the course of characterizing materials intended for aircraft interior applications. The generic polymers included ABS, chlorinated PVC, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryl sulfone, polyether sulfone, polybismaleimide, and polyvinyl fluoride. Test results are presented, and compared in relative rankings with similar results on cellulosic materials and other synthetic polymers. Under these test conditions, the samples of synthetic polymers were either comparable to or significantly less toxic than the samples of commercial cellulosic materials.

Sulfonimide-containing poly(arylene ether)s and poly(arylene ether sulfone)s, methods for producing the same, and uses thereof

DOEpatents

Hofmann, Michael A.

2006-11-14

The present invention is directed to sulfonimide-containing polymers, specifically sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, and processes for making the sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, for use conductive membranes and fuel cells.

Colorful Polyelectrolytes: An Atom Transfer Radical Polymerization Route to Fluorescent Polystyrene Sulfonate.

PubMed

Huberty, Wayne; Tong, Xiaowei; Balamurugan, Sreelatha; Deville, Kyle; Russo, Paul S; Zhang, Donghui

2016-03-01

A labeled green fluorescent polystyrene sulfonate (LNaPSS) has been synthesized using atom transfer radical polymerization of a styrene sulfonate monomer with a fluorescent co-monomer, fluorescein thiocyanate-vinyl aniline. As a result this 100 % sulfonated polymer contains no hydrophobic patches along the chain backbone besides the fluorescent marker itself. The concentration of the fluorescent monomer was kept low to maintain the characteristic properties of the anionic polyelectrolyte, LNaPSS. ATRP conditions facilitated the production of polymers spanning a range of molecular weights from 35,000 to 175,000 in gram-scale batches with polydispersity indices of 1.01-1.24. Molecular weight increased with the monomer to initiator ratio. Gel permeation chromatography results show a unimodal distribution, and the polymer structure was also confirmed by (1)H NMR and FT-IR spectroscopy. Fluorescence spectroscopy confirmed covalent bonding of fluorescein isothiocyanate to the polymer, indicating that the polymer is suitable as a probe in fluorescence microscopy. To demonstrate this ability, the polymer was used to locate structural features in salt crystals formed during drying, as in the evaporation of sea mist. A second application to probe diffusion studies is also demonstrated.

Investigation of the adsorption of polymer chains on amine-functionalized double-walled carbon nanotubes.

PubMed

Ansari, R; Ajori, S; Rouhi, S

2015-12-01

Molecular dynamics (MD) simulations were used to study the adsorption of different polymer chains on functionalized double-walled carbon nanotubes (DWCNTs). The nanotubes were functionalized with two different amines: NH2 (a small amine) and CH2-NH2 (a large amine). Considering three different polymer chains, all with the same number of atoms, the effect of polymer type on the polymer-nanotube interaction was studied. In general, it was found that covalent functionalization considerably improved the polymer-DWCNT interaction. By comparing the results obtained with different polymer chains, it was observed that, unlike polyethylene and polyketone, poly(styrene sulfonate) only weakly interacts with the functionalized DWCNTs. Accordingly, the smallest radius of gyration was obtained with adsorbed poly(styrene sulfonate). It was also observed that the DWCNTs functionalized with the large amine presented more stable interactions with polyketone and poly(styrene sulfonate) than with polyethylene, whereas the DWCNTs functionalized with the small amine showed better interfacial noncovalent bonding with polyethylene.

High-performance mussel-inspired adhesives of reduced complexity.

PubMed

Ahn, B Kollbe; Das, Saurabh; Linstadt, Roscoe; Kaufman, Yair; Martinez-Rodriguez, Nadine R; Mirshafian, Razieh; Kesselman, Ellina; Talmon, Yeshayahu; Lipshutz, Bruce H; Israelachvili, Jacob N; Waite, J Herbert

2015-10-19

Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m(-2)) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule.

Bioinspired Catecholic Primers for Rigid and Ductile Dental Resin Composites.

PubMed

Shin, Eeseul; Ju, Sung Won; An, Larry; Ahn, Eungjin; Ahn, Jin-Soo; Kim, Byeong-Su; Ahn, B Kollbe

2018-01-17

In the construction of dental restorative polymer composite materials, surface priming on mineral fillers is essential to improve the mechanical performance of the composites. Here we present bioinspired catechol-functionalized primers for a tougher dental resin composite containing glass fillers. The catecholic primers with different polymerizable end groups were designed and then coated on glass surfaces using a simple drop-casting or dip-coating process. The surface binding ability and possible cross-linking (coupling or chemical bridging between the glass substrate and the dental resin) of the catecholic bifunctional primers were evaluated using atomic force microscopy, contact angle measurements, and the knife shear bonding test and compared to a state-of-the-art silane-based coupling agent. Various mechanical tests including shrinkage and compression tests of the dental resin composites were also conducted. Compression tests of the composites containing the catecholic primed fillers exhibited enhanced mechanical properties, owing to the bidentate hydrogen bonding of catechol moieties to the oxide mineral surface. Furthermore, the superior biocompatibility of the primed surface was confirmed via cell attachment assay, thus providing applicability of catecholic primers for practical dental and biomedical applications.

Rapid Self-healing Nanocomposite Hydrogel with Tunable Dynamic Mechanics

NASA Astrophysics Data System (ADS)

Li, Qiaochu; Mishra, Sumeet; Chapman, Brian; Chen, Pangkuan; Tracy, Joseph; Holten-Andersen, Niels

The macroscopic healing rate and efficiency in self-repairing hydrogel materials are largely determined by the dissociation dynamics of their polymer network, which is hardly achieved in a controllable manner. Inspired by mussel's adhesion chemistry, we developed a novel approach to assemble inorganic nanoparticles and catechol-decorated PEG polymer into a hydrogel network. When utilized as reversible polymer-particle crosslinks, catechol-metal coordination bonds yield a unique gel network with dynamic mechanics controlled directly by interfacial crosslink structure. Taking advantage of this structure-property relationship at polymer-particle interfaces, we designed a hierarchically structured hybrid gel with two distinct relaxation timescales. By tuning the relative contribution of the two relaxation modes, we are able to finely control the gel's dynamic mechanical behavior from a viscoelastic fluid to a stiff solid, yet preserving its rapid self-healing property without the need for external stimuli.

Polymer electrolytes based on sulfonated polysulfone for direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Lufrano, F.; Baglio, V.; Staiti, P.; Arico', A. S.; Antonucci, V.

This paper reports the development and characterization of sulfonated polysulfone (SPSf) polymer electrolytes for direct methanol fuel cells. The synthesis of sulfonated polysulfone was performed by a post sulfonation method using trimethyl silyl chlorosulfonate as a mild sulfonating agent. Bare polysulfone membranes were prepared with two different sulfonation levels (60%, SPSf-60 and 70%, SPSf-70), whereas, a composite membrane of SPSf-60 was prepared with 5 wt% silica filler. These membranes were investigated in direct methanol fuel cells (DMFCs) operating at low (30-40 °C) and high temperatures (100-120 °C). DMFC power densities were about 140 mW cm -2 at 100 °C with the bare SPSf-60 membrane and 180 mW cm -2 at 120 °C with the SPSf-60-SiO2 composite membrane. The best performance achieved at ambient temperature using a membrane with high degree of sulfonation (70%, SPSf-70) was 20 mW cm -2 at atmospheric pressure. This makes the polysulfone-based DMFC suitable for application in portable devices.

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, Richard H.

1986-01-01

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

High-performance mussel-inspired adhesives of reduced complexity

PubMed Central

Ahn, B. Kollbe; Das, Saurabh; Linstadt, Roscoe; Kaufman, Yair; Martinez-Rodriguez, Nadine R.; Mirshafian, Razieh; Kesselman, Ellina; Talmon, Yeshayahu; Lipshutz, Bruce H.; Israelachvili, Jacob N.; Waite, J. Herbert

2015-01-01

Despite the recent progress in and demand for wet adhesives, practical underwater adhesion remains limited or non-existent for diverse applications. Translation of mussel-inspired wet adhesion typically entails catechol functionalization of polymers and/or polyelectrolytes, and solution processing of many complex components and steps that require optimization and stabilization. Here we reduced the complexity of a wet adhesive primer to synthetic low-molecular-weight catecholic zwitterionic surfactants that show very strong adhesion (∼50 mJ m−2) and retain the ability to coacervate. This catecholic zwitterion adheres to diverse surfaces and self-assembles into a molecularly smooth, thin (<4 nm) and strong glue layer. The catecholic zwitterion holds particular promise as an adhesive for nanofabrication. This study significantly simplifies bio-inspired themes for wet adhesion by combining catechol with hydrophobic and electrostatic functional groups in a small molecule. PMID:26478273

In situ S-K XANES study of polymer electrolyte fuel cells: changes in the chemical states of sulfonic groups depending on humidity.

PubMed

Isegawa, Kazuhisa; Nagami, Tetsuo; Jomori, Shinji; Yoshida, Masaaki; Kondoh, Hiroshi

2016-09-14

Changes in the chemical states of sulfonic groups of Nafion in polymer electrolyte fuel cells (PEFCs) under gas-flowing conditions were studied using in situ S-K XANES spectroscopy. The applied potential to the electrodes and the humidity of the cell were changed under flowing H 2 gas in the anode and He gas in the cathode. While the potential shows no significant effect on the S-K XANES spectra, the humidity is found to induce reversible changes in the spectra. Comparison of the spectral changes with simulations based on the density functional theory calculations indicates that the humidity influences the chemical state of the sulfonic group; under wet conditions the sulfonic group is in the form of a sulfonate ion. By drying treatment the sulfonate ion binds to hydrogen and becomes sulfonic acid. Furthermore, a small fraction of the sulfonic acid irreversibly decomposes to atomic sulfur. The peak energy of the atomic sulfur suggests that the generated atomic sulfur is adsorbed on the Pt catalyst surfaces.

Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Soriano, J. A.; Kosola, K. L.

1977-01-01

The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.

An Extraordinary Sulfonated-Graphenal-Polymer-Based Electrolyte Separator for All-Solid-State Supercapacitors.

PubMed

Liu, Xubo; Men, Chuanling; Zhang, Xiaohua; Li, Qingwen

2016-09-01

Sulfonated graphenal polymers can be assembled up by poly(vinyl alcohol) adhesion. The porous assembly structure results in a remarkably improved ionic conductivity and thus enhances electrochemical performances such as specific capacitance, capacitance retention, and cycling stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of arsenic compounds from petroliferous liquids

DOEpatents

Fish, R.H.

1984-04-06

The present invention in one aspect comprises a process for removing arsenic from petroliferous-derived liquids by contacting said liquid with a divinylbenzene-crosslinked polystyrene polymer (i.e. PS-DVB) having catechol ligands anchored to said polymer, said contacting being at an elevated temperature. In another aspect, the invention is a process for regenerating spent catecholated polystyrene polymer by removal of the arsenic bound to it from contacting petroliferous liquid in accordance with the aspect described above which regenerating process comprises: (a) treating said spent catecholated polystyrene polymer with an aqueous solution of at least one member selected from the group consisting of carbonates and bicarbonates of ammonium, alkali metals, and alkaline earth metals, said solution having a pH between about 8 and 10, and said treating being at a temperature in the range of about 20/sup 0/ to 100/sup 0/C; (b) separating the solids and liquids from each other. In a preferred embodiment the regeneration treatment is in two steps wherein step: (a) is carried out with an aqueous alcoholic carbonate solution which includes at least one lower alkyl alcohol, and, steps (c) and (d) are added. Steps (c) and (d) comprise: (c) treating the solids with an aqueous alcoholic solution of at least one ammonium, alkali or alkaline earth metal bicarbonate at a temperature in the range of about 20 to 100/sup 0/C; and (d) separating the solids from the liquids.

Polymer electrolyte membrane assembly for fuel cells

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S. (Inventor); Kindler, Andrew (Inventor); Yavrouian, Andre (Inventor); Halpert, Gerald (Inventor)

2002-01-01

An electrolyte membrane for use in a fuel cell can contain sulfonated polyphenylether sulfones. The membrane can contain a first sulfonated polyphenylether sulfone and a second sulfonated polyphenylether sulfone, wherein the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone have equivalent weights greater than about 560, and the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone also have different equivalent weights. Also, a membrane for use in a fuel cell can contain a sulfonated polyphenylether sulfone and an unsulfonated polyphenylether sulfone. Methods for manufacturing a membrane electrode assemblies for use in fuel cells can include roughening a membrane surface. Electrodes and methods for fabricating such electrodes for use in a chemical fuel cell can include sintering an electrode. Such membranes and electrodes can be assembled into chemical fuel cells.

Polymer electrolyte membrane assembly for fuel cells

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S. (Inventor); Kindler, Andrew (Inventor); Yavrouian, Andre (Inventor); Halpert, Gerald (Inventor)

2000-01-01

An electrolyte membrane for use in a fuel cell can contain sulfonated polyphenylether sulfones. The membrane can contain a first sulfonated polyphenylether sulfone and a second sulfonated polyphenylether sulfone, wherein the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone have equivalent weights greater than about 560, and the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone also have different equivalent weights. Also, a membrane for use in a fuel cell can contain a sulfonated polyphenylether sulfone and an unsulfonated polyphenylether sulfone. Methods for manufacturing a membrane electrode assemblies for use in fuel cells can include roughening a membrane surface. Electrodes and methods for fabricating such electrodes for use in a chemical fuel cell can include sintering an electrode. Such membranes and electrodes can be assembled into chemical fuel cells.

PEM Anchorage on Titanium Using Catechol Grafting

PubMed Central

Marie, Hélène; Barrere, Amélie; Schoentstein, Frédérique; Chavanne, Marie-Hélène; Grosgogeat, Brigitte; Mora, Laurence

2012-01-01

Background This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications. Methodology The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO2 substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium. Principal Findings Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed. Conclusions This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications. PMID:23226262

Poly(ester urea)-Based Adhesives: Improved Deployment and Adhesion by Incorporation of Poly(propylene glycol) Segments.

PubMed

Zhou, Jinjun; Bhagat, Vrushali; Becker, Matthew L

2016-12-14

The adhesive nature of mussels arises from the catechol moiety in the 3,4-dihydroxyphenylalanine (DOPA) amino acid, one of the many proteins that contribute to the unique adhesion properties of mussels. Inspired by these properties, many biomimetic adhesives have been developed over the past few years in an attempt to replace adhesives such as fibrin, cyanoacrylate, and epoxy glues. In the present work, we synthesized ethanol soluble but water insoluble catechol functionalized poly(ester urea) random copolymers that help facilitate delivery and adhesion in wet environments. Poly(propylene glycol) units incorporated into the polymer backbone impart ethanol solubility to these polymers, making them clinically relevant. A catechol to cross-linker ratio of 10:1 with a curing time of 4 h exceeded the performance of commercial fibrin glue (4.8 ± 1.4 kPa) with adhesion strength of 10.6 ± 2.1 kPa. These adhesion strengths are significant with the consideration that the adhesion studies were performed under wet conditions.

High performance anode based on a partially fluorinated sulfonated polyether for direct methanol fuel cells operating at 130 °C

NASA Astrophysics Data System (ADS)

Mack, Florian; Gogel, Viktor; Jörissen, Ludwig; Kerres, Jochen

2014-06-01

Due to the disadvantages of the Nafion polymer for the application in the direct methanol fuel cell (DMFC) especial at temperatures above 100 °C several polymers of the hydrocarbon type have already been investigated as membranes and ionomers in the DMFC. Among them were nonfluorinated and partially fluorinated arylene main-chain hydrocarbon polymers. In previous work, sulfonated polysulfone (sPSU) has been applied as the proton-conductive binder in the anode of a DMFC, ending up in good and stable performance. In continuation of this work, in the study presented here a polymer was prepared by polycondensation of decafluorobiphenyl and bisphenol AF. The formed polymer was sulfonated after polycondensation by oleum and the obtained partially fluorinated sulfonated polyether (SFS) was used as the binder and proton conductor in a DMFC anode operating at a temperature of 130 °C. The SFS based anode with 5% as ionomer showed comparable performance for the methanol oxidation to Nafion based anodes and significant reduced performance degradation versus Nafion and sPSU based anodes on the Nafion 115 membrane. Membrane electrode assemblies (MEAs) with the SFS based anode showed drastically improved performance compared to MEAs with Nafion based anodes during operation with lower air pressure at the cathode.

Structure and Dynamics Ionic Block co-Polymer Melts: Computational Study

NASA Astrophysics Data System (ADS)

Aryal, Dipak; Perahia, Dvora; Grest, Gary S.

Tethering ionomer blocks into co-polymers enables engineering of polymeric systems designed to encompass transport while controlling structure. Here the structure and dynamics of symmetric pentablock copolymers melts are probed by fully atomistic molecular dynamics simulations. The center block consists of randomly sulfonated polystyrene with sulfonation fractions f = 0 to 0.55 tethered to a hydrogenated polyisoprene (PI), end caped with poly(t-butyl styrene). We find that melts with f = 0.15 and 0.30 consist of isolated ionic clusters whereas melts with f = 0.55 exhibit a long-range percolating ionic network. Similar to polystyrene sulfonate, a small number of ionic clusters slow the mobility of the center of mass of the co-polymer, however, formation of the ionic clusters is slower and they are often intertwined with PI segments. Surprisingly, the segmental dynamics of the other blocks are also affected. NSF DMR-1611136; NERSC; Palmetto Cluster Clemson University; Kraton Polymers US, LLC.

Dynamics of water in sulfonated poly(phenylene) membranes

NASA Astrophysics Data System (ADS)

Osti, Naresh; Etampawala, Thusitha; Shrestha, Umesh; Perahia, Dvora; Cornelius, Christopher

2011-03-01

The dynamics of water in networks formed by highly rigid ionic polymers, sulfonated poly(phenylene) as observed by quasi elastic neutron scattering (QENS) is presented. These rigid ionic polymers have potential as effective ion exchange membranes with impact on a large number of applications from water purification to clean energy, where its rigidity distinguishes it from other ionic polymers. Its transport characteristics are affected by its rigidness as well as by direct interactions with the solvent. Our QENS studies as a function of sulfonation levels, temperature and solvent content have shown that on the time scale of the measurement, the polymers are rigid. While macroscopically all samples swell, and transport water, the water molecules appear locally rather confined. Water however remind non-frozen to subzero temperatures. The results will be discussed in view of theoretical models including continues diffusion and hopping of solvent molecules.

Controlling toughness and dynamics of polymer networks via mussel-inspired dynamical bonds

NASA Astrophysics Data System (ADS)

Filippidi, Emmanouela

For dry, thermoset, polymer systems increasing the degree of cross-linking increases the elastic modulus. However, it simultaneously compromises the elongation under tension, usually reducing the overall total energy dissipated before fracture (toughness). Dynamic reformable bonds and complex network topologies have been used to circumnavigate this issue with moderate success, mainly in hydrated network systems. Hydration, however, which swells these networks limits how far one could increase the modulus, while their chemistry prevents improvement of the mechanics upon drying. Employing the mussel byssus-inspired strategy of iron-catechol coordination bonds, we have synthesized and studied epoxy networks comprising covalently attached catechol moieties capable of forming additional iron-catechol complex cross-links that still function in dry conditions. In such a fashion, we create a high modulus, high elongation, high toughness material. The iron-catechol coordination bonds play multiple roles that enhance the mechanical performance of the system: at low strain and fast strain rates, they act like permanent cross-links with bonding strength similar to covalent bonds, but start disassociating at high elongation. They are also reformable, enabling material self-healing in a matter of minutes in the absence of load. Finally, the dissociative crosslink cleavage alters the local chain topology, creating length scales that unfold upon elongation. The elegance of this system lies on its general versatility. Both the polymer and metal ion can be used as control parameters to study the interplay of covalent and dynamical bonds as well as explore the limits of the design of elastomers with enhanced toughness. MRSEC of NSF Award No. DMR-1121053.

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, R.H.

1985-05-17

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids (shale oil, SRC, etc.) by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20/sup 0/ to 100/sup 0/C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

A Highly Aromatic and Sulfonated Ionomer for High Elastic Modulus Ionic Polymer Membrane Micro-Actuators

DTIC Science & Technology

2012-05-01

fluorophenyl)sulfone (DPA-PS:BP) is investigated for ionic polymer actuators. The uniqueness of DPA-PS:BP is that it can have a high ionic liquid (IL... ionic liquid Q M Zhang, Gokhan Hatipoglu, Yang Liu, Ran Zhao, Mitra Yoonessi, Dean M Tigelaar, Srinivas Tadigadapa Virginia Polytechnic Institute...DPA-PS:BP) is investigated for ionic polymer actuators. The uniqueness of DPA-PS:BP is that it can have a high ionic liquid (IL) uptake and

Graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated poly(arylene ether sulfone) for PEMFC applications.

PubMed

Zhang, Xuan; Hu, Zhaoxia; Luo, Linqiang; Chen, Shanshan; Liu, Jianmei; Chen, Shouwen; Wang, Lianjun

2011-07-15

Novel poly(arylene ether ketone) polymers with fluorophenyl pendants and phenoxide-terminated wholly sulfonated poly(arylene ether sulfone) oligomers are prepared via Ni(0)-catalyzed and nucleophilic polymerization, respectively, and subsequently used as starting materials to obtain graft-crosslinked membranes as polymer electrolyte membranes. The phenoxide-terminated sulfonated moieties are introduced as hydrophilic parts as well as crosslinking units. The chemical structure and morphology of the obtained membranes are confirmed by (1) H NMR and tapping-mode AFM. The properties required for fuel cell applications, including water uptake and dimensional change, as well as proton conductivity, are investigated. AFM results show a clear nanoscale phase-separation microstructure of the obtained membranes. The membranes show good dimensional stability and reasonably high proton conductivities under 30-90% relative humidity. The anisotropic proton conductivity ratios (σ(formula see text) ) of the membranes in water are in the range 0.65-0.92, and increase with an increase in hydrophilic block length. The results indicate that the graft-crosslinked membranes are promising candidates for applications as polymer electrolyte membranes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Healing Nanocomposite Hydrogel with Well-Controlled Dynamic Mechanics

NASA Astrophysics Data System (ADS)

Li, Qiaochu; Mishra, Sumeet; Chen, Pangkuan; Tracy, Joseph; Holten-Andersen, Niels

Network dynamics is a crucial factor that determines the macroscopic self-healing rate and efficiency in polymeric hydrogel materials, yet its controllability is seldom studied in most reported self-healing hydrogel systems. Inspired by mussel's adhesion chemistry, we developed a novel approach to assemble inorganic nanoparticles and catechol-decorated PEG polymer into a hydrogel network. When utilized as reversible polymer-particle crosslinks, catechol-metal coordination bonds yield a unique gel network with dynamic mechanics controlled directly by interfacial crosslink structure. Taking advantage of this structure-property relationship at polymer-particle interfaces, we next designed a hierarchically structured hybrid gel with two distinct relaxation timescales. By tuning the relative contribution of the two hierarchical relaxation modes, we are able to finely control the gel's dynamic mechanical behavior from a viscoelastic fluid to a stiff solid, yet preserving its fast self-healing property without the need for external stimuli.

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

PubMed

Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

2016-10-15

The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel Ordered Crown Ether-Containing Polyimides for Ion Conduction

NASA Technical Reports Server (NTRS)

Irvin, Jennifer A.; Stasko, Daniel; Fallis, Stephen; Guenthner, Andrew J.; Webber, Cynthia; Blackwell, John; Chvalun, Sergei N.

2003-01-01

We report the synthesis and characterization of thermally-stable polyimides for use as battery and fuel cell electrolyte membranes. Dianhydrides used were 1,4,5,8- naphthalenetetracarboxylic dianhydride and/or 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Diamines used were anti-4,4-diaminodibenzo-l8-crown-6, 4,4'- diaminodibenzo-24-crown-8, 2,2-bis(4-aminophenyl)hexafluoropropane, and/or 2,5- diaminobenzenesulfonic acid. The polymers were characterized using electrochemical impedance spectroscopy (EIS), thermal analysis and X-ray diffraction. Polymers containing the hexafluoroisopropylidene (HFIP) group were soluble in common organic solvents, while polymers without the HFIP group were very poorly soluble. Sulfonation yields polymers that are sparingly soluble in aqueous base and/or methanol. Degree of sulfonation, determined by titration, was between one and three sulfonate groups per repeat unit. Proton conductivity was determined as a function of water content, with a maximum conductivity of l x 10(exp -2) per centimeter when fully hydrated. Crown ether-containing polymers exhibit a high degree of order that may be indicative of crown ether channel formation, which may facilitate Li(+) transport for use in battery membranes.

Removal of arsenic compounds from spent catecholated polymer

DOEpatents

Fish, Richard H.

1985-01-01

Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

Approach to Rapid Synthesis and Functionalization of Iron Oxide Nanoparticles for High Gene Transfection.

PubMed

Stephen, Zachary R; Dayringer, Christopher J; Lim, Josh J; Revia, Richard A; Halbert, Mackenzie V; Jeon, Mike; Bakthavatsalam, Arvind; Ellenbogen, Richard G; Zhang, Miqin

2016-03-01

Surface functionalization of theranostic nanoparticles (NPs) typically relies on lengthy, aqueous postsynthesis labeling chemistries that have limited ability to fine-tune surface properties and can lead to NP heterogeneity. The need for a rapid, simple synthesis approach that can provide great control over the display of functional moieties on NP surfaces has led to increased use of highly selective bioorthoganol chemistries including metal-affinity coordination. Here we report a simple approach for rapid production of a superparamagnetic iron oxide NPs (SPIONs) with tunable functionality and high reproducibility under aqueous conditions. We utilize the high affinity complex formed between catechol and Fe((III)) as a means to dock well-defined catechol modified polymer modules on the surface of SPIONs during sonochemical coprecipitation synthesis. Polymer modules consisted of chitosan and poly(ethylene glycol) (PEG) copolymer (CP) modified with catechol (CCP), and CCP functionalized with cationic polyethylenimine (CCP-PEI) to facilitate binding and delivery of DNA for gene therapy. This rapid synthesis/functionalization approach provided excellent control over the extent of PEI labeling, improved SPION magnetic resonance imaging (MRI) contrast enhancement and produced an efficient transfection agent.

Concentration-response data on toxicity of pyrolysis gases from some natural and synthetic polymers

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Huttlinger, N. V.

1978-01-01

Concentration-response data are presented on the toxic effects of the pyrolysis gases from some natural and synthetic polymers, using the toxicity screening test method developed at the University of San Francisco. The pyrolysis gases from wool, red oak, Douglas fir, polycaprolactam, polyether sulfone, polyaryl sulfone, and polyphenylene sulfide appeared to exhibit the concentration-response relationships commonly encountered in toxicology. Carbon monoxide seemed to be an important toxicant in the pyrolysis gases from red oak, Douglas fir, and polycaprolactam, but did not appear to have been the principal toxicant in the pyrolysis gases from polyether sulfone and polyphenylene sulfide.

The 5-(4-Ethynylophenoxy) isophthalic chloride

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Jensen, B. J. (Inventor)

1986-01-01

Sulfone-ester polymers containing pendent ethynyl groups and a direct and multistep process for preparing them are disclosed. The multistep process involves the conversion of a pendent bromo group to the ethynyl group while the direct route involves reating hydroxy-terminated sulfone oligomer or polymers with a stoichiometric amount of 5-(4-ethynylphenoxy) isophthaloyl chloride. The 5-(4-ethynylphenoxy) isophthaloyl chloride and the process for preparing it are also disclosed.

Characterization of Highly Sulfonated SIBS Polymer Partially Neutralized With Mg(+2) Cations

DTIC Science & Technology

2008-08-01

protective clothing, block copolymer ionomer membranes emerge. They are highly ordered sequence of both ionic and nonionic blocks, in which the ionic ...incorporated into the ionic polymer. Fourier-transform infrared spectroscopy results revealed that a significant amount of ordering occurred as a result on...increasing Mg content. This band indicates Mg complexation formed when two or more sulfonate groups ionically bonded to the Mg+2 cation

CORROSION PREVENTION OF COLD ROLLED STEEL USING WATER DISPERSIBLE LIGNOSULFONIC ACID DOPED POLYANILINE

NASA Technical Reports Server (NTRS)

Viswanathan, Tito (Inventor)

2005-01-01

The invention provides coatings useful for preventing corrosion of metals. The coatings comprise a film-forming resin and conductive polymers comprising linearly conjugated pi-systems and residues of sulfonated lignin or a sulfonated polyflavonoid or derivatives of sulfonated lignin or a sulfonated polyflavonoid. The invention also provides a latex formulation of the coatings, and articles of manufacture comprising a metal substrate and a coating in contact with the metal substrate.

Morphology and Proton Transport in Sulfonated Block Copolymer and Mesoporous Polymer Electrolyte Membranes

NASA Astrophysics Data System (ADS)

Chen, Chelsea; Wong, David; Beers, Keith; Balsara, Nitash

2013-03-01

In an effort to understand the fundamentals of proton transport in polymer electrolyte membranes (PEMs), we have developed a series of poly(styrene-b-ethylene-b-styrene) (SES) membranes. The SES membranes were subsequently sulfonated to yield proton conducting S-SES membranes. We examine the effects of sulfonation level, temperature and thermal history on the morphology of S-SES membranes in both dry and hydrated states. The effects of these parameters on water uptake and proton transport characteristics of the membranes are also examined. Furthermore, building upon the strategy we deployed in sulfonating the SES membranes, we fabricated mesoporous S-SES membranes, with pores lined up with the proton conducting channels. These membranes have three distinct phases: structural block, proton-conducting block, and void. We examine the effects of pore size, domain structure and sulfonation level on water uptake and proton conductivity of the mesoporous PEMs at different temperatures. This work is funded by Department of Energy.

Silk Fibroin Aqueous-Based Adhesives Inspired by Mussel Adhesive Proteins.

PubMed

Burke, Kelly A; Roberts, Dane C; Kaplan, David L

2016-01-11

Silk fibroin from the domesticated silkworm Bombyx mori is a naturally occurring biopolymer with charged hydrophilic terminal regions that end-cap a hydrophobic core consisting of repeating sequences of glycine, alanine, and serine residues. Taking inspiration from mussels that produce proteins rich in L-3,4-dihydroxyphenylalanine (DOPA) to adhere to a variety of organic and inorganic surfaces, the silk fibroin was functionalized with catechol groups. Silk fibroin was selected for its high molecular weight, tunable mechanical and degradation properties, aqueous processability, and wide availability. The synthesis of catechol-functionalized silk fibroin polymers containing varying amounts of hydrophilic polyethylene glycol (PEG, 5000 g/mol) side chains was carried out to balance silk hydrophobicity with PEG hydrophilicity. The efficiency of the catechol functionalization reaction did not vary with PEG conjugation over the range studied, although tuning the amount of PEG conjugated was essential for aqueous solubility. Adhesive bonding and cell compatibility of the resulting materials were investigated, where it was found that incorporating as little as 6 wt % PEG prior to catechol functionalization resulted in complete aqueous solubility of the catechol conjugates and increased adhesive strength compared with silk lacking catechol functionalization. Furthermore, PEG-silk fibroin conjugates maintained their ability to form β-sheet secondary structures, which can be exploited to reduce swelling. Human mesenchymal stem cells (hMSCs) proliferated on the silks, regardless of PEG and catechol conjugation. These materials represent a protein-based approach to catechol-based adhesives, which we envision may find applicability as biodegradable adhesives and sealants.

Genipin-crosslinked catechol-chitosan mucoadhesive hydrogels for buccal drug delivery.

PubMed

Xu, Jinke; Strandman, Satu; Zhu, Julian X X; Barralet, Jake; Cerruti, Marta

2015-01-01

Drug administration via buccal mucosa is an attractive drug delivery strategy due to good patient compliance, prolonged localized drug effect, and avoidance of gastrointestinal drug metabolism and first-pass elimination. Buccal drug delivery systems need to maintain an intimate contact with the mucosa lining in the wet conditions of the oral cavity for long enough to allow drug release and absorption. For decades, mucoadhesive polymers such as chitosan (CS) and its derivatives have been explored to achieve this. In this study, inspired by the excellent wet adhesion of marine mussel adhesive protein, we developed a buccal drug delivery system using a novel catechol-functionalized CS (Cat-CS) hydrogel. We covalently bonded catechol functional groups to the backbone of CS, and crosslinked the polymer with a non-toxic crosslinker genipin (GP). We achieved two degrees of catechol conjugation (9% and 19%), forming Cat9-CS/GP and Cat19-CS/GP hydrogels, respectively. We confirmed covalent bond formation during the catechol functionalization and GP crosslinking during the gel formation. The gelation time and the mechanical properties of Cat-CS hydrogels are similar to those of CS only hydrogels. Catechol groups significantly enhanced mucoadhesion in vitro (7 out of the 10 Cat19-CS hydrogels were still in contact with porcine mucosal membrane after 6 h, whereas all of the CS hydrogels lost contact after 1.5 h). The new hydrogel systems sustained the release of lidocaine for about 3 h. In-vivo, we compared buccal patches made of Cat19-CS/GP and CS/GP adhered to rabbit buccal mucosa. We were able to detect lidocaine in the rabbit's serum at concentration about 1 ng/ml only from the Cat19-CS patch, most likely due to the intimate contact provided by mucoadhesive Cat19-CS/GP systems. No inflammation was observed on the buccal tissue in contact with any of the patches tested. These results show that the proposed catechol-modified CS hydrogel is a promising mucoadhesive and biocompatible hydrogel system for buccal drug delivery. Copyright © 2014 Elsevier Ltd. All rights reserved.

Catechol-Cation Synergy in Wet Adhesive Materials

NASA Astrophysics Data System (ADS)

Maier, Gregory Peter

In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is impaired by high salt, pH, and hydration. However, mussels have evolved effective strategies for wet adhesion despite these impediments. Inspection of mussel foot proteins (Mfps) provides insights into adhesive adaptations. Catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues are present in high mole percent in the interfacial Mfps. The siderophore cyclic trichrysobactin also contains high mole percent of catechol and lysine and serves as a simplified mimic of Mfps. This work is focused on use of Mfp-mimetic siderophores and synthetic siderophore analogs as model systems for dissecting the chemical and physical interactions that enable wet adhesion. Variation in number and identity of functional groups appended to the synthetic siderophore analogs allows identification of the specific contributions of those functional groups to wet adhesion. Both catechol and amine functional groups are critical to strong wet adhesion. The primary amine of lysine and catechol cooperatively displace interfacial hydration and bind to the underlying substrate. Variation in the amine identity as well as the amine to catechol ratio within siderophore analogs also has a significant impact on wet adhesive performance. Catechol undergoes a pH-dependent autoxidation in which higher pH leads to faster oxidation by dioxygen. This oxidation abolishes all adhesion of Mfps to mica by pH 7.5, yet many applications of synthetic wet adhesives require adhesion at physiological or oceanic pH. A better understanding of catechol redox chemistry is critical to the design of wet adhesives. To this end, the pH-dependent autoxidation of catechol and substituted catechols was investigated and results are consistent with a mechanism in which O2 oxidizes both the mono-deprotonated and di-deprotonated catechol. A linear Hammett correlation for the pH-independent second order rate constants for catechol autoxidation indicates that catechols become resistant to autoxidation when functionalized with electron withdrawing groups and more susceptible to autoxidation when functionalized with electron donating groups. Analysis of substituent effects through Hammett correlation allows for selection of functionalized catechols with redox properties ideally suited for a given application.

Quasi-monodimensional polyaniline nanostructures for enhanced molecularly imprinted polymer-based sensing.

PubMed

Berti, Francesca; Todros, Silvia; Lakshmi, Dhana; Whitcombe, Michael J; Chianella, Iva; Ferroni, Matteo; Piletsky, Sergey A; Turner, Anthony P F; Marrazza, Giovanna

2010-10-15

Recent advances in nanotechnology have allowed significant progress in utilising cutting-edge techniques associated with nanomaterials and nano-fabrication to expand the scope and capability of biosensors to a new level of novelty and functionality. The aim of this work was the development and characterisation of conductive polyaniline (PANI) nanostructures for applications in electrochemical biosensing. We explore a simple, inexpensive and fast route to grow PANI nanotubes, arranged in an ordered structure directly on an electrode surface, by electrochemical polymerisation using alumina nanoporous membranes as a 'nano-mould'. The deposited nanostructures have been characterised electrochemically and morphologically prior to grafting with a molecularly imprinted polymer (MIP) receptor in order to create a model sensor for catechol detection. In this way, PANI nanostructures resulted in a conductive nanowire system which allowed direct electrical connection between the electrode and the synthetic receptor (MIP). To our knowledge, this is the first example of integration between molecularly imprinted polymers and PANI nanostructured electrodes. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor for catechol detection that was previously developed. A significantly lower limit of detection for catechol has been obtained (29 nM, one order of magnitude), thus demonstrating that the nanostructures are capable of improving the analytical performance of the sensor. Copyright © 2010 Elsevier B.V. All rights reserved.

Flexible and conductive waste tire-derived carbon/polymer composite paper as pseudocapacitive electrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naskar, Amit K.; Paranthaman, Mariappan Parans; Boota, Muhammad

A method of making a supercapacitor from waste tires, includes the steps of providing rubber pieces and contacting the rubber pieces with a sulfonation bath to produce sulfonated rubber; pyrolyzing the sulfonated rubber to produce a tire-derived carbon composite comprising carbon black embedded in rubber-derived carbon matrix comprising graphitized interface portions; activating the tire-derived carbon composite by contacting the tire-derived carbon composite with a specific surface area-increasing composition to increase the specific surface area of the carbon composite to provide an activated tire-derived carbon composite; and, mixing the activated tire-derived carbon composite with a monomer and polymerizing the monomer tomore » produce a redox-active polymer coated, activated tire-derived carbon composite. The redox-active polymer coated, activated tire-derived carbon composite can be formed into a film. An electrode and a supercapacitor are also disclosed.« less

Membrane separation of hydrocarbons

DOEpatents

Chang, Y. Alice; Kulkarni, Sudhir S.; Funk, Edward W.

1986-01-01

Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture through a polymeric membrane. The membrane which is utilized to effect the separation comprises a polymer which is capable of maintaining its integrity in the presence of hydrocarbon compounds and which has been modified by being subjected to the action of a sulfonating agent. Sulfonating agents which may be employed will include fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, etc., the surface or bulk modified polymer will contain a degree of sulfonation ranging from about 15 to about 50%. The separation process is effected at temperatures ranging from about ambient to about 100.degree. C. and pressures ranging from about 50 to about 1000 psig.

Synthesis and Characterization of Sulfonated Graphene Oxide Nanofiller for Polymer Electrolyte Membrane

NASA Astrophysics Data System (ADS)

Ch'ng, Y. Y.; Loh, K. S.; Daud, W. R. W.; Mohamad, A. B.

2016-11-01

In this study, sulfonated graphene oxide (SGO) nanocomposite were produced as potential nanofiller to improve the properties of polymer electrolyte membrane (PEM) for fuel cell applications. The GO is produced by modified Hummers's method and the as-synthesized GO was used to prepare SGO with three distinctive precursors, namely 3- mercaptomethoxysilane (MPTMS), sulfanilic acid (SA) and butane sultone (BS). The SGO samples were characterized with several physical characterization techniques (XRD, FTIR, SEM-EDX and XPS) to provide the insights into the morphology; the state of homogenization; the crystallography and the functional groups. The experimental result indicated that the sulfonic acid group has been successfully incorporated with GO and can be used as filler in PEM.

Self-assembled multilayers and photoluminescence properties of a new water-soluble poly(para-phenylene)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, X.; Li, D.; Luett, M.

1998-07-01

This paper reports the synthesis and characterizations of a new water-soluble poly(paraphenylene) (PPP) and its applications in preparing self-assembled multi-layer films. This new water-soluble conducting polymer was prepared through the sulfonation reaction of poly(p-quarterphenylene-2,2{prime}-dicarboxylic acid). The incorporation of sulfonate groups has dramatically improved PPP's solubility in water at a wide pH range, whereas previous PPP is only slightly soluble in basic solutions. Dilute aqueous solutions of this polymer with acidic, neutral or basic pH emit brilliant blue light while irradiated with UV light. The sulfonated PPP emits from 350 nm to 455 nm with a maximum intensity at 380 nm.more » Self-assembled multilayers of this sulfonated PPP were constructed with a positively charged polymer poly(diallyl dimethyl ammonium chloride) and characterized with various surface analyses. Conductive (RuO{sub 2} and ITO), semiconductive (Si wafer), and non-conductive (SiO{sub 2}) substrates were used in the preparation of self-assembled multilayers. Electrical, optical and structural properties of these novel self-assembled thin films will be discussed.« less

Self-assembled multilayers and photoluminescence properties of a new water-soluble poly(para-phenylene)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, X.; Li, D.Q.; Luett, M.

1998-03-01

This paper reports the synthesis and characterizations of a new water-soluble poly(para-phenylene) (PPP) and its applications in preparing self-assembled multilayer films. This new water-soluble conducting polymer was prepared through the sulfonation reaction of poly(p-quarterphenylene-2,2{prime}-dicarboxylic acid). The incorporation of sulfonate groups has dramatically improved PPP`s solubility in water at a wide pH range, whereas previous PPP is only slightly soluble in basic solutions. Dilute aqueous solutions of this polymer with acidic, neutral or basic pH emit brilliant blue light while irradiated with UV light. The sulfonated PPP emits from 350 nm to 455 nm with a maximum intensity at 380 nm.more » Self-assembled multilayers of this sulfonated PPP were constructed with a positively charged polymer poly(diallyl dimethyl ammonium chloride) and characterized with various surface analyses. Conductive (RuO{sub 2} and ITO), semiconductive (Si wafer), and non-conductive (SiO{sub 2}) substrates were used in the preparation of self-assembled multilayers. Electrical, optical and structural properties of these novel self-assembled thin films will be discussed.« less

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... sulfonic acid. The Chemical Abstracts Service name of this polymer is ethane-sulfonic acid, 2-[1-[difluoro... temperatures not exceeding 70° (158 °F). (2) Maximum thickness of the copolymer membrane is 0.007 inch (0.017...

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Code of Federal Regulations, 2013 CFR

2013-04-01

... sulfonic acid. The Chemical Abstracts Service name of this polymer is ethane-sulfonic acid, 2-[1-[difluoro... temperatures not exceeding 70° (158 °F). (2) Maximum thickness of the copolymer membrane is 0.007 inch (0.017...

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... sulfonic acid. The Chemical Abstracts Service name of this polymer is ethane-sulfonic acid, 2-[1-[difluoro... temperatures not exceeding 70° (158 °F). (2) Maximum thickness of the copolymer membrane is 0.007 inch (0.017...

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Code of Federal Regulations, 2012 CFR

2012-04-01

... sulfonic acid. The Chemical Abstracts Service name of this polymer is ethane-sulfonic acid, 2-[1-[difluoro... temperatures not exceeding 70° (158 °F). (2) Maximum thickness of the copolymer membrane is 0.007 inch (0.017...

Long-lasting solid-polymer electrolytic hygrometer

NASA Technical Reports Server (NTRS)

Lawson, D. D.

1978-01-01

Device consists of hollow tube node of oxidation-resistant sulfonated fluorocarbon polymer. Tube absorbs moisture from air passing across inner and outer surfaces, causing change in polymer conductance. Change is related to change in water content in gas sample.

Electrical and Environmental Studies of Conduction Polymers.

DTIC Science & Technology

1986-01-17

Carbonate), 0.25M Tetrabutylammonium hexafluorophosphate (Bu4 NPF 6 )/THF, and 0.25M Lithium Trifluoromethyl sulfonate (LiCF3 SO 3)frHF. Lithium ...processible polymeric component Other anions commonly used in synthesizing polypyrrole, namely, tetrafluoroborate, hexafluorophosphate rifluoromethyl...are perchlorate (CI0 4 "), tetrafluoroborate (BF 4 "), trifluoromethyl sulfonate (CF3 SO"), hexafluorophosphate (PF6 ") and p-toluene sulfonate (PTS

Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

1979-01-01

The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

Special Issue on Powering the Future Force: New Power & Energy Technologies for the Warfighter (AMMTIAC Quarterly, Volume 4, Number 1 / WSTIAC Quarterly, Volume 9, Number 1)

DTIC Science & Technology

2009-04-27

an aromatic acidic polymer such as SPEEK or SPSf. Figure 5 shows four basic polymers in which benzimidazole (BIm), amino- benzimidazole (ABIm...Z., A. Manthiram, and M. D. Guiver, “Blend Membranes Based on Sulfonated Polyetheretherketone and Polysulfone Bearing Benzimidazole Side Groups for...Sulfonated Poly(ether ether ketone) and Polysulfone Bearing Benzimidazole Side Groups for Direct Methanol Fuel Cells,” Electrochemical and Solid State Letters

A new hypercrosslinked supermicroporous polymer, with scope for sulfonation, and its catalytic potential for the efficient synthesis of biodiesel at room temperature.

PubMed

Bhunia, Subhajit; Banerjee, Biplab; Bhaumik, Asim

2015-03-25

We have designed a new hypercrosslinked supermicroporous polymer (HMP-1) with a BET surface area of 913 m(2) g(-1) by FeCl3 via a catalyzed Friedel-Crafts alkylation reaction between carbazole and α,α'-dibromo-p-xylene. Upon sulfonation HMP-1 yielded a very efficient solid acid catalyst for the production of biodiesels via esterification/transesterification of free fatty acids (FFA)/esters at room temperature.

Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

DOE PAGES

Roach, David J.; Dou, Shichen; Colby, Ralph H.; ...

2012-01-06

Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T 1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T 1 values along with the presence of minima in T 1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similarmore » activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.« less

A Study of influence on sulfonated TiO2-Poly (Vinylidene fluoride-co-hexafluoropropylene) nano composite membranes for PEM Fuel cell application

NASA Astrophysics Data System (ADS)

kumar, K. Selva; Rajendran, S.; Prabhu, M. Ramesh

2017-10-01

The present work describes the sulfonated Titania directly blended with Poly (Vinylidene fluoride-co-hexafluoropropylene) as a host polymer by solvent casting technique for PEM fuel cell application. Characterization studies such as FT-IR, SEM, EDX, AFM, Proton conductivity, contact angle measurement, IEC, TG, water uptake, tensile strength were performed by for synthesized proton conducting polymer electrolytes. The maximum proton conductivity value was found to be 3.6 × 10-3S/cm for 25 wt% sulfonated Titania based system at 80 °C. The temperature dependent proton conductivity of the polymer electrolyte follows an Arrhenius relationship. Surface morphology of the composite membranes was investigated by tapping mode. Thermal stability of the system was studied by TG analysis. The fabricated composite membranes with high proton conductivity, good water uptake and IEC parameters exhibited a maximum fuel cell power density of 85 Mw/cm2for PEM fuel cell application.

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Putri, Zufira; Arcana, I. Made

2014-03-01

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO2 are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes to be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO2 compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO2 blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM).

Deciphering the Role of Sulfonated Unit in Heparin-Mimicking Polymer to Promote Neural Differentiation of Embryonic Stem Cells.

PubMed

Lei, Jiehua; Yuan, Yuqi; Lyu, Zhonglin; Wang, Mengmeng; Liu, Qi; Wang, Hongwei; Yuan, Lin; Chen, Hong

2017-08-30

Glycosaminoglycans (GAGs), especially heparin and heparan sulfate (HS), hold great potential for inducing the neural differentiation of embryonic stem cells (ESCs) and have brought new hope for the treatment of neurological diseases. However, the disadvantages of natural heparin/HS, such as difficulty in isolating them with a sufficient amount, highly heterogeneous structure, and the risk of immune responses, have limited their further therapeutic applications. Thus, there is a great demand for stable, controllable, and well-defined synthetic alternatives of heparin/HS with more effective biological functions. In this study, based upon a previously proposed unit-recombination strategy, several heparin-mimicking polymers were synthesized by integrating glucosamine-like 2-methacrylamido glucopyranose monomers (MAG) with three sulfonated units in different structural forms, and their effects on cell proliferation, the pluripotency, and the differentiation of ESCs were carefully studied. The results showed that all the copolymers had good cytocompatibility and displayed much better bioactivity in promoting the neural differentiation of ESCs as compared to natural heparin; copolymers with different sulfonated units exhibited different levels of promoting ability; among them, copolymer with 3-sulfopropyl acrylate (SPA) as a sulfonated unit was the most potent in promoting the neural differentiation of ESCs; the promoting effect is dependent on the molecular weight and concentration of P(MAG-co-SPA), with the highest levels occurring at the intermediate molecular weight and concentration. These results clearly demonstrated that the sulfonated unit in the copolymers played an important role in determining the promoting effect on ESCs' neural differentiation; SPA was identified as the most potent sulfonated unit for copolymer with the strongest promoting ability. The possible reason for sulfonated unit structure as a vital factor influencing the ability of the copolymers may be attributed to the difference in electrostatic and steric hindrance effect. The synthetic heparin-mimicking polymers obtained here can offer an effective alternative to heparin/HS and have great therapeutic potential for nervous system diseases.

Thermoplastic polymers for improved fire safety

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.; Hilado, C. J.

1976-01-01

The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use and others being considered for use in aircraft interiors are described. The properties studied included (1) thermomechanical properties such as glass transition and melt temperature, (2) changes in polymer enthalpy by differential scanning calorimetry, (3) thermogravimetric analysis in anaerobic and oxidative environments, (4) oxygen index, (5) smoke evolution, (6) relative toxicity of the volatile products of pyrolysis, and (7) selected physical properties. The generic polymers that were evaluated included: acrylonitrile butadiene styrene, bisphenol A polycarbonate, 9,9 bis (4-hydroxyphenyl) fluorene polycarbonatepoly (dimethyl siloxane) block polymer, phenolphthalein bisphenol A polycarbonate, phenolphthalein polycarbonate, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone, chlorinated polyvinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters, including molding characteristics of some of the advanced polymers, are described. Test results and relative ranking of some of the flammability, smoke, and toxicity properties are presented.

Intercalation of sulfonated melamine formaldehyde polycondensates into a hydrocalumite LDH structure

NASA Astrophysics Data System (ADS)

von Hoessle, F.; Plank, J.; Leroux, F.

2015-05-01

A series of sulfonated melamine formaldehyde (SMF) polycondensates possessing different anionic charge amounts and molecular weights was synthesized and incorporated into a hydrocalumite type layered double hydroxide structure using the rehydration method. For this purpose, tricalcium aluminate was dispersed in water and hydrated in the presence of these polymers. Defined inorganic-organic hybrid materials were obtained as reaction products. All SMF polymers tested intercalated readily into the hydrocalumite structure, independent of their different molecular weights (chain lengths) and anionic charge amounts. X-ray diffraction revealed typical patterns for weakly ordered, highly polymer loaded LDH materials which was confirmed via elemental analysis and thermogravimetry. IR spectroscopy suggests that the SMF polymers are interleaved between the [Ca2Al(OH)6]+ main sheets via electrostatic interaction, and that no chemical bond between the host matrix and the guest anion is formed. The SMF polymers well ensconced within the LDH structure exhibit significantly slower thermal degradation.

Series of coordination polymers based on 4-(5-sulfo-quinolin-8-yloxy) phthalate and bipyridinyl coligands: Structure diversity and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Xun; Liu, Jing; College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022

2015-10-15

Reactions between later metal salts and conjugational N-hetrocyclic sulfonate/ carboxylic acid under the presence of bipyridyl auxiliary ligands afforded a series of manganese, nickel, zinc, silver, cadmium coordination polymers bearing with phenyl pendant arm attached to quinoline skeletons, and they have been characterized by elements analysis, thermogravimetry, infrared spectroscopy and single-crystal X-ray diffraction studying. The series of polymers show interesting structural diversity in coordination environment, dimensions and topologies. They are all built from 2-D networks constructed from metal cluster through sulfonate or carboxylate groups, as the secondary building unit (SBU). The thermalgravimetric analyses show that they display framework stabilities inmore » solid state. Variable-temperature magnetic susceptibility studies reveal the existence of antiferromagnetic interactions between adjacent Mn (II) ions in 1, and ferromagnetic interactions between Ni(II) ions for 2, respectively. The photo-luminescence properties of 3-5 have also been investigated systemically. - Highlights: • A series of coordination polymers based on later transition metal ions have been obtained. • They contain conjugational N-hetrocyclic sulfonate-carboxylic acid and bipyridyl auxiliary ligands. • They have been characterized systemically. • They exhibit structure diversity and interesting properties.« less

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

PubMed

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

Analysis of cerium-composite polymer-electrolyte membranes during and after accelerated oxidative-stability test

NASA Astrophysics Data System (ADS)

Shin, Dongwon; Han, Myungseong; Shul, Yong-Gun; Lee, Hyejin; Bae, Byungchan

2018-02-01

The oxidative stability of membranes constructed from a composite of pristine sulfonated poly(arylene ether sulfone) and cerium was investigated by conducting an accelerated oxidative-stability test at the open-circuit voltage (OCV). The membranes were analyzed in situ through OCV and impedance measurements, cyclic voltammetry, and linear-sweep voltammetry to monitor the electrochemical properties during the stability test. Although the high-frequency resistance of a composite membrane was slightly higher than that of a pristine membrane because of the exchange of protons from the sulfonic acid with cerium ions, the composite membrane maintained its potential for much longer than the pristine membrane. The effect of the cerium ions as radical scavengers was confirmed by analyzing the drain water and chemical structure after operation. These post-operation analyses confirmed that cerium ions improved the oxidative stability of the hydrocarbon-based polymer during fuel-cell operation. It is clear that the cerium-based radical scavengers prevented chemical degradation of the polymer membrane as well as the electrode in terms of hydrogen cross-over, polymer-chain scission, and the electrochemical surface area, while they rarely diffused outward from the membrane.

Thermoplastic composite matrices with improved solvent resistance

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

1984-01-01

In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.

Development of Ultrafiltration Membrane-Separation Technology for Energy-Efficient Water Treatment and Desalination Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yim, Woosoon; Bae, Chulsung

The growing scarcity of fresh water is a major political and economic challenge in the 21st century. Compared to thermal-based distillation technique of water production, pressure driven membrane-based water purification process, such as ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), can offer more energy-efficient and environmentally friendly solution to clean water production. Potential applications also include removal of hazardous chemicals (i.e., arsenic, pesticides, organics) from water. Although those membrane-separation technologies have been used to produce drinking water from seawater (desalination) and non-traditional water (i.e., municipal wastewater and brackish groundwater) over the last decades, they still have problems in ordermore » to be applied in large-scale operations. Currently, a major huddle of membrane-based water purification technology for large-scale commercialization is membrane fouling and its resulting increases in pressure and energy cost of filtration process. Membrane cleaning methods, which can restore the membrane properties to some degree, usually cause irreversible damage to the membranes. Considering that electricity for creating of pressure constitutes a majority of cost (~50%) in membrane-based water purification process, the development of new nano-porous membranes that are more resistant to degradation and less subject to fouling is highly desired. Styrene-ethylene/butylene-styrene (SEBS) block copolymer is one of the best known block copolymers that induces well defined morphologies. Due to the polarity difference of aromatic styrene unit and saturated ethylene/butylene unit, these two polymer chains self-assemble each other and form different phase-separated morphologies depending on the ratios of two polymer chain lengths. Because the surface of SEBS is hydrophobic which easily causes fouling of membrane, incorporation of ionic group (e,g, sulfonate) to the polymer is necessary to reduces fouling. Recently, sulfonated SEBS became commercially available and has been extensively explored for membrane-mediated water purification technology. The sulfonated block copolymer creates a well developed nano-sale phase-separated morphologies composed of hydrophilic domains (sulfonated polystyrene) and hydrophobic domains (polyethylene/polybutylene). The hydrophilic domains determines transport properties (water transport, salt and/or ion rejection, etc) and the hydrophobic domains provides mechanical stability of the membrane. Unfortunately, a high degree of sulfonation of SEBS induces excessive swelling and deterioration of mechanical stability of the membrane. In an effort to develop robust polymeric membrane materials for water purification technology, phosphonic acid-functionalized SEBS membranes are investigated during this report period. In compare to sulfonated polymers, the corresponding phosphonated polymers are known to swell less because of the formation of extensive hydrogen bonding networks between phosphonates. In addition to the expected better mechanical stability, phosphonated polymers has another advantage over sulfonated polymers for the use water purification membrane; each phosphonate can accommodate two ions while each sulfonate accommodates only one ion. Membrane properties (ion type, ionic density, etc) of new membranes will be studied and their separation performance will be evaluated in water purification and desalination process. Through systematic study of the relationship of chemical structure–surface property–membrane performance, we aim to better understand the nature of membrane fouling and develop more fouling-resistant water purification membranes. The basic understanding of this relationship will lead to the development of advanced membrane materials which can offer a solution to environmentally sustainable production of fresh water.« less

Corrosion prevention of cold rolled steel using water dispersible lignosulfonic acid doped polyaniline

NASA Technical Reports Server (NTRS)

Viswanathan, Tito (Inventor)

2007-01-01

The invention provides coatings useful for preventing corrosion of metals. The coatings comprise a film-forming resin and conductive polymers comprising linearly conjugated .pi.-systems and residues of sulfonated lignin or a sulfonated polyflavonoid or derivatives of solfonated lignin or a sulfonated polyflavonoid. The invention also provides a latex formulation of the coatings, and articles of manufacture comprising a metal substrate and a coating in contact with the metal substrate.

Corrosion Prevention of Cold Rolled Steel Using Water Dispersible Lignosulfonic Acid Doped Polyaniline

NASA Technical Reports Server (NTRS)

Viswanathan, Tito (Inventor)

2007-01-01

The invention provides coatings useful for preventing corrosion of metals. The coatings comprise a film-forming resin and conductive polymers comprising linearly conjugated x-systems and residues of sulfonated lignin or a sulfonated polyflavonoid or derivatives of solfonated lignin or a sulfonated polyflavonoid. The invention also provides a latex formulation of the coatings, and articles of manufacture comprising a metal substrate and a coating in contact with the metal substrate.

High temperature polymers for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Einsla, Brian Russel

Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was synthesized in order to investigate this possible advantage and to couple this with the excellent hydrolytic stability of poly(arylene ether)s. The methoxy groups were deprotected to afford reactive phenolic sites and nucleophilic substitution reactions with functional aryl sulfonates were used to prepare simple aryl or highly acidic fluorinated sulfonated copolymers. The proton conductivity and water sorption of the resulting copolymers increased with the ion exchange capacity, but changing the acidity of the sulfonic acid had no apparent effect.

Mimetic marine antifouling films based on fluorine-containing polymethacrylates

NASA Astrophysics Data System (ADS)

Sun, Qianhui; Li, Hongqi; Xian, Chunying; Yang, Yihang; Song, Yanxi; Cong, Peihong

2015-07-01

Novel methacrylate copolymers containing catechol and trifluoromethyl pendant side groups were synthesized by free radical polymerization of N-(3,4-dihydroxyphenyl)ethyl methacrylamide (DMA) and 2,2,2-trifluoroethyl methacrylate (TFME) with α,α‧-azobisisobutyronitrile (AIBN) as initiator. A series of copolymers with different content of TFME ranging from 3% to 95% were obtained by changing the molar ratio of DMA to TFME from 25:1 to 1:25. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to characterize the copolymers, which displayed a certain degree of hardness and outstanding thermostability reflected from their high glass transition temperatures. The copolymers could adhere to surfaces of glass, plastics and metals due to introduction of catechol groups as multivalent hydrogen bonding anchors. Water contact angle on the polymer films was up to 117.4°. Chemicals resistance test manifested that the polymer films possessed excellent resistance to water, salt, acid and alkali. Moreover, the polymer films displayed fair antifouling property and might be used as promising environmentally friendly marine antifouling coatings.

Thermochemical characterization of some thermoplastic materials. [flammability and toxicity properties for aircraft interiors

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.; Hilado, C. J.

1977-01-01

The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use or being considered for use in aircraft interiors are described. The properties studied included thermomechanical properties such as glass-transition and melt temperature, changes in polymer enthalpy, thermogravimetric analysis in anerobic and oxidative environments, oxygen index, smoke evolution, relative toxicity of the volatile products of pyrolysis, and selected physical properties. The generic polymers evaluated included acrylonitrile butadiene styrene, bisphenol A polycarbonate, 9,9 bis (4-hydroxyphenyl) fluorene polycarbonate-poly (dimethylsiloxane) block polymer, phenolphthalein-bisphenol A polycarbonate, phenolphthalein polycarbonate, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone, chlorinated polyvinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters, including molding characteristics of some of the advanced polymers, are described. Test results and relative rankings of some of the flammability, smoke, and toxicity properties are presented. Under these test conditions, some of the advanced polymers evaluated were significantly less flammable and toxic than or equivalent to polymers in current use.

Sulfonated polysulfone battery membrane for use in corrosive environments

DOEpatents

Arnold, Jr., Charles; Assink, Roger

1987-01-01

For batteries containing strong oxidizing electrolyte and a membrane separating two electrolyte solutions, e.g., a zinc ferricyanide battery, an improved membrane is provided comprising an oxidative resistant, conductive, ion-selective membrane fabricated from a catenated aromatic polymer having an absence of tertiary hydrogens, e.g., a sulfonated polysulfone.

Facile doping of anionic narrow-band-gap conjugated polyelectrolytes during dialysis.

PubMed

Mai, Cheng-Kang; Zhou, Huiqiong; Zhang, Yuan; Henson, Zachary B; Nguyen, Thuc-Quyen; Heeger, Alan J; Bazan, Guillermo C

2013-12-02

PCPDTBTSO3 K, an anionic, narrow-band-gap conjugated polyelectrolyte, was found to be doped after dialysis. The proposed doping mechanism involves protonation of the polymer backbone, followed by electron transfer from a neutral chain, to generate radical cations, which are stabilized by the pendant sulfonate anions. Formation of polarons is supported by spectroscopy and electrical-conductivity measurements. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Structures of Fibronectin Adsorbed on Polyelectrolyte Thin Films

NASA Astrophysics Data System (ADS)

Shin, Kwanwoo; Satija, Sushil; Fang, Xiao-Hua; Li, Bin-Quan; Nadine, Pernodet; Miriam, Rafailovich; Sokolov, Jonathan; Arach, Goldar; Roser, Steve

2002-03-01

We have shown that it is possible to form a fibrilar network of fibronectin on a polyelectrolyte polymer film whose dimensions are similar to those reported on the extra cellular matrix. The fibronectin network was observed to form only when the charge density of the polymer was in excess of the natural charge density of the cell wall. Furthermore, the self-organized fibronectin layer was much thicker than the polymer film, indicating that long ranged interaction may play a key role in the assembly process. It is therefore important to understand the structure of the polymer layer/protein interface. Here we report on a neutron reflectivity study where we explore the structure of the polyelectrolyte layer, in this case sulfonated polystyrene (PSS_x.), with varying degree of sulfonation (x<30%), as a function of sulfur content and counter ion concentration. These results are then correlated with systemic study of the adsorption and the multilayer formation of fibronectin as a function of incubation time for various sulfonation levels of PSS_x. Furthermore, the surface charge on the substrates can be strongly influenced by the presence of salt ions, it is important to understand changes due to electrostatic interactions occurring in the various salt conditions. Complementary X-ray reflection was used to determine the salt density profile associating with the internal ionic polymer matrix. This work was funded in part of the NSF-MRSEC program.

Synthesis and Characterization of Hydrophilic-Hydrophobic Poly(Arylene Ether Sulfone) Random and Segmented Copolymers for Membrane Applications

NASA Astrophysics Data System (ADS)

Nebipasagil, Ali

Poly(arylene ether sulfone)s are high-performance engineering thermoplastics that have been investigated extensively over the past several decades due to their outstanding mechanical properties, high glass transition temperatures (Tg), solvent resistance and exceptional thermal, oxidative and hydrolytic stability. Their thermal and mechanical properties are highly suited to a variety of applications including membrane applications such as reverse osmosis, ultrafiltration, and gas separation. This dissertation covers structure-property-performance relationships of poly(arylene ether sulfone) and poly(ethylene oxide)-containing random and segmented copolymers for reverse osmosis and gas separation membranes. The second chapter of this dissertation describes synthesis of disulfonated poly(arylene ether sulfone) random copolymers with oligomeric molecular weights that contain hydrophilic and hydrophobic segments for thin film composite (TFC) reverse osmosis membranes. These copolymers were synthesized and chemically modified to obtain novel crosslinkable poly(arylene ether sulfone) oligomers with acrylamide groups on both ends. The acrylamideterminated oligomers were crosslinked with UV radiation in the presence of a multifunctional acrylate and a UV initiator. Transparent, dense films were obtained with high gel fractions. Mechanically robust TFC membranes were prepared from either aqueous or water-methanol solutions cast onto a commercial UDELRTM foam support. This was the first example that utilized a water or alcohol solvent system and UV radiation to obtain reverse osmosis TFC membranes. The membranes were characterized with regard to composition, surface properties, and water uptake. Water and salt transport properties were elucidated at the department of chemical engineering at the University of Texas at Austin. The gas separation membranes presented in chapter three were poly(arylene ether sulfone) and poly(ethylene oxide) (PEO)-containing polyurethanes. Poly(arylene ether sulfone) copolymers with controlled molecular weights were synthesized and chemically modified to obtain poly(arylene ether sulfone) polyols with aliphatic hydroxyethyl terminal functionality. The hydroxyethyl-terminated oligomers and a,u-hydroxy-terminated PEO were chain extended with a diisocyanate to obtain polyurethanes. Compositions with high poly(arylene ether sulfone) content relative to the hydrophilic PEO blocks were of interest due to their mechanical integrity. The membranes were characterized to analyze their compositions, thermal and mechanical properties, water uptake, and molecular weights. These membranes were also evaluated by collaborators at the University of Texas at Austin to explore single gas transport properties. The results showed that both polymer and transport properties closely related to PEO-content. The CO2/CH4 gas selectivity of our membranes were improved from 25 to 34 and the CO2/N2 gas selectivity nearly doubled from 25 to 46 by increasing PEO-content from 0 to 30 wt.% in polyurethanes. Chapter four also focuses on polymers for gas separation membranes. Disulfonated poly(arylene ether sulfone) and poly(ethylene oxide)-containing polyurethanes were synthesized for potential applications as gas separation membranes. Disulfonated polyols containing 20 and 40 mole percent of disulfonated repeat units with controlled molecular weights were synthesized. Poly(arylene ether sulfone) polyols and alpha,o-hydroxy-terminated poly(ethylene oxide) were subsequently chain extended with a diisocyanate to obtain polyurethanes. Thermal and mechanical characterization revealed that the polyurethanes had a phase-mixed complex morphology.

Titania Deposition on PMR-15

NASA Technical Reports Server (NTRS)

Meador, Mary B.; Sutter, James K.; Pizem, Hillel; Gershevitz, Olga; Goffer, Yossi; Frimer, Aryeh A.; Sukenik, Chaim N.; Sampathkumaran, Uma; Milhet, Xavier; McIlwain, Alan

2005-01-01

The formation, degree of crystallinity and adherence of dense titania (TiO2) thin film coatings on a high-temperature polyimide resin (PMR-15) can be influenced by the chemical composition of the polymer surface. Furthermore, solution deposition conditions can be adjusted to provide additional control over the morphology and crystallinity of the titania films. Recipes for solution-based titania deposition that used a slowly-hydrolyzing titanium fluoride salt in the presence of boric acid as a fluoride scavenger allowed growth of films up to 750 nm thick in 22 h. By adjusting solution pH and temperature, either amorphous titania or oriented crystalline anatase films could be formed. Surface sulfonate groups enhance the adhesion of solution-deposited oxide thin film coatings. While most sulfonation procedures severely damaged the PMR-15 surface, the use of chlorosulfonic acid followed by hydrolysis of the installed chlorosulfonyl groups provided effective surface sulfonation without significant surface damage. In some cases, the oxide deposition solution caused partial hydrolysis of the polymer surface, which itself was sufficient to allow adhesion of the titania film through chelation of titanium ions by exposed benzoic acid groups on the polymer surface.

Hydrogen-bonded structures from adamantane-based catechols

NASA Astrophysics Data System (ADS)

Kawahata, Masatoshi; Matsuura, Miku; Tominaga, Masahide; Katagiri, Kosuke; Yamaguchi, Kentaro

2018-07-01

Adamantane-based bis- and tris-catechols were synthesized to examine the effect of hydrogen bonds on the arrangement and packing of the components in the crystalline state. Single-crystal X-ray crystallographic analysis revealed that hydrogen bonds formed by the hydroxyl groups of catechol groups play essential roles in the production of various types of unique structures. 1,3-Bis(3,4-dihydroxyphenyl)adamantane (1) provided hydrogen-bonded network structures composed of helical chains in crystal from chloroform/methanol, and layer structures in crystal from ethyl acetate/hexane. The complexation of 1 with 1,3,5-trinitrobenzene or 1,2,4,5-tetracyanobenzene resulted in the formation of co-crystals, respectively. One-dimensional hydrogen-bonded structures were constructed from the adamantane-based molecules, which participated in charge-transfer interactions with guests. 1,3,5-Tris(3,4-dihydroxyphenyl)adamantane also afforded crystal, and the components were assembled into infinite polymers.

21 CFR 173.21 - Perfluorinated ion exchange membranes.

Code of Federal Regulations, 2014 CFR

2014-04-01

... treated to hydrolyze the sulfonyl fluoride group to the sulfonic acid. The Chemical Abstracts Service name of this polymer is ethane-sulfonic acid, 2-[1-[difluoro-[(tri-fluoro-ethenyl)oxy]-methyl]-1,2,2,2... used in contact with all types of liquid foods at temperatures not exceeding 70° (158 °F). (2) Maximum...

Assessment of relative flammability and thermochemical properties of some thermoplastic materials

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1978-01-01

The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use and others being considered for use in aircraft interiors are described. The properties studied included (1) thermal mechanical properties such as glass transition and melt temperature, (2) changes in polymer enthalpy by differential scanning calorimetry, (3) thermogravimetric analysis in an anaerobic and oxidative environment, (4) oxygen index, (5) smoke evolution, (6) relative toxicity of the volatile products of pyrolysis, and (7) selected physical properties. The generic polymers which were evaluated included: acrylonitrile-butadiene-styrene, bisphenol A polycarbonate, bisphenol fluorenone carbonatedimethylsiloxane block polymer, phenolphthalein-bisphenol A polycarbonate, phenolphthalein polycarbonate, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone, chlorinated polyvinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters including molding characteristics of some of the advanced polymers are described. Test results and relative rankings of some of the flammability, smoke and toxicity properties are presented.

Characterization of flammability properties of some thermoplastic and thermoset resins. [for aircraft interiors

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1978-01-01

The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included epoxy, bismaleimide, a modified phenolic and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

Water-soluble conductive polymers

DOEpatents

Aldissi, Mahmoud

1989-01-01

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Water-soluble conductive polymers

DOEpatents

Aldissi, Mahmoud

1990-01-01

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Water-soluble conductive polymers

DOEpatents

Aldissi, M.

1988-02-12

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Putri, Zufira, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO{sub 2} are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes tomore » be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO{sub 2} compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO{sub 2} blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM)« less

Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis

2015-08-28

Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C,more » except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.« less

Fire-retardant epoxy polymers

NASA Technical Reports Server (NTRS)

Akawie, R. I.; Bilow, N.; Giants, T. W.

1978-01-01

Phosphorus atoms in molecular structure of epoxies make them fire-retardant without degrading their adhesive strength. Moreover, polymers are transparent, unlike compounds that contain arsenic or other inorganics. They have been used to bond polyvinylfluoride and polyether sulfone films onto polyimide glass laminates.

Degradation Kinetics of Grape Skin and Seed Proanthocyanidins in a Model Wine System

USDA-ARS?s Scientific Manuscript database

Catechin (monomer), purified grape skin proanthocyanidin (polymer), and purified grape seed proanthocyanidin underwent monitored accelerated oxidation under continuous oxygenation and UV light, at a constant 20 degrees C. Compounds were dissolved in model wine solutions with (and without) catechol. ...

Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

NASA Astrophysics Data System (ADS)

Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

2015-03-01

As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

Small Angle Neutron Scattering (SANS) Characterization of Electrically Conducting Polyaniline Nanofiber/Polyimide Nanocomposites

DTIC Science & Technology

2011-10-25

range, neither the D-B nor the IPL model could be used to characterize the size and shape of all PANI-0.5-CSA (polyaniline camphor sulfonic acid doped...be used to characterize the size and shape of all PANI-0.5-CSA (polyaniline camphor sulfonic acid doped polymer)/polyimide blend systems. At 1 and 2

Characterization of the Physicochemical Properties of β-Cyclodextrin-Divinyl Sulfone Polymer Carrier-Bile Acid Systems.

PubMed

Mohamed, Mohamed H; Wang, Chen; Peru, Kerry M; Headley, John V; Wilson, Lee D

2017-08-07

Herein, we report on the systematic design and characterization of cross-linked polymer carriers containing β-cyclodextrin (β-CD) and divinyl sulfone (DVS). The polymer carriers were prepared at variable feed ratios (β-CD-DVS; 1:1, 1:2, 1:3, and 1:6) and characterized using spectroscopy (IR, 1 H solution NMR, and 13 C CP-MAS solids NMR spectroscopy), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and a dye decolorization method using phenolphthalein. Uptake studies were carried out at pH 9.00 for the polymer carriers using single component bile acids (cholic acid, deoxycholic acid, glycodeoxycholic acid, and taurodeoxycholic acid). Equilibrium uptake results were evaluated by the Langmuir isotherm model where variable equilibrium parameters were related to the relative apolar character of the bile acid. The Langmuir model yields a carrier/bile acid binding affinity of ∼10 3 M -1 where the lipophilic inclusion sites of the polymer play a prominent role, while the DVS linker framework sites have a lower adsorption affinity, in accordance with the greater hydrophilic character of such sites.

Patents on Membranes Based on Non-Fluorinated Polymers for Vanadium Redox Flow Batteries.

PubMed

Choi, So-Won; Kim, Tae-Ho; Cha, Sang-Ho

2017-07-10

Vanadium redox flow batteries (VRFBs) have received considerable attention as large-scale electrochemical energy storage systems. In particular, VRFBs offer a higher power and energy density than other RFBs and mitigate undesirable performance fading, such as inevitable ion crossover, because of the unique advantage that only the vanadium ion is employed as the active species in the two electrolytes. The key constituent of VRFBs is a separator to conduct protons and prevent cross-mixing of the positive and negative electrolytes. For this purpose, ion exchange membranes like sulfonated polymer membranes can be used. Although this type of membrane does not have ion exchange groups, it can achieve an ion exchange capacity by the formation of pores. This review highlights the patents on the preparation of non-fluorinated membranes (sulfonated aromatic polymer membranes and porous membranes) as alternatives to high-cost perfluorinated polymers and their VRFB performance. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Materials comprising polydienes and hydrophilic polymers and related methods

DOEpatents

Mays, Jimmy W [Knoxville, TN; Deng, Suxiang [Knoxville, TN; Mauritz, Kenneth A [Hattiesburg, MS; Hassan, Mohammad K [Hattiesburg, MS; Gido, Samuel P [Hadley, MA

2011-11-22

Materials prepared from polydienes, such as poly(cyclohexadiene), and hydrophilic polymers, such as poly(alkylene oxide), are described. Methods of making the materials and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization are also provided. The materials can be crosslinked and sulfonated, and can include copolymers and polymer blends.

Discovery of a metalloenzyme-like cooperative catalytic system of metal nanoclusters and catechol derivatives for the aerobic oxidation of amines.

PubMed

Yuan, Hao; Yoo, Woo-Jin; Miyamura, Hiroyuki; Kobayashi, Shū

2012-08-29

We have discovered a new class of cooperative catalytic system, consisting of heterogeneous polymer-immobilized bimetallic Pt/Ir alloyed nanoclusters (NCs) and 4-tert-butylcatechol, for the aerobic oxidation of amines to imines under ambient conditions. After optimization, the desired imines were obtained in good to excellent yields with broad substrate scope. The reaction rate was determined to be first-order with respect to the substrate and catechol and zero-order for the alloyed Pt/Ir NC catalyst. Control studies revealed that both the heterogeneous NC catalyst and 4-tert-butylcatechol are essential and act cooperatively to facilitate the aerobic oxidation under mild conditions.

The diffusion and conduction of lithium in poly(ethylene oxide)-based sulfonate ionomers

NASA Astrophysics Data System (ADS)

LaFemina, Nikki H.; Chen, Quan; Colby, Ralph H.; Mueller, Karl T.

2016-09-01

Pulsed field gradient nuclear magnetic resonance spectroscopy and dielectric relaxation spectroscopy have been utilized to investigate lithium dynamics within poly(ethylene oxide) (PEO)-based lithium sulfonate ionomers of varying ion content. The ion content is set by the fraction of sulfonated phthalates and the molecular weight of the PEO spacer, both of which can be varied independently. The molecular level dynamics of the ionomers are dominated by either Vogel-Fulcher-Tammann or Arrhenius behavior depending on ion content, spacer length, temperature, and degree of ionic aggregation. In these ionomers the main determinants of the self-diffusion of lithium and the observed conductivities are the ion content and ionic states of the lithium ion, which are profoundly affected by the interactions of the lithium ions with the ether oxygens of the polymer. Since many lithium ions move by segmental polymer motion in the ion pair state, their diffusion is significantly larger than that estimated from conductivity using the Nernst-Einstein equation.

Formation of Light Absorbing Soluble Secondary Organics and Insoluble Polymeric Particles from the Dark Reaction of Catechol and Guaiacol with Fe(III).

PubMed

Slikboer, Samantha; Grandy, Lindsay; Blair, Sandra L; Nizkorodov, Sergey A; Smith, Richard W; Al-Abadleh, Hind A

2015-07-07

Transition metals such as iron are reactive components of environmentally relevant surfaces. Here, dark reaction of Fe(III) with catechol and guaiacol was investigated in an aqueous solution at pH 3 under experimental conditions that mimic reactions in the adsorbed phase of water. Using UV-vis spectroscopy, liquid chromatography, mass spectrometry, elemental analysis, dynamic light scattering, and electron microscopy techniques, we characterized the reactants, intermediates, and products as a function of reaction time. The reactions of Fe(III) with catechol and guaiacol produced significant changes in the optical spectra of the solutions due to the formation of light absorbing secondary organics and colloidal organic particles. The primary steps in the reaction mechanism were shown to include oxidation of catechol and guaiacol to hydroxy- and methoxy-quinones. The particles formed within a few minutes of reaction and grew to micron-size aggregates after half an hour reaction. The mass-normalized absorption coefficients of the particles were comparable to those of strongly absorbing brown carbon compounds produced by biomass burning. These results could account for new pathways that lead to atmospheric secondary organic aerosol formation and abiotic polymer formation on environmental surfaces mediated by transition metals.

Ion Exchange Polymeric Coatings for Selective Capacitive Deionization

NASA Astrophysics Data System (ADS)

Jain, Amit; Kim, Jun; Li, Qilin; Verduzco, Rafael

Capacitive deionization (CDI) is an energy-efficient technology for adsorbing and removing scalants and foulants from water by utilizing electric potential between porous carbon electrodes. Currently, industrial application of CDI is limited to low salinity waters due to the limited absorption capacities of carbon electrodes. However, CDI can potentially be used as a low-cost approach to selectively remove divalent ions from high salinity water. Divalent ions such as sulfonates and carbonates cause scaling and thus performance deterioration of membrane-based desalination systems. In this work, we investigated ion-exchange polymer coatings for use in a membrane capacitive deionization (MCDI) process for selective removal of divalent ions. Poly-Vinyl Alcohol (PVA) base polymer was crosslinked and charged using sulfo-succinic acid (SSA) to give a cation exchange layer. 50 um thick standalone polymer films had a permeability of 4.25*10-7 cm2/s for 10mM NaCl feed. Experiments on electrodes with as low as 10 υm thick coating of cation exchange polymer are under progress and will be evaluated on the basis of their selective salt removal efficiency and charge efficiency, and in future we will extend this work to sulfonated block copolymers and anion exchange polymers.

Effect of Redox “Non-Innocent” Linker on the Catalytic Activity of Copper-Catecholate-Decorated Metal–Organic Frameworks

DOE PAGES

Zhang, Xuan; Vermeulen, Nicolaas A.; Huang, Zhiyuan; ...

2017-12-26

Two new UiO-68 type of Zr-MOFs featuring redox non-innocent catechol-based linkers of different redox activities have been synthesized through a de novo mixed-linker strategy. Also, metalation of the MOFs with Cu(II) precursors triggers the reduction of Cu(II) by the phenyl-catechol groups to Cu(I) with the concomitant formation of semiquinone radicals as evidenced by EPR and XPS characterization. The MOF-supported catalysts are selective toward the allylic oxidation of cyclohexene and it is found that the presence of in situ-generated Cu(I) species exhibits enhanced catalytic activity as compared to a similar MOF with Cu(II) metalated naphthalenyl-dihydroxy groups. Here, this work unveils themore » importance of metal-support redox interactions in the catalytic activity of MOF-supported catalysts which are not easily accessible in traditional metal oxide supports.« less

Effect of Redox “Non-Innocent” Linker on the Catalytic Activity of Copper-Catecholate-Decorated Metal–Organic Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuan; Vermeulen, Nicolaas A.; Huang, Zhiyuan

Two new UiO-68 type of Zr-MOFs featuring redox non-innocent catechol-based linkers of different redox activities have been synthesized through a de novo mixed-linker strategy. Also, metalation of the MOFs with Cu(II) precursors triggers the reduction of Cu(II) by the phenyl-catechol groups to Cu(I) with the concomitant formation of semiquinone radicals as evidenced by EPR and XPS characterization. The MOF-supported catalysts are selective toward the allylic oxidation of cyclohexene and it is found that the presence of in situ-generated Cu(I) species exhibits enhanced catalytic activity as compared to a similar MOF with Cu(II) metalated naphthalenyl-dihydroxy groups. Here, this work unveils themore » importance of metal-support redox interactions in the catalytic activity of MOF-supported catalysts which are not easily accessible in traditional metal oxide supports.« less

Magnetic particles

NASA Technical Reports Server (NTRS)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor); Rembaum, Alan (Inventor); Richards, Gil F. (Inventor)

1987-01-01

Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method.

Mussel-Inspired Adhesives and Coatings

PubMed Central

Lee, Bruce P.; Messersmith, P.B.; Israelachvili, J.N.; Waite, J.H.

2011-01-01

Mussels attach to solid surfaces in the sea. Their adhesion must be rapid, strong, and tough, or else they will be dislodged and dashed to pieces by the next incoming wave. Given the dearth of synthetic adhesives for wet polar surfaces, much effort has been directed to characterizing and mimicking essential features of the adhesive chemistry practiced by mussels. Studies of these organisms have uncovered important adaptive strategies that help to circumvent the high dielectric and solvation properties of water that typically frustrate adhesion. In a chemical vein, the adhesive proteins of mussels are heavily decorated with Dopa, a catecholic functionality. Various synthetic polymers have been functionalized with catechols to provide diverse adhesive, sealant, coating, and anchoring properties, particularly for critical biomedical applications. PMID:22058660

Organic Inorganic Hybrid Solar Cell Efficiency Improvement By Employing Au Nanocluster

DTIC Science & Technology

2015-06-14

ABSTRACT 16. SECURITY CLASSIFICATION OF: Poly( 3,4-ethyllenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS), a P-type organic polymer is frequently...Addition of small volume percentage of organic additives such as dimethyl sulfoxide (DMSO) has a positive effect on the conductivity of this polymer . In...Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 hybrid solar cell, tunable conductivity, organic polymer , heterojunction, nanocluster

Effect of water on the changes in morphology and proton conductivity for the highly crystalline hydrocarbon polymer electrolyte membrane for fuel cells.

PubMed

Barique, Mohammad A; Wu, Libin; Takimoto, Naohiko; Kidena, Koh; Ohira, Akihiro

2009-12-10

The effects of water on the changes in morphology of sulfonated poly(phenylene sulfide) (SPPS) hydrocarbon polymer electrolyte membranes (PEM) with an ion exchange capacity (IEC) of 0-2.0 mequiv/g are investigated using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). Wide-angle X-ray scattering (WAXS) was used to characterize the effect of direct sulfonation on the changes in membrane crystalline structure, and it was found that the crystallinity and crystallite domain size decrease and the volume of the amorphous region in the SPPS membranes increases with increasing IEC. The experimental data have been fitted to the Porod law for approaching the analysis of the sharpness of the polymer/water interface, development of the proton channel, or dispersion of water in the hydrated membranes. Porod plots showed positive deviation which revealed that the polymer/water interface in the hydrated SPPS membrane is not smooth but diffused and a well-developed proton channel does not form in the membrane.

Design, fabrication and evaluation of intelligent sulfone-selective polybenzimidazole nanofibers.

PubMed

Ogunlaja, Adeniyi S; du Sautoy, Carol; Torto, Nelson; Tshentu, Zenixole R

2014-08-01

Molecularly imprinted polybenzimidazole nanofibers fabricated for the adsorption of oxidized organosulfur compounds are presented. The imprinted polymers exhibited better selectivity for their target model sulfone-containing compounds with adsorption capacities of 28.5±0.4mg g(-1), 29.8±2.2mg g(-1) and 20.1±1.4mg g(-1) observed for benzothiophene sulfone (BTO2), dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) respectively. Molecular modeling based upon the density functional theory (DFT) indicated that hydrogen bond interactions may take place between sulfone oxygen groups with NH groups of the PBI. Further DFT also confirmed the feasibility of π-π interactions between the benzimidazole rings and the aromatic sulfone compounds. The adsorption mode followed the Freundlich (multi-layered) adsorption isotherm which indicated possible sulfone-sulfone interactions. A home-made pressurized hot water extraction (PHWE) system was employed for the extraction/desorption of sulfone compounds within imprinted nanofibers at 1mL min(-1), 150°C and 30 bar. PHWE used a green solvent (water) and achieved better extraction yields compared to the Soxhlet extraction process. The application of molecularly imprinted polybenzimidazole (PBI) nanofibers displayed excellent sulfur removal, with sulfur in fuel after adsorption falling below the determined limit of detection (LOD), which is 2.4mg L(-1)S, and with a sulfur adsorption capacity of 5.3±0.4mg g(-1) observed for application in the fuel matrix. Copyright © 2014 Elsevier B.V. All rights reserved.

Clustering Effects on Dynamics in Ionomer Solutions: A Neutron Spin Echo Insight

NASA Astrophysics Data System (ADS)

Perahia, Dvora; Wijesinghe, Sidath; Senanayake, Manjula; Wickramasinghe, Anuradhi; Mohottalalage, Supun S.; Ohl, Michael

Ionizable blocks in ionomers associate into aggregates serving as physical cross-links and concurrently form transport pathways. The dynamics of ionomers underline their functionality. Incorporating small numbers of ionic groups into polymers significantly constraint their dynamics. Recent computational studies demonstrated a direct correlation between ionic cluster morphology and polymer dynamics. Here using neutron spin echo, we probe the segmental dynamics of polystyrene sulfonate (PSS) as the degree of sulfonation of the PSS and the solution dielectrics are varied. Specifically, 20Wt% PSS of 11,000 g/mol with polydispersity of 1.02 with 3% and 9% sulfonation were studies in toluene (dielectric constant ɛ = 2.8), a good solvent for polystyrene, and with 5Wt% of ethanol (ɛ = 24.3l) added. The dynamic structure factor S(q,t) was analyzed with a single exponential except for a limited q range where two time constants associated with constraint and mobile segments were detected. S(q,t) exhibits several distinctive time and length scales for the dynamics with a crossover appearing at the length scale of the ionic clusters. NSF DMR 1611136.

Role of sulfonation in the stability, reactivity, and selectivity of poly(ether imide) used to develop ion exchange membranes: DFT study with application to fuel cells.

PubMed

López-Chávez, Ernesto; Peña-Castañeda, Yésica A; de la Portilla-Maldonado, L César; Guzmán-Pantoja, Javier; Martínez-Magadán, José Manuel; Oviedo-Roa, Raúl; de Landa Castillo-Alvarado, Fray; Cruz-Torres, Armando

2014-07-01

The design of polymer electrolyte membranes for fuel cells must satisfy two equally important fundamental principles: optimization of the reactivity and the selectivity in order to improve the ion transport properties of the membrane as well as its long-term stability in the hydrated state at high temperature (above 100 °C). A study utilizing density functional theory (DFT) to elucidate the effect of the degree of sulfonation on the chemical stability, reactivity, and selectivity of poly(ether imide) (PEI), which allows the ionic transport properties of the membrane to be predicted, is reported here. Sulfonated poly(ether imide) (SPEI) structures with (-SO3H) n (n = 1-6) groups were built and optimized in order to calculate the above properties as functions of the number of sulfonyl groups. A comparative study demonstrated that the SPEI with four sulfonyl groups in its backbone is the polymer with the properties best suited for use in fuel cells.

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

PubMed

Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

2013-01-01

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

Anion exchange membranes based on terminally crosslinked methyl morpholinium-functionalized poly(arylene ether sulfone)s

NASA Astrophysics Data System (ADS)

Kwon, Sohyun; Rao, Anil H. N.; Kim, Tae-Hyun

2018-01-01

Azide-assisted terminal crosslinking of methyl morpholinium-functionalized poly(arylene ether sulfone) block copolymers yields products (xMM-PESs) suitable for use as anion exchange membranes. By combining the advantages of bulky morpholinium conductors and our unique polymer network crosslinked only at the termini of the polymer chains, we can produce AEMs that after the crosslinking show minimal loss in conductivity, yet with dramatically reduced water uptake. Terminal crosslinking also significantly increases the thermal, mechanical and chemical stability levels of the membranes. A high ion conductivity of 73.4 mS cm-1 and low water uptake of 26.1% at 80 °C are obtained for the crosslinked membrane with higher amount of hydrophilic composition, denoted as xMM-PES-1.5-1. In addition, the conductivity of the crosslinked xMM-PES-1.5-1 membrane exceeds that of its non-crosslinked counterpart (denoted as MM-PES-1.5-1) above 60 °C at 95% relative humidity because of its enhanced water retention capacity caused by the terminally-crosslinked structure.

Antibacterial surface modified of novel nanocomposite sulfonated polyethersulfone/polyrhodanine membrane

NASA Astrophysics Data System (ADS)

Rostam, Abbas Babaei; Peyravi, Majid; Ghorbani, Mohsen; Jahanshahi, Mohsen

2018-01-01

In this study, sulfonated-polyethersulfone/polyrhodanine (SPES/PRh) membranes with antibacterial behavior were fabricated. Polyethersulfone (PES) sulfonation was performed to enhance its hydrophilicity and next polyrhodanine nanoparticles (PRhNPs) were synthesized along with the sulfonated PES (SPES) by polyrhodanine (PRh) in situ polymerization. The sulfonation step also helps making composite membrane due to development of probable bondings and polymers engagements. The constructed membranes characterization was performed by FTIR, FESEM, contact angle, 1H NMR, TGA and EDS analyses. SPES/PRh membrane had enhanced hydrophilicity and consequently better fluxes for aqueous solutions. The composite SPES/PRh membrane flux was improved to 139/78 L/m2 h comparing 58.21 L/m2 h for SPES one. Membrane operational performances, antibacterial and antibiofouling tests showed improved flux, better rejection and appropriate antibacterial and antibiofouling properties for SPES/PRh membrane. The 100% bacteria mortality for specified concentrations and appropriate inhibition zones up to 9 mm have been achieved. It is generally a suitable membrane to provide proper performance beside antibacterial and antibiofouling behavior.

Polydopamine-like Coatings as Payload Gatekeepers for Mesoporous Silica Nanoparticles.

PubMed

Moreno-Villaécija, Miguel-Ángel; Sedó-Vegara, Josep; Guisasola, Eduardo; Baeza, Alejandro; Regí, María Vallet; Nador, Fabiana; Ruiz-Molina, Daniel

2018-03-07

We report the use of bis-catecholic polymers as candidates for obtaining effective, tunable gatekeeping coatings for mesoporous silica nanoparticles (MSNs) intended for drug release applications. In monomers, catechol rings act as adhesive moieties and reactive sites for polymerization, together with middle linkers which may be chosen to tune the physicochemical properties of the resulting coating. Stable and low-toxicity coatings (pNDGA and pBHZ) were prepared from two bis-catechols of different polarity (NDGA and BHZ) on MSN carriers previously loaded with rhodamine B (RhB) as a model payload, by means of a previously reported synthetic methodology and without any previous surface modification. Coating robustness and payload content were shown to depend significantly on the workup protocol. The release profiles in a model physiological PBS buffer of coated systems (RhB@MSN@pNDGA and RhB@MSN@pBHZ) showed marked differences in the "gatekeeping" behavior of each coating, which correlated qualitatively with the chemical nature of their respective linker moieties. While the uncoated system (RhB@MSN) lost its payload almost completely after 2 days, release from RhB@MSN@pNDGA was virtually negligible, likely due to the low polarity of the parent bis-catechol (NDGA). As opposed to these extremes, RhB@MSN@pBHZ presented the most promising behavior, showing an intermediate release of 50% of the payload in the same period of time.

Influence of para-substituents on the oxidative metabolism of o-nitrophenols by Pseudomonas putida B2.

PubMed Central

Zeyer, J; Kocher, H P; Timmis, K N

1986-01-01

Pseudomonas putida B2 is able to grow on o-nitrophenol (ONP) as the sole source of carbon and nitrogen. ONP was converted by a nitrophenol oxygenase to nitrite and catechol. Catechol was then attacked by a catechol 1,2-dioxygenase and further degraded through an ortho-cleavage pathway. ONP derivatives which were para-substituted with a methyl-, chloro-, carboxy-, formyl- or nitro-group failed to support growth of strain B2. Relevant catabolic enzymes were characterized to analyze why these derivatives were not mineralized. Nitrophenol oxygenase of strain B2 is a soluble, NADPH-dependent enzyme that is stimulated by magnesium, manganese, and calcium ions. It is active toward ONP, 4-methyl-, 4-chloro-, and to a lesser extent, 4-formyl-ONP but not toward 4-carboxy- or 4-nitro-ONP. In addition, 4-formyl-, 4-carboxy-, and 4-nitro-ONP failed to induce the formation of nitrophenol oxygenase. Catechol 1,2-dioxygenase of strain B2 is active toward catechol and 4-methyl-catechol but only poorly active toward chlorinated catechols. 4-Methyl-catechol is likely to be degraded to methyl-lactones, which are often dead-end metabolites in bacteria. Thus, of the compounds tested, only unsubstituted ONP acts as an inducer and substrate for all of the enzymes of a productive catabolic pathway. PMID:3752997

Solid polymer electrolytes

DOEpatents

Abraham, Kuzhikalail M.; Alamgir, Mohamed; Choe, Hyoun S.

1995-01-01

This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.

Phase Behavior of a Single Structured Ionomer Chain in Solution

DOE PAGES

Aryal, Dipak; Etampawala, Thusitha; Perahia, Dvora; ...

2014-08-14

Structured polymers offer a means to tailor transport pathways within mechanically stable manifolds. Here we examine the building block of such a membrane, namely a single large pentablock co-polymer that consist of a center block of a randomly sulfonated polystyrene, designed for transport, tethered to poly-ethylene-r-propylene and end-capped by poly-t-butyl styrene, for mechanical stability,using molecular dynamics simulations. The polymer structure in a cyclohexane-heptane mixture, a technologically viable solvent, and in water, a poor solvent for all segments and a ubiquitous substance is extracted. In all solvents the pentablock collapsed into nearly spherical aggregates where the ionic block is segregated. Inmore » hydrophobic solvents, the ionic block resides in the center, surrounded by swollen intermix of flexible and end blocks. In water all blocks are collapsed with the sulfonated block residing on the surface. Our results demonstrate that solvents drive different local nano-segregation, providing a gateway to assemble membranes with controlled topology.« less

Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s

PubMed Central

Yuen, Alexander; Wojtecki, Rudy J.; Hedrick, James L.; García, Jeannette M.

2016-01-01

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers. PMID:27354514

Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s.

PubMed

Jones, Gavin O; Yuen, Alexander; Wojtecki, Rudy J; Hedrick, James L; García, Jeannette M

2016-07-12

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers.

A highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film with the solvent bath treatment by dimethyl sulfoxide as cathode for polymer tantalum capacitor

NASA Astrophysics Data System (ADS)

Ma, Xiaopin; Wang, Xiuyu; Li, Mingxiu; Chen, Tongning; Zhang, Hao; Chen, Qiang; Ding, Bonan; Liu, Yanpeng

2016-06-01

The highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films were prepared on porous tantalum pentoxide surface as cathode for polymer tantalum capacitors (PTC). The electrical performances of PTC with PEDOT:PSS films as cathode were optimized by dimethyl sulfoxide (DMSO) bath treatment. With the DMSO-bath treatment of PTC, the equivalent series resistance (ESR) of PTC decreased from 25 mΩ to 9 mΩ. The ultralow ESR led to better capacitance-frequency performance. The device reliability investigation revealed the enhanced environmental stability of PTC. The enhanced performances were attributed to the conductivity improvement of PEDOT:PSS cathode films and the removal of excess PSS from PEDOT:PSS films.

Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al{sub 2}O{sub 3}) polyblends as electrolyte membranes for fuel cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonggo, Siang Tandi, E-mail: standigonggo@yahoo.com

2015-09-30

The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al{sub 2}O{sub 3}) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al{sub 2}O{sub 3} membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al{sub 2}O{sub 3} ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al{sub 2}O{sub 3} blend showed higher proton conductivity than Nafion 117.

Sulfonated chitosan and dopamine based coatings for metallic implants in contact with blood.

PubMed

Campelo, Clayton S; Chevallier, Pascale; Vaz, Juliana M; Vieira, Rodrigo S; Mantovani, Diego

2017-03-01

Thrombosis and calcification constitute the main clinical problems when blood-interacting devices are implanted in the body. Coatings with thin polymer layers represent an acknowledged strategy to modulate interactions between the material surface and the blood environment. To ensure the implant success, at short-term the coating should limit platelets adhesion and delay the clot formation, and at long-term it should delay the calcification process. Sulfonated chitosan, if compared to native chitosan, shows the unique ability to reduce proteins adsorption, decrease thrombogenic properties and limit calcification. In this work, stainless steel surfaces, commonly used for cardiovascular applications, were coated with sulfonated chitosan, by using dopamine and PEG as anchors, and the effect of these grafted surfaces on platelet adhesion, clot formation as well as on calcification were investigated. Surface characterization techniques evidenced that the coating formation was successful, and the sulfonated chitosan grafted sample exhibited a higher roughness and hydrophilicity, if compared to native chitosan one. Moreover, sulfonated surface limited platelet activation and the process of clot formation, thus confirming its high biological performances in blood. Calcium deposits were also lower on the sulfonated chitosan sample compared to the chitosan one, thus showing that calcification was minimal in presence of sulfonate groups. In conclusion, this sulfonated-modified surface has potential to be as blood-interacting material. Copyright © 2016. Published by Elsevier B.V.

Structure-property relationships in polymers for dielectric capacitors

NASA Astrophysics Data System (ADS)

Gupta, Sahil

Effective energy storage is a key challenge of the 21st century that has fueled research in the area of energy storage devices. In this dissertation, structure-property relationships have been evaluated for polymers that might be suitable for storing energy in high-energy density, high-temperature capacitors. Firstly, hydroxyl-modified polypropylenes (PPOH) were synthesized by copolymerization of the propylene and undecenyloxytrimethylsilane monomers. The presence of H-bonding in PPOH copolymers increased their glass-transition temperature. Steric hindrance by the comonomer reduced the PP crystal growth rate and crystal size, resulting in a melting point depression. The comonomer was restricted outside the crystalline domains leaving the alpha-monoclinic crystal structure of PP unaffected, but increasing the fold-surface free energy. Crystallization was slower for PPOH copolymers than PP, but exhibited a skewed bell curve as a function of hydroxyl concentration. H-bonding persisted even at melt temperatures up to 250°C resulting in a higher elasticity and viscosity for PPOH copolymers. Secondly, sulfonated poly(ether ether ketone) (HSPEEK) was synthesized by sulfonating PEEK with sulfuric acid, and further neutralized with Zn to obtain ZnSPEEK. The thermal and dielectric properties of SPEEK were compared with PEEK. The glass-transition increased and melting point were high enough to enable the use of polymer at 180°C. The incorporation of sulfonic groups in PEEK increased the dielectric constant. HSPEEK had a higher dielectric constant than ZnSPEEK due to higher dipolar mobility, but the dielectric loss was also higher for HSPEEK due to electrode polarization and DC conduction. These results were consistent with our observations from sulfonated polystyrene (HSPS), which was used as a >model&lang' polymer. Lastly, commercial poly(4-methyl-1-pentene) (P4MP) was characterized to check its viability as a high-temperature polymer dielectric. Thermal stability up to 200°C, high melting point (> 225°C) and melting onset at 160 - 190°C indicated that P4MP could be used at 180 - 200°C. Thin free-standing films (~10 mum) with controlled crystal structure and surface morphology were prepared using blade coating and their drying dynamics were measured using a custom-designed solvent-casting platform. These films were further stretched uniaxially or biaxially, and their effect on the dielectric properties of P4MP was studied.

A new avenue to the synthesis of GAG-mimicking polymers highly promoting neural differentiation of embryonic stem cells.

PubMed

Wang, Mengmeng; Lyu, Zhonglin; Chen, Gaojian; Wang, Hongwei; Yuan, Yuqi; Ding, Kaiguo; Yu, Qian; Yuan, Lin; Chen, Hong

2015-10-28

A new strategy for the fabrication of glycosaminoglycan (GAG) analogs was proposed by copolymerizing the sulfonated unit and the glyco unit, 'splitted' from the sulfated saccharide building blocks of GAGs. The synthetic polymers can promote cell proliferation and neural differentiation of embryonic stem cells with the effects even better than those of heparin.

Solid polymer electrolytes

DOEpatents

Abraham, K.M.; Alamgir, M.; Choe, H.S.

1995-12-12

This invention relates to Li ion (Li{sup +}) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF{sub 3}SO{sub 2}){sub 2}, LiAsF{sub 6}, and LiClO{sub 4}. 2 figs.

Enhanced Proton Conductivity and Methanol Permeability Reduction via Sodium Alginate Electrolyte-Sulfonated Graphene Oxide Bio-membrane

NASA Astrophysics Data System (ADS)

Shaari, N.; Kamarudin, S. K.; Basri, S.; Shyuan, L. K.; Masdar, M. S.; Nordin, D.

2018-03-01

The high methanol crossover and high cost of Nafion® membrane are the major challenges for direct methanol fuel cell application. With the aim of solving these problems, a non-Nafion polymer electrolyte membrane with low methanol permeability and high proton conductivity based on the sodium alginate (SA) polymer as the matrix and sulfonated graphene oxide (SGO) as an inorganic filler (0.02-0.2 wt%) was prepared by a simple solution casting technique. The strong electrostatic attraction between -SO3H of SGO and the sodium alginate polymer increased the mechanical stability, optimized the water absorption and thus inhibited the methanol crossover in the membrane. The optimum properties and performances were presented by the SA/SGO membrane with a loading of 0.2 wt% SGO, which gave a proton conductivity of 13.2 × 10-3 Scm-1, and the methanol permeability was 1.535 × 10-7 cm2 s-1 at 25 °C, far below that of Nafion (25.1 × 10-7 cm2 s-1) at 25 °C. The mechanical properties of the sodium alginate polymer in terms of tensile strength and elongation at break were improved by the addition of SGO.

POSS-Containing Bioinspired Adhesives with Enhanced Mechanical and Optical Properties for Biomedical Applications.

PubMed

Pramudya, Irawan; Rico, Catalina G; Lee, Choogon; Chung, Hoyong

2016-12-12

A new terpolymer adhesive, poly(2-methoxyethyl acrylate-co-N-methacryloyl 3,4-dihydroxyl-l-phenylalanine-co-heptaisobutyl substituted polyhedral oligomeric silsesquioxane propyl methacrylate) (poly(MEA-co-MDOPA-co-MPOSS) was synthesized by thermally initiated radical polymerization. In this study, we investigated the effect of the POSS component on adhesion, mechanical, and optical properties of the catechol-group containing bioinspired adhesives. The terpolymer contains the catechol group which is known to improve the adhesion properties of polymers. Only a very small amount of the POSS-containing monomer, MPOSS, was included, 0.5 mol %. In the presence of POSS, the synthesized poly(MEA-co-MDOPA-co-MPOSS) demonstrated strong adhesion properties, 23.2 ± 6.2 J/m 2 with 0.05 N preloading and 300 s holding time, compared to many previously prepared catechol-containing adhesives. The mechanical properties (Young's modulus and stress at 10% strain) of the POSS-containing terpolymer showed significant increases (6-fold higher) over the control polymer, which does not contain POSS. Optical transmittance of the synthesized terpolymer was also improved significantly in the visible light range, 450-750 nm. Cell testing with human embryonic kidney cells (HEK293A) indicates that the new terpolymer is a promising candidate in biomedical adhesives without acute cytotoxicity. The synthesized poly(MEA-co-MDOPA-co-MPOSS) is the first example of POSS-containing pressure sensitive bioinspired adhesive for biomedical applications. The study of poly(MEA-co-MDOPA-co-MPOSS) demonstrated a convenient method to enhance two important properties, mechanical and optical properties, by the addition of a very small amount of POSS. Based on this study, it was found that POSS can be used to strengthen mechanical properties of bioinspired adhesive without the need for a covalent cross-linking step.

Gold nanoparticle-polymer nanocomposites synthesized by room temperature atmospheric pressure plasma and their potential for fuel cell electrocatalytic application

PubMed Central

Zhang, Ri-Chao; Sun, Dan; Zhang, Ruirui; Lin, Wen-Feng; Macias-Montero, Manuel; Patel, Jenish; Askari, Sadegh; McDonald, Calum; Mariotti, Davide; Maguire, Paul

2017-01-01

Conductive polymers have been increasingly used as fuel cell catalyst support due to their electrical conductivity, large surface areas and stability. The incorporation of metal nanoparticles into a polymer matrix can effectively increase the specific surface area of these materials and hence improve the catalytic efficiency. In this work, a nanoparticle loaded conductive polymer nanocomposite was obtained by a one-step synthesis approach based on room temperature direct current plasma-liquid interaction. Gold nanoparticles were directly synthesized from HAuCl4 precursor in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The resulting AuNPs/PEDOT:PSS nanocomposites were subsequently characterized under a practical alkaline direct ethanol fuel cell operation condition for its potential application as an electrocatalyst. Results show that AuNPs sizes within the PEDOT:PSS matrix are dependent on the plasma treatment time and precursor concentration, which in turn affect the nanocomposites electrical conductivity and their catalytic performance. Under certain synthesis conditions, unique nanoscale AuNPs/PEDOT:PSS core-shell structures could also be produced, indicating the interaction at the AuNPs/polymer interface. The enhanced catalytic activity shown by AuNPs/PEDOT:PSS has been attributed to the effective electron transfer and reactive species diffusion through the porous polymer network, as well as the synergistic interfacial interaction at the metal/polymer and metal/metal interfaces. PMID:28436454

Gold nanoparticle-polymer nanocomposites synthesized by room temperature atmospheric pressure plasma and their potential for fuel cell electrocatalytic application

NASA Astrophysics Data System (ADS)

Zhang, Ri-Chao; Sun, Dan; Zhang, Ruirui; Lin, Wen-Feng; Macias-Montero, Manuel; Patel, Jenish; Askari, Sadegh; McDonald, Calum; Mariotti, Davide; Maguire, Paul

2017-04-01

Conductive polymers have been increasingly used as fuel cell catalyst support due to their electrical conductivity, large surface areas and stability. The incorporation of metal nanoparticles into a polymer matrix can effectively increase the specific surface area of these materials and hence improve the catalytic efficiency. In this work, a nanoparticle loaded conductive polymer nanocomposite was obtained by a one-step synthesis approach based on room temperature direct current plasma-liquid interaction. Gold nanoparticles were directly synthesized from HAuCl4 precursor in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The resulting AuNPs/PEDOT:PSS nanocomposites were subsequently characterized under a practical alkaline direct ethanol fuel cell operation condition for its potential application as an electrocatalyst. Results show that AuNPs sizes within the PEDOT:PSS matrix are dependent on the plasma treatment time and precursor concentration, which in turn affect the nanocomposites electrical conductivity and their catalytic performance. Under certain synthesis conditions, unique nanoscale AuNPs/PEDOT:PSS core-shell structures could also be produced, indicating the interaction at the AuNPs/polymer interface. The enhanced catalytic activity shown by AuNPs/PEDOT:PSS has been attributed to the effective electron transfer and reactive species diffusion through the porous polymer network, as well as the synergistic interfacial interaction at the metal/polymer and metal/metal interfaces.

21 CFR 177.2500 - Polyphenylene sulfone resins.

Code of Federal Regulations, 2010 CFR

2010-04-01

... consist of basic resin produced by reacting polyphenylene sulfide with peracetic acid such that the... sanction or approval. (c) Specifications. The glass transition temperature of the polymer is 360±5 °C as...

21 CFR 177.2500 - Polyphenylene sulfone resins.

Code of Federal Regulations, 2011 CFR

2011-04-01

... consist of basic resin produced by reacting polyphenylene sulfide with peracetic acid such that the... sanction or approval. (c) Specifications. The glass transition temperature of the polymer is 360±5 °C as...

Interaction between amphiphilic ionic liquid 1-butyl-3-methylimidazolium octyl sulfate and anionic polymer of sodium polystyrene sulfonate in aqueous medium

NASA Astrophysics Data System (ADS)

Barhoumi, Z.; Saini, M.; Amdouni, N.; Pal, A.

2016-09-01

The micellization of an aqueous solution of the surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium octylsufate (C4mim)(C8OSO3) and its interaction with an anionic polymer sodium polystyrene sulfonate, (NaPSS) were studied using conductimetry, tensiometry and fluorimetry. Surface tension profile shows a more dramatic increase in the value of surface tension of aqueous (C4mim)(C8OSO3) before the critical micelle concentration (cmc) of IL. The critical micelle concentration (cmc) value of this surfactant was found out from conductance measurements. The thermodynamic parameters, i.e., Gibb's free energy, enthalpy, and entropy of micellization of the IL in aqueous solution have been calculated. Behavior of fluorescence probe confirms the binding interactions between SAIL and the polyelectrolyte.

A highly aromatic and sulfonated ionomer for high elastic modulus ionic polymer membrane micro-actuators

NASA Astrophysics Data System (ADS)

Hatipoglu, Gokhan; Liu, Yang; Zhao, Ran; Yoonessi, Mitra; Tigelaar, Dean M.; Tadigadapa, Srinivas; Zhang, Q. M.

2012-05-01

A high modulus, sulfonated ionomer synthesized from 4,6-bis(4-hydroxyphenyl)-N,N-diphenyl-1,3,5-triazin-2-amine and 4,4‧-biphenol with bis(4-fluorophenyl)sulfone (DPA-PS:BP) is investigated for ionic polymer actuators. The uniqueness of DPA-PS:BP is that it can have a high ionic liquid (IL) uptake and consequently generates a high intrinsic strain response, which is >1.1% under 1.6 V while maintaining a high elastic modulus (i.e. 600 MPa for 65 vol% IL uptake). Moreover, such a high modulus of the active ionomer, originating from the highly aromatic backbone and side-chain-free structure, allows for the fabrication of free-standing thin film micro-actuators (down to 5 µm thickness) via the solution cast method and focused-ion-beam milling, which exhibits a much higher bending actuation, i.e. 43 µm tip displacement and 180 kPa blocking stress for a 200 µm long and 5 µm thick cantilever actuator, compared with the ionic actuators based on traditional ionomers such as Nafion, which has a much lower elastic modulus (50 MPa) and actuation strain.

Activation of Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol) using a Supramolecular Trigger.

PubMed

Phillips, Daniel J; Congdon, Thomas R; Gibson, Matthew I

2016-03-07

Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity - a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization. Upon addition of Fe 3+ , larger supramolecular star polymers form by assembly with two or three catechols. This increase in molecular weight effectively 'switches on' the IRI activity and is the first example of external control over the function of AFP mimetics. This provides a simple but elegant solution to the challenge of external control of AFP-mimetic function.

Soft nanoparticles: nano ionic networks of associated ionic polymers

DOE PAGES

Aryal, Dipak; Grest, Gary S.; Perahia, Dvora

2017-01-01

Directing the formation of nanostructures that serve as building blocks of membranes presents an immense step towards engineering controlled polymeric ion transport systems. Here, using the exquisite atomic detail captured by molecular dynamics simulations, we follow the assembly of a co-polymer that consists of polystyrene sulfonate tethered symmetrically to hydrophobic blocks, realizing a new type of long lived solvent-responsive soft nanoparticle.

THE RELATION OF CHEMICAL STRUCTURE IN CATECHOL COMPOUNDS AND DERIVATIVES TO POISON IVY HYPERSENSITIVENESS IN MAN AS SHOWN BY THE PATCH TEST

PubMed Central

Keil, Harry; Wasserman, David; Dawson, Charles R.

1944-01-01

1. Additional evidence is presented in support of the view which postulates a close chemical and biologic relation between the active ingredients in poison ivy and Japan lac. 2. Biologic evidence, based on the use of the patch test in man, is presented in support of the view that the active ingredient in poison ivy is a catechol derivative with a long, unsaturated side-chain in the 3-position. 3. Of the catechol compounds and derivatives studied, group reactions in patients sensitive to poison ivy leaves or extract were exhibited by the following compounds: 3-pentadecyl catechol (100 per cent of 21 cases), 4-pentadecyl catechol (38 per cent of 21 cases), "urushiol" dimethyl ether (33 per cent of 33 cases), 3-pentadecenyl-1'-veratrole (21 per cent of 14 cases), 3-methyl catechol (14 per cent of 21 cases), and hydrourushiol dimethyl ether (10 per cent of 20 cases). It has been found that 3-geranyl catechol shows a practically constant group reactivity in persons sensitive to poison ivy. 4. The uniformly positive group reaction to 3-pentadecyl catechol is notable since this substance possesses a saturated side-chain, whereas the active ingredient in poison ivy is known to have an unsaturated side-chain. 5. The group reactivity was not restricted to the 3-position, for in some instances 4-pentadecyl catechol also gave group reactions which, however, were less intense and less frequent than those shown by 3-pentadecyl catechol. This indicates that in some cases a long side-chain in the 4 position may be effective in producing group specific reactions. 6. Only an occasional person showed sensitiveness to 3-methyl catechol (short side-chain), and in one instance the group reactivity appeared to be specific for the 3-position. 7. The position of the side-chain in the catechol configuration has some bearing on the degree and incidence of group reactions in persons hypersensitive to poison ivy. 8. Evidence is presented to indicate that the introduction of double bonds in the alkyl side-chain increases the incidence and intensity of group reactions. 9. Methylating the hydroxyl groups in the catechol configuration diminishes strongly the incidence of group reactivity but does not eliminate it entirely in persons hypersensitive to poison ivy. Thus, "urushiol" dimethyl ether (3-pentadecadienyl veratrole) gave group reactions in 33 per cent of 33 persons. 10. Methylating the hydroxyl groups as well as saturating the double bonds in the alkyl side-chain still further diminishes the group reactions but an occasional person hypersensitive to poison ivy may still show positive reaction to such a substance as 3-pentadecyl veratrole (hydrourushiol dimethyl ether). In this respect our results are not in full agreement with those recorded by Toyama who stated that hydrourushiol dimethyl ether is entirely harmless. 11. The significance of the group reactivity displayed by certain veratrole compounds is discussed, and several possible explanations of their behavior are advanced. 12. The group reactions discussed in this paper relate only to various catechol and veratrole compounds. Preliminary studies by us indicate that this sensitiveness extends to other phenolic derivatives. 13. Among the veratrole compounds showing positive reactions, the order of frequency and intensity was: (1) "urushiol" dimethyl ether (average of two double bonds); (2) S-pentadecenyl-1'-veratrole (one double bond); (3) hydrourushiol dimethyl ether (saturated side-chain). It may be noted that 4-pentadecyl veratrole was inactive. PMID:19871415

THE RELATION OF CHEMICAL STRUCTURE IN CATECHOL COMPOUNDS AND DERIVATIVES TO POISON IVY HYPERSENSITIVENESS IN MAN AS SHOWN BY THE PATCH TEST.

PubMed

Keil, H; Wasserman, D; Dawson, C R

1944-10-01

1. Additional evidence is presented in support of the view which postulates a close chemical and biologic relation between the active ingredients in poison ivy and Japan lac. 2. Biologic evidence, based on the use of the patch test in man, is presented in support of the view that the active ingredient in poison ivy is a catechol derivative with a long, unsaturated side-chain in the 3-position. 3. Of the catechol compounds and derivatives studied, group reactions in patients sensitive to poison ivy leaves or extract were exhibited by the following compounds: 3-pentadecyl catechol (100 per cent of 21 cases), 4-pentadecyl catechol (38 per cent of 21 cases), "urushiol" dimethyl ether (33 per cent of 33 cases), 3-pentadecenyl-1'-veratrole (21 per cent of 14 cases), 3-methyl catechol (14 per cent of 21 cases), and hydrourushiol dimethyl ether (10 per cent of 20 cases). It has been found that 3-geranyl catechol shows a practically constant group reactivity in persons sensitive to poison ivy. 4. The uniformly positive group reaction to 3-pentadecyl catechol is notable since this substance possesses a saturated side-chain, whereas the active ingredient in poison ivy is known to have an unsaturated side-chain. 5. The group reactivity was not restricted to the 3-position, for in some instances 4-pentadecyl catechol also gave group reactions which, however, were less intense and less frequent than those shown by 3-pentadecyl catechol. This indicates that in some cases a long side-chain in the 4 position may be effective in producing group specific reactions. 6. Only an occasional person showed sensitiveness to 3-methyl catechol (short side-chain), and in one instance the group reactivity appeared to be specific for the 3-position. 7. The position of the side-chain in the catechol configuration has some bearing on the degree and incidence of group reactions in persons hypersensitive to poison ivy. 8. Evidence is presented to indicate that the introduction of double bonds in the alkyl side-chain increases the incidence and intensity of group reactions. 9. Methylating the hydroxyl groups in the catechol configuration diminishes strongly the incidence of group reactivity but does not eliminate it entirely in persons hypersensitive to poison ivy. Thus, "urushiol" dimethyl ether (3-pentadecadienyl veratrole) gave group reactions in 33 per cent of 33 persons. 10. Methylating the hydroxyl groups as well as saturating the double bonds in the alkyl side-chain still further diminishes the group reactions but an occasional person hypersensitive to poison ivy may still show positive reaction to such a substance as 3-pentadecyl veratrole (hydrourushiol dimethyl ether). In this respect our results are not in full agreement with those recorded by Toyama who stated that hydrourushiol dimethyl ether is entirely harmless. 11. The significance of the group reactivity displayed by certain veratrole compounds is discussed, and several possible explanations of their behavior are advanced. 12. The group reactions discussed in this paper relate only to various catechol and veratrole compounds. Preliminary studies by us indicate that this sensitiveness extends to other phenolic derivatives. 13. Among the veratrole compounds showing positive reactions, the order of frequency and intensity was: (1) "urushiol" dimethyl ether (average of two double bonds); (2) S-pentadecenyl-1'-veratrole (one double bond); (3) hydrourushiol dimethyl ether (saturated side-chain). It may be noted that 4-pentadecyl veratrole was inactive.

Fibrillar films obtained from sodium soap fibers and polyelectrolyte multilayers.

PubMed

Zawko, Scott A; Schmidt, Christine E

2011-08-01

An objective of tissue engineering is to create synthetic polymer scaffolds with a fibrillar microstructure similar to the extracellular matrix. Here, we present a novel method for creating polymer fibers using the layer-by-layer method and sacrificial templates composed of sodium soap fibers. Soap fibers were prepared from neutralized fatty acids using a sodium chloride crystal dissolution method. Polyelectrolyte multilayers (PEMs) of polystyrene sulfonate and polyallylamine hydrochloride were deposited onto the soap fibers, crosslinked with glutaraldehyde, and then the soap fibers were leached with warm water and ethanol. The morphology of the resulting PEM structures was a dense network of fibers surrounded by a nonfibrillar matrix. Microscopy revealed that the PEM fibers were solid structures, presumably composed of polyelectrolytes complexed with residual fatty acids. These fibrillar PEM films were found to support the attachment of human dermal fibroblasts. Copyright © 2011 Wiley Periodicals, Inc.

21 CFR 177.2500 - Polyphenylene sulfone resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

... polyphenylene sulfide with peracetic acid such that the finished resins meet the specifications set forth in... glass transition temperature of the polymer is 360±5 °C as determined by the use of differential...

In vitro and in vivo evaluation of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate)/dopamine-coated electrodes for dopamine delivery.

PubMed

Sui, L; Song, X J; Ren, J; Cai, W J; Ju, L H; Wang, Y; Wang, L Y; Chen, M

2014-06-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS) has a variety of chemical and biomedical applications. The application of PEDOT/PSS polymers in drug delivery has attracted attention. However, whether conducting polymers of PEDOT/PSS could be used for dopamine delivery has not clear. In the present study, the PEDOT/PSS coatings incorporated with dopamine were fabricated on 0.5 mm diameter platinum electrodes, electrochemical properties, and dopamine delivery capacities of these electrodes were evaluated in vitro and in vivo through implanting these electrodes into brain striatum area. The findings demonstrated that the PEDOT/PSS/dopamine coatings on platinum electrodes could reduce electrodes impedances, increase charge storage capacities, and release significant levels of dopamine upon electrical stimulation of these electrodes. These results indicated that polymers of PEDOT/PSS/dopamine could be used for dopamine delivery, implicating potential application of PEDOT/PSS/dopamine-coated implantable electrodes in the treatment of some diseases associated with dopamine deficits, such as, electrodes for the treatment of Parkinson's disease during deep brain stimulation. Copyright © 2013 Wiley Periodicals, Inc.

Structure and Dynamics of Ionic Block Copolymer Melts: Computational Study

DOE PAGES

Aryal, Dipak; Agrawal, Anupriya; Perahia, Dvora; ...

2017-09-06

Structure and dynamics of melts of copolymers with an ABCBA topology, where C is an ionizable block, have been studied by fully atomistic molecular dynamics (MD) simulations. Introducing an ionizable block for functionality adds a significant element to the coupled set of interactions that determine the structure and dynamics of the macromolecule. The polymer consists of a randomly sulfonated polystyrene C block tethered to a flexible poly(ethylene-r-propylene) bridge B and end-capped with poly(tert-butylstyrene) A. The chemical structure and topology of these polymers constitute a model for incorporation of ionic blocks within a framework that provides tactility and mechanical stability. Heremore » in this paper we resolve the structure and dynamics of a structured polymer on the nanoscale constrained by ionic clusters. We find that the melts form intertwined networks of the A and C blocks independent of the degree of sulfonation of the C block with no long-range order. The cluster cohesiveness and morphology affect both macroscopic translational motion and segmental dynamics of all the blocks.« less

Structure and Dynamics of Ionic Block Copolymer Melts: Computational Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryal, Dipak; Agrawal, Anupriya; Perahia, Dvora

Structure and dynamics of melts of copolymers with an ABCBA topology, where C is an ionizable block, have been studied by fully atomistic molecular dynamics (MD) simulations. Introducing an ionizable block for functionality adds a significant element to the coupled set of interactions that determine the structure and dynamics of the macromolecule. The polymer consists of a randomly sulfonated polystyrene C block tethered to a flexible poly(ethylene-r-propylene) bridge B and end-capped with poly(tert-butylstyrene) A. The chemical structure and topology of these polymers constitute a model for incorporation of ionic blocks within a framework that provides tactility and mechanical stability. Heremore » in this paper we resolve the structure and dynamics of a structured polymer on the nanoscale constrained by ionic clusters. We find that the melts form intertwined networks of the A and C blocks independent of the degree of sulfonation of the C block with no long-range order. The cluster cohesiveness and morphology affect both macroscopic translational motion and segmental dynamics of all the blocks.« less

Enhanced proton conductivity of proton exchange membranes by incorporating sulfonated metal-organic frameworks

NASA Astrophysics Data System (ADS)

Li, Zhen; He, Guangwei; Zhao, Yuning; Cao, Ying; Wu, Hong; Li, Yifan; Jiang, Zhongyi

2014-09-01

In this study, octahedral crystal MIL101(Cr) with a uniform size of ∼400 nm is synthesized via hydrothermal reaction. It is then functionalized with sulfonic acid groups by concentrated sulfuric acid and trifluoromethanesulfonic anhydride in nitromethane. The sulfonated MIL101(Cr) are homogeneously incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare hybrid membranes. The performances of hybrid membranes are evaluated by proton conductivity, methanol permeability, water uptake and swelling property, and thermal stability. The methanol permeability increased slightly from 6.12 × 10-7 to 7.39 × 10-7 cm2 s-1 with the filler contents increasing from 0 to 10 wt. %. However, the proton conductivity of the hybrid membranes increased significantly. The proton conductivity is increased up to 0.306 S cm-1 at 75 °C and 100% RH, which is 96.2% higher than that of pristine membranes (0.156 S cm-1). The increment of proton conductivity is attributed to the following multiple functionalities of the sulfonated MIL101(Cr) in hybrid membranes: i) providing sulfonic acid groups as facile proton hopping sites; ii) forming additional proton-transport pathways at the interfaces of polymer and MOFs; iii) constructing hydrogen-bonded networks for proton conduction via -OH provided by the hydrolysis of coordinatively unsaturated metal sites.

Investigation of sulfonated polysulfone membranes as electrolyte in a passive-mode direct methanol fuel cell mini-stack

NASA Astrophysics Data System (ADS)

Lufrano, F.; Baglio, V.; Staiti, P.; Stassi, A.; Aricò, A. S.; Antonucci, V.

This paper reports on the development of polymer electrolyte membranes (PEMs) based on sulfonated polysulfone for application in a DMFC mini-stack operating at room temperature in passive mode. The sulfonated polysulfone (SPSf) with two degrees of sulfonation (57 and 66%) was synthesized by a well-known sulfonation process. SPSf membranes with different thicknesses were prepared and investigated. These membranes were characterized in terms of methanol/water uptake, proton conductivity, and fuel cell performance in a DMFC single cell and mini-stack operating at room temperature. The study addressed (a) control of the synthesis of sulfonated polysulfone, (b) optimization of the assembling procedure, (c) a short lifetime investigation and (d) a comparison of DMFC performance in active-mode operation vs. passive-mode operation. The best passive DMFC performance was 220 mW (average cell power density of about 19 mW cm -2), obtained with a thin SPSf membrane (70 μm) at room temperature, whereas the performance of the same membrane-based DMFC in active mode was 38 mW cm -2. The conductivity of this membrane, SPSf (IEC = 1.34 mequiv. g -1) was 2.8 × 10 -2 S cm -1. A preliminary short-term test (200 min) showed good stability during chrono-amperometry measurements.

Theoretical investigation of local proton conductance in the proton exchange membranes

NASA Astrophysics Data System (ADS)

Singh, Raman K.; Tsuneda, Takao; Miyatake, Kenji; Watanabe, Masahiro

2014-07-01

The hydrated structures of the proton exchange membranes were theoretically investigated using long-range corrected density functional theory to make clear why perfluorinated polymer membrane Nafion is superior to other membranes in the proton conductivity at low humidity. For exploring the possibility of the proton conductance in the vehicle mechanism with low hydration numbers, we examined the relay model of protonated water clusters between the sulfonic acid groups in Nafion and concluded that this relay model may contribute to the high proton conductivity of Nafion with less-hydrated sulfonic acid groups.

21 CFR 177.1650 - Polysulfide polymer-polyepoxy resins.

Code of Federal Regulations, 2011 CFR

2011-04-01

...(2-chloroethyl) formal Bis(dichloropropyl) formal Cross-linking agent. Butyl alcohol Solvent. Carbon black (channel process) Chlorinated paraffins Cross-linking agent. Epoxidized linseed oil Epoxidized... monobutyl ether Solvent. Magnesium chloride Methyl isobutyl ketone Solvent. Naphthalene sulfonic acid...

Development of Catechol 2,3-Dioxygenase-Specific Primers for Monitoring Bioremediation by Competitive Quantitative PCR

PubMed Central

Mesarch, Matthew B.; Nakatsu, Cindy H.; Nies, Loring

2000-01-01

Benzene, toluene, xylenes, phenol, naphthalene, and biphenyl are among a group of compounds that have at least one reported pathway for biodegradation involving catechol 2,3-dioxygenase enzymes. Thus, detection of the corresponding catechol 2,3-dioxygenase genes can serve as a basis for identifying and quantifying bacteria that have these catabolic abilities. Primers that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment from eight different bacteria are described. The identities of the amplicons were confirmed by hybridization with a 238-bp catechol 2,3-dioxygenase probe. The detection limit was 102 to 103 gene copies, which was lowered to 100 to 101 gene copies by hybridization. Using the dioxygenase-specific primers, an increase in catechol 2,3-dioxygenase genes was detected in petroleum-amended soils. The dioxygenase genes were enumerated by competitive quantitative PCR with a 163-bp competitor that was amplified using the same primers. Target and competitor sequences had identical amplification kinetics. Potential PCR inhibitors that could coextract with DNA, nonamplifying DNA, soil factors (humics), and soil pollutants (toluene) did not impact enumeration. Therefore, this technique can be used to accurately and reproducibly quantify catechol 2,3-dioxygenase genes in complex environments such as petroleum-contaminated soil. Direct, non-cultivation-based molecular techniques for detecting and enumerating microbial pollutant-biodegrading genes in environmental samples are powerful tools for monitoring bioremediation and developing field evidence in support of natural attenuation. PMID:10653735

Development of catechol 2,3-dioxygenase-specific primers for monitoring bioremediation by competitive quantitative PCR.

PubMed

Mesarch, M B; Nakatsu, C H; Nies, L

2000-02-01

Benzene, toluene, xylenes, phenol, naphthalene, and biphenyl are among a group of compounds that have at least one reported pathway for biodegradation involving catechol 2,3-dioxygenase enzymes. Thus, detection of the corresponding catechol 2,3-dioxygenase genes can serve as a basis for identifying and quantifying bacteria that have these catabolic abilities. Primers that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment from eight different bacteria are described. The identities of the amplicons were confirmed by hybridization with a 238-bp catechol 2,3-dioxygenase probe. The detection limit was 10(2) to 10(3) gene copies, which was lowered to 10(0) to 10(1) gene copies by hybridization. Using the dioxygenase-specific primers, an increase in catechol 2, 3-dioxygenase genes was detected in petroleum-amended soils. The dioxygenase genes were enumerated by competitive quantitative PCR with a 163-bp competitor that was amplified using the same primers. Target and competitor sequences had identical amplification kinetics. Potential PCR inhibitors that could coextract with DNA, nonamplifying DNA, soil factors (humics), and soil pollutants (toluene) did not impact enumeration. Therefore, this technique can be used to accurately and reproducibly quantify catechol 2, 3-dioxygenase genes in complex environments such as petroleum-contaminated soil. Direct, non-cultivation-based molecular techniques for detecting and enumerating microbial pollutant-biodegrading genes in environmental samples are powerful tools for monitoring bioremediation and developing field evidence in support of natural attenuation.

An investigation of long and short range ion motions within the cluster morphology of electrolyte-containing perfluoro-sulfonate ionomer membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, S.

1992-01-01

An equivalent circuit model was postulated for PFSI (perfluoro-sulfanate-ionomer) polymers. It successfully models three different dielectric relaxation mechanisms taking place within long and short sidechain PFSI's in an alternating electric field. The three dielectric processes are long-range ion inter-cluster hopping in the low frequency region, short-range intra-cluster polarization occurred in frequencies at about 10[sup 3] to 10[sup 6] Hz, and Debye-like orientation of water molecules taking place at very high frequencies. When membranes are annealed in the proximity of the glass transition temperature of ionic clusters, the packing of sulfonate groups becomes more efficient. This is by the fact thatmore » the symmetrical parameter of the distribution of relaxation time of the Cole-Cole equation increases with annealing time. The cluster activities of the long and short sidechain polymers act differently in different electrolyte solutions. The sidechains of the long sidechain polymer act like a spring, it contracts while the material was equilibrated in low concentration solutions and it expands as equilibrated in concentrated solutions. The cluster dimension of the long sidechain material does not vary too much. The cluster dimension of short sidechain polymers can vary significantly on different electrolyte solutions.« less

Passivation-free solid state battery

DOEpatents

Abraham, Kuzhikalail M.; Peramunage, Dharmasena

1998-01-01

This invention pertains to passivation-free solid-state rechargeable batteries composed of Li.sub.4 Ti.sub.5 O.sub.12 anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn.sub.2 O.sub.4, LiCoO.sub.2, LiNiO.sub.2 and LiV.sub.2 O.sub.5 and their derivatives.

Low Permeable Hydrocarbon Polymer Electrolyte Membrane for Vanadium Redox Flow Battery.

PubMed

Jung, Ho-Young; Moon, Geon-O; Jung, Seunghun; Kim, Hee Tak; Kim, Sang-Chai; Roh, Sung-Hee

2017-04-01

Polymer electrolyte membrane (PEM) confirms the life span of vanadium redox flow battery (VRFB). Products from Dupont, Nafion membrane, is mainly used for PEM in VRFB. However, permeation of vanadium ion occurs because of Nafion’s high permeability. Therefore, the efficiency of VRFB decreases and the prices becomes higher, which hinders VRFB’s commercialization. In order to solve this problem, poly(phenylene oxide) (PPO) is sulfonated for the preparation of low-priced hydrocarbon polymer electrolyte membrane. sPPO membrane is characterized by fundamental properties and VRFB cell test.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Hui; Wei, Yang; Wang, Cheng

The excessive volume changes during cell cycling of Si-based anode in lithium ion batteries impeded its application. One major reason for the cell failure is particle isolation during volume shrinkage in delithiation process, which makes strong adhesion between polymer binder and anode active material particles a highly desirable property. Here, a biomimetic side-chain conductive polymer incorporating catechol, a key adhesive component of the mussel holdfast protein, was synthesized. Atomic force microscopy-based single-molecule force measurements of mussel-inspired conductive polymer binder contacting a silica surface revealed a similar adhesion toward substrate when compared with an effective Si anode binder, homo-poly(acrylic acid), withmore » the added benefit of being electronically conductive. Electrochemical experiments showed a very stable cycling of Si-alloy anodes realized via this biomimetic conducting polymer binder, leading to a high loading Si anode with a good rate performance. We attribute the ability of the Si-based anode to tolerate the volume changes during cycling to the excellent mechanical integrity afforded by the strong interfacial adhesion of the biomimetic conducting polymer.« less

Activation of Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol) using a Supramolecular Trigger†

PubMed Central

Phillips, Daniel J.; Congdon, Thomas R.; Gibson, Matthew I.

2016-01-01

Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity – a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization. Upon addition of Fe3+, larger supramolecular star polymers form by assembly with two or three catechols. This increase in molecular weight effectively ‘switches on’ the IRI activity and is the first example of external control over the function of AFP mimetics. This provides a simple but elegant solution to the challenge of external control of AFP-mimetic function. PMID:28003855

Bio-inspired reversible underwater adhesive.

PubMed

Zhao, Yanhua; Wu, Yang; Wang, Liang; Zhang, Manman; Chen, Xuan; Liu, Minjie; Fan, Jun; Liu, Junqiu; Zhou, Feng; Wang, Zuankai

2017-12-20

The design of smart surfaces with switchable adhesive properties in a wet environment has remained a challenge in adhesion science and materials engineering. Despite intense demands in various industrial applications and exciting progress in mimicking the remarkable wet adhesion through the delicate control of catechol chemistry, polyelectrolyte complex, and supramolecular architectures, the full recapitulation of nature's dynamic function is limited. Here, we show a facile approach to synthesize bioinspired adhesive, which entails the reversible, tunable, and fast regulation of the wet adhesion on diverse surfaces. The smart wet adhesive takes advantage of the host-guest molecular interaction and the adhesive nature of catechol chemistry, as well as the responsive polymer, allowing for screening and activation of the interfacial interaction simply by a local temperature trigger in an on-demand manner. Our work opens up an avenue for the rational design of bioinspired adhesives with performances even beyond nature.

Thickening compositions, and related materials and processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, Michael Joseph; Perry, Robert James; Enick, Robert Michael

A silicone polymer is provided, modified with at least one functional group from the class of anthraquinone amide groups; anthraquinone sulfonamide groups; thioxanthone amide groups; or thioxanthone sulfone amide groups. The polymer can be combined with a hydrocarbon solvent or with supercritical carbon dioxide (CO.sub.2), and is very effective for increasing the viscosity of either medium. A process for the recovery of oil from a subterranean, oil-bearing formation is also described, using supercritical carbon dioxide modified with the functionalized silicone polymer. A process for extracting natural gas or oil from a bedrock-shale formation is also described, again using the modifiedmore » silicone polymer.« less

Sulfonated poly(styrene-divinylbenzene) modified with amines and the application for pipette-tip solid-phase extraction of carbendazim in apples.

PubMed

Ma, Yuxin; Liu, Lingling; Tang, Weiyang; Zhu, Tao

2017-10-01

Sulfonated poly(styrene-divinylbenzene) modified with five kinds of amine functional groups was applied to the determination of carbendazim in apple samples with a pipette-tip solid-phase extraction method. The structures of the polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Five different modifications of the solid-phase extraction sorbent based on sulfonated poly(styrene-divinylbenzene) were tested under static and pipette-tip solid-phase extraction conditions. The polymer modified with p-methoxyaniline showed the best recognition capacity and adsorption amount for carbendazim. Under the optimum conditions, 3.00 mg of the adsorbent, 1.00 mL of ethyl acetate as washing solvent, and 1.00 mL of ammonia/acetonitrile (5:95, v/v) as elution solvent were used in the pretreatment procedure of apple samples. The calibration graphs of carbendazim in methanol were linear over 5.00-200.00 μg/mL, and the limits of detection and quantification were 0.01 and 0.03 μg/mL, respectively. The method recoveries of carbendazim were in the range of 91.31-98.13% with associated intraday relative standard deviations of 0.76-2.13% and interday relative standard deviations of 1.10-1.85%. Sulfonated poly(styrene-divinylbenzene) modified with p-methoxyaniline showed satisfactory results (recovery: 97.96%) and potential for the rapid purification of carbendazim in apple samples combined with the pipette-tip solid-phase extraction. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement of electrochemical performances of sulfonated poly(arylene ether sulfone) via incorporation of sulfonated poly(arylene ether benzimidazole)

NASA Astrophysics Data System (ADS)

Hong, Young Taik; Lee, Chang Hyun; Park, Hyung Su; Min, Kyung A.; Kim, Hyung Joong; Nam, Sang Yong; Lee, Young Moo

In the present study, modified acid-base blend membranes were fabricated via incorporation of sulfonated poly(arylene ether benzimidazole) (SPAEBI) into sulfonated poly(arylene ether sulfone) (SPAES). These membranes had excellent methanol-barrier properties in addition to an ability to compensate for the loss of proton conductivity that typically occurs in general acid-base blend system. To fabricate the membranes, SPAEBIs, which served as amphiphilic polymers with different degrees of sulfonation (0-50 mol%), were synthesized by polycondensation and added to SPAES. It resulted in the formation of acid-amphiphilic complexes such as [PAES-SO 3] - +[H-SPAEBI] through the ionic crosslinking, which prevented SO 3H groups in the complex from transporting free protons in an aqueous medium, contributing to a reduction of ion exchange capacity values and water uptake in the blend membranes, and leading to lower methanol permeability in a water-methanol mixture. Unfortunately, the ionic bonding formation was accompanied by a decrease of bound water content and proton conductivity, although the latter problem was solved to some extent by the incorporation of additional SO 3H groups in SPAEBI. In the SPAES-SPAEBI blend membranes, enhancement of proton conductivity and methanol-barrier property was prominent at temperatures over 90 °C. The direct methanol fuel cell (DMFC) performance, which was based on SPAES-SPAEBI-50-5, was 1.2 times higher than that of Nafion ® 117 under the same operating condition.

Electroactive nanostructured polymer actuators fabricated using sulfonated styrenic pentablock copolymer/montmorillonite/ionic liquid nanocomposite membranes

NASA Astrophysics Data System (ADS)

Lee, Jang-Woo; Hong, Soon Man; Koo, Chong Min

2014-08-01

High-bendable, air-operable ionic polymer-metal composite (IPMC) actuators composed of electroactive nanostructured middle-block sulfonated styrenic pentablock copolymer (SSPB)/sulfonated montmorillonite (s-MMT) nanocomposite electrolyte membranes with bulky imidazolium ionic liquids (ILs) incorporated were fabricated and their bending actuation performances were evaluated. The SSPB-based IPMC actuators showed larger air-operable bending displacements, higher displacement rates, and higher energy efficiency of actuations without conventional IPMC bottlenecks, including back relaxation and actuation instability during actuation in air, than the Nafion counterpart. Incorporation of s-MMT into the SSPB matrix further enhanced the actuation performance of the IPMC actuators in terms of displacement, displacement rate, and energy efficiency. The remarkably high performance of the SSPB/s-MMT/IL IPMCs was considered to be due to the microphase-separated large ionic domains of the SSPB (the average diameter of the ionic domain: ca. 20 nm) and the role of s-MMT as an ionic bridge between the ionic domains, and the ion pumping effect of the bulky imidazolium cations of the ILs as well. The microphase-separated nanostructure of the composite membranes caused a high dimensional stability upon swelling in the presence of ILs, which effectively preserved the original electrode resistance against swelling, leading to a high actuation performance of IPMC.

Photogalvanic cells driven by electron transfer quenching of excited singlet states

NASA Astrophysics Data System (ADS)

Creed, D.; Fawcett, N. C.

Photoreduction of oxonine by iron(II) sulfate in dilute acid is produced by quenching of the excited signlet state (S1). No induced intersystem crossing to the tripolet (T1) is observed by nanosecond flash photolysis. The photoreduction of oxonine (S1) by iron(II) was used in a totally illuminated thin layer photogalvanic cell. Power conversion efficiencies are, however, very low. The fluorescence of oxonine and thiazine dyes such as thionine is quenched by acids. Oxonine fluorescence is also quenched by hydroquinone and catechol sulfonates and related compounds. Eleven new thiazine dyes were synthesized. A few photogalvanic experiments were carried out using high concentrations of the water miscible dye and iron(II) in a TI/TL cell. Ferrophos, an iron phosphorus alloy, can be substituted for platinum or gold as a cathode in photogalvanic cells.

Preparation, Characterization and Utilization of Electrodes Coated with Polymeric Networks Formed by Gamma Radiation Crosslinking.

DTIC Science & Technology

1987-04-01

polymers such as poly[ diallyl dimethyl ammonium chloride] , poly [vinylbenzyl trimethyl ammonium chloride], poly[styrene sulfonic acid , sodium salt] and...poly[acrylic acid ], which would ordinarily dissolve from the electrode surface in aqueous solution unless crosslinked into a network, and several...Irradiation on a Water-Soluble Polymer: DDAC 8 E. Electrochemistry of DDAC Networks on Platinum and Graphite 10 F. Poly [acrylic acid ] Films on Graphite

Mussel-Inspired Conductive Polymer Binder for Si-Alloy Anode in Lithium-Ion Batteries

DOE PAGES

Zhao, Hui; Wei, Yang; Wang, Cheng; ...

2018-01-15

The excessive volume changes during cell cycling of Si-based anode in lithium ion batteries impeded its application. One major reason for the cell failure is particle isolation during volume shrinkage in delithiation process, which makes strong adhesion between polymer binder and anode active material particles a highly desirable property. Here, a biomimetic side-chain conductive polymer incorporating catechol, a key adhesive component of the mussel holdfast protein, was synthesized. Atomic force microscopy-based single-molecule force measurements of mussel-inspired conductive polymer binder contacting a silica surface revealed a similar adhesion toward substrate when compared with an effective Si anode binder, homo-poly(acrylic acid), withmore » the added benefit of being electronically conductive. Electrochemical experiments showed a very stable cycling of Si-alloy anodes realized via this biomimetic conducting polymer binder, leading to a high loading Si anode with a good rate performance. We attribute the ability of the Si-based anode to tolerate the volume changes during cycling to the excellent mechanical integrity afforded by the strong interfacial adhesion of the biomimetic conducting polymer.« less

Process for the displacement of cyanide ions from metal-cyanide complexes

DOEpatents

Smith, Barbara F.; Robinson, Thomas W.

1997-01-01

The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

Performance assessment of polymer based electrodes for in vitro electrophysiological sensing: the role of the electrode impedance

NASA Astrophysics Data System (ADS)

Medeiros, Maria C. R.; Mestre, Ana L. G.; Inácio, Pedro M. C.; Santos, José M. L.; Araujo, Inês M.; Bragança, José; Biscarini, Fabio; Gomes, Henrique L.

2016-09-01

Conducting polymer electrodes based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are used to record extracellular signals from autonomous cardiac contractile cells and glioma cell cultures. The performance of these conducting polymer electrodes is compared with Au electrodes. A small-signal impedance analysis shows that in the presence of an electrolyte, both Au and polymer electrodes establish high capacitive double-layers. However, the polymer/electrolyte interfacial resistance is 3 orders of magnitude lower than the resistance of the metal/electrolyte interface. The polymer low interfacial resistance minimizes the intrinsic thermal noise and increases the system sensitivity. However, when measurements are carried out in current mode a low interfacial resistance partially acts as a short circuit of the interfacial capacitance, this affects the signal shape.

Fabrication of composite membranes using copper metal organic framework for energy application

NASA Astrophysics Data System (ADS)

Gahlot, Swati; Rajput, Abhishek; Kulshrestha, Vaibhav

2018-04-01

Present manuscript deals with the synthesis of nanocomposite polymer electrolyte membrane (PEM) based on copper based metal organic framework (Cu-MOF) and sulfonated poly ether sulfone (SPES) for fuel cell application. Prepared material and composite membrane has been analyzed through various techniques. Structural and thermal characterization of prepared material has been carried out through XRD, FTIR and TGA technique. Measurement shows the successful synthesis of MOF and also confirms the thermal stability. Prepared membranes shows good physicochemical properties and good ionic conductivity which can be utilized as PEM for fuel cell application.

Durability and degradation analysis of hydrocarbon ionomer membranes in polymer electrolyte fuel cells accelerated stress evaluation

NASA Astrophysics Data System (ADS)

Shimizu, Ryo; Tsuji, Junichi; Sato, Nobuyuki; Takano, Jun; Itami, Shunsuke; Kusakabe, Masato; Miyatake, Kenji; Iiyama, Akihiro; Uchida, Makoto

2017-11-01

The chemical durabilities of two proton-conducting hydrocarbon polymer electrolyte membranes, sulfonated benzophenone poly(arylene ether ketone) (SPK) semiblock copolymer and sulfonated phenylene poly(arylene ether ketone) (SPP) semiblock copolymer are evaluated under accelerated open circuit voltage (OCV) conditions in a polymer electrolyte fuel cell (PEFC). Post-test characterization of the membrane electrodes assemblies (MEAs) is carried out via gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. These results are compared with those of the initial MEAs. The SPP cell shows the highest OCV at 1000 h, and, in the post-test analysis, the SPP membrane retains up to 80% of the original molecular weight, based on the GPC results, and 90% of the hydrophilic structure, based on the NMR results. The hydrophilic structure of the SPP membrane is more stable after the durability evaluation than that of the SPK. From these results, the SPP membrane, with its simple hydrophilic structure, which does not include ketone groups, is seen to be significantly more resistant to radical attack. This structure leads to high chemical durability and thus impedes the chemical decomposition of the membrane.

Chemically Modified Polyvinyl Chloride for Removal of Thionine Dye (Lauth’s Violet)

PubMed Central

Silva, Cleuzilene V.; Royer, Betina; Rodrigues Filho, Guimes; Cerqueira, Daniel A.; Assunção, Rosana M. N.

2017-01-01

The chemical modification of hydrophobic polymer matrices is an alternative way to elchange their surface properties. The introduction of sulfonic groups in the polymer changes the surface properties such as adhesion, wettability, catalytic ability, and adsorption capacity. This work describes the production and application of chemically modified polyvinyl chloride (PVC) as adsorbent for dyes removal. Chemical modification of PVC was evaluated by infrared spectroscopy and elemental analysis, which indicated the presence of sulfonic groups on PVC. The chemically modified PVC (PVCDS) showed an ion exchange capacity of 1.03 mmol−1, and efficiently removed the thionine dye (Lauth’s violet) from aqueous solutions, reaching equilibrium in 30 min. The adsorption kinetics was better adjusted for a pseudo second order model. This result indicates that the adsorption of thionine onto PVCDS occurs by chemisorption. Among the models for the state of equilibrium, SIPS and Langmuir exhibited the best fit to the experimental results and PVCDS showed high adsorption capacities (370 mg−1). Thus, it is assumed that the system presents homogeneous characteristics to the distribution of active sites. The modification promoted the formation of surface characteristics favorable to the dye adsorption by the polymer. PMID:29137158

Polybenzimidazole (PBI) functionalized nanographene as highly stable catalyst support for polymer Electrolyte membrane fuel cells (PEMFCs)

DOE PAGES

Xin, Le; Yang, Fan; Qiu, Yang; ...

2016-08-25

Nanoscale graphenes were used as cathode catalyst supports in proton exchange membrane fuel cells (PEMFCs). Surface-initiated polymerization that covalently bonds polybenzimidazole (PBI) polymer on the surface of graphene supports enables the uniform distribution of the Pt nanoparticles, as well as allows the sealing of the unterminated carbon bonds usually present on the edge of graphene from the chemical reduction of graphene oxide. The nanographene effectively shortens the length of channels and pores for O 2 diffusion/water dissipation and significantly increases the primary pore volume. Further addition of p-phenyl sulfonic functional graphitic carbon particles as spacers, increases the specific volume ofmore » the secondary pores and greatly improves O 2 mass transport within the catalyst layers. The developed composite cathode catalyst of Pt/PBI-nanographene (50 wt%) + SO 3H-graphitic carbon black demonstrates a higher beginning of life (BOL) PEMFC performance as compared to both Pt/PBI-nanographene (50 wt%) and Pt/PBI-graphene (50 wt%) + SO 3H-graphitic carbon black (GCB). Accelerated stress tests show excellent support durability compared to that of traditional Pt/Vulcan XC72 catalysts, when subjected to 10,000 cycles from 1.0 V to 1.5 V. As a result, this study suggests the promise of using PBI-nanographene + SO 3H-GCB hybrid supports in fuel cells to achieve the 2020 DOE targets for transportation applications.« less

Passivation-free solid state battery

DOEpatents

Abraham, K.M.; Peramunage, D.

1998-06-16

This invention pertains to passivation-free solid-state rechargeable batteries composed of Li{sub 4}Ti{sub 5}O{sub 12} anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2} and LiV{sub 2}O{sub 5} and their derivatives. 5 figs.

New Fluorinated and Sulfonated Block Copolymers Final Report

DTIC Science & Technology

2009-04-23

use polymers namely, Polymer Electrolyte Membrane Fuel Cells ( PEMFC ) and Direct Methanol Fuel Cells (DMFC) The DMFC can be seen as a variant of...the PEMFC . The membranes are typically the same; however, the feed for DMFC is methanol in an aqueous 1-2 M solution or in its vapor form. This fuel...the existing liquid fuels infrastructure can be used for methanol. Catalysts, as well as operating temperature ranges, are very similar to the PEMFC

Recent advances in the chemical modification of unsaturated polymers

NASA Technical Reports Server (NTRS)

Schulz, D. N.; Turner, S. R.; Golub, M. A.

1982-01-01

The present discussion has the objective to update the most comprehensive reviews on the considered subject and to fill in the gaps of less complete, but more modern treatments. Only simple chemical functionalization or structural modification of unsaturated polymers are covered, and the literature of diene polymer modification since 1974 is emphasized. Attention is given to hydrogenation, halogenation and hydrohalogenation, cyclization, cis-trans isomerization, epoxidation, ene and other cycloaddition reactions, sulfonation, carboxylation, phosphonylation, sulfenyl chloride addition, carbene addition, metalation, and silylation. It is pointed out that modern synthetic reagents and catalysts have been advantageously employed to improve process and/or product quality. Synthetic techniques have been refined to allow the selective modification of specific polymer microstructures or blocks.

Colitis induced by sodium polystyrene sulfonate in sorbitol: A report of six cases.

PubMed

Jacob, Sheba S K; Parameswaran, Ashok; Parameswaran, Sarojini Ashok; Dhus, Ubal

2016-03-01

Drug-related injury has been noted in virtually all organ systems, and recognition of the patterns of injury associated with medication enables modification of treatment and reduces the morbidity associated with the side effects of drugs. With the large number of new drugs being developed, documentation of the morphology of the changes seen as an adverse effect becomes important to characterize the pattern of injury. The pathologist is often the first to identify these abnormalities and correlate them with a particular drug. Kayexalate or sodium polystyrene sulfonate (SPS), a linear polymer derived from polystyrene containing sulfonic acid and sulfonate functional groups is used to treat hyperkalemia. It is usually administered with an osmotic laxative sorbitol orally or as retention enema. This combination has been implicated in causing damage to different parts of the gastrointestinal (GI) tract especially the colon and causes an established pattern of injury, recognizable by the presence of characteristic crystals, is presented to create a greater awareness of the Kayexalate colitis. This entity should be included in the differential diagnosis of lower GI mucosal injury in a setting of uremia and hyperkalemia.

Three-dimensional activated graphene network-sulfonate-terminated polymer nanocomposite as a new electrode material for the sensitive determination of dopamine and heavy metal ions.

PubMed

Yuan, Xiaoyan; Zhang, Yijia; Yang, Lu; Deng, Wenfang; Tan, Yueming; Ma, Ming; Xie, Qingji

2015-03-07

We report here that three-dimensional activated graphene networks (3DAGNs) are a better matrix to prepare graphene-polymer nanocomposites for sensitive electroanalysis than two-dimensional graphene nanosheets (2DGNs). 3DAGNs were synthesized in advance by the direct carbonization and simultaneous chemical activation of a cobalt ion-impregnated D113-type ion exchange resin, which showed an interconnected network structure and a large specific surface area. Then, the 3DAGN-sulfonate-terminated polymer (STP) nanocomposite was prepared via the in situ chemical co-polymerization of m-aminobenzene sulfonic acid and aniline in the presence of 3DAGNs. The 3DAGN-STP nanocomposite can adsorb dopamine (DA) and heavy metal ions, which was confirmed by quartz crystal microbalance studies. The 3DAGN-STP modified glassy carbon electrode (GCE) was used for the electrochemical detection of DA in the presence of ascorbic acid and uric acid, with a linear response range of 0.1-32 μM and a limit of detection of 10 nM. In addition, differential pulse voltammetry was used for the simultaneous determination of Cd(2+) and Pb(2+) at the 3DAGN-STP/GCE further modified with a bismuth film, exhibiting linear response ranges of 1-70 μg L(-1) for Cd(2+) and 1-80 μg L(-1) for Pb(2+) with limits of detection of 0.1 μg L(-1) for Cd(2+) and 0.2 μg L(-1) for Pb(2+). Because the 3DAGN-STP can integrate the advantages of 3DAGNs with STPs, the 3DAGN-STP/GCE was more sensitive than the bare GCE, 3DAGN/GCE, and 2DGN-STP/GCE for the determination of DA and heavy metal ions.

OMS-2-Supported Cu Hydroxide-Catalyzed Benzoxazoles Synthesis from Catechols and Amines via Domino Oxidation Process at Room Temperature.

PubMed

Meng, Xu; Wang, Yanmin; Wang, Yuanguang; Chen, Baohua; Jing, Zhenqiang; Chen, Gexin; Zhao, Peiqing

2017-07-07

In the presence of manganese oxide octahedral molecular sieve (OMS-2) supported copper hydroxide Cu(OH) x /OMS-2, aerobic synthesis of benzoxazoles from catechols and amines via domino oxidation/cyclization at room temperature is achieved. This heterogeneous benzoxazoles synthesis initiated by the efficient oxidation of catechols over Cu(OH) x /OMS-2 tolerates a variety of substrates, especially amines containing sensitive groups (hydroxyl, cyano, amino, vinyl, ethynyl, ester, and even acetyl groups) and heterocycles, which affords functionalized benzoxazoles in good to excellent yields by employing low catalyst loading (2 mol % Cu). The characterization and plausible catalytic mechanism of Cu(OH) x /OMS-2 are described. The notable features of our catalytic protocol such as the use of air as the benign oxidant and EtOH as the solvent, mild conditions, ease of product separation, being scalable up to the gram level, and superior reusability of catalyst (up to 10 cycles) make it more practical and environmentally friendly for organic synthesis.

Fluoride sensing by catechol-based π-electron systems.

PubMed

An, Byeong-Kwan; Wang, Xin; Burn, Paul L; Meredith, Paul

2010-11-15

We have developed new catechol-based sensors that can detect fluoride via fluorescence or optical absorption even in the presence of other halides. The level and sensitivity of detection of the sensing molecules is dependent on the chromophore length, which is controlled by the number of thiophene units (one to three) within the chromophore. The sensor with three thiophene units, (E)-2-(2,2'-terthiophen-5-yl)-3-(3,4-dihydroxyphenyl)acrylonitrile, gives the best response to fluoride. By using fluorescence measurements fluoride is detectable over the concentration range 1.7 μM to 200 μM. Importantly, when adsorbed onto a solid support the fluorescent catechol dye can be used to detect the presence of fluoride in aqueous solution.

Polyaniline nanotubes and their dendrites doped with different naphthalene sulfonic acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Zhiming; Chemistry and Chemical Engineering College, Ocean University of China, Qingdao 266003; Wei Zhixiang

2005-03-01

Polyaniline (PANI) nanotubes (130-250 nm in average diameter) doped with {alpha}-naphthalene sulfonic acid ({alpha}-NSA), {beta}-naphthalene sulfonic acid ({beta}-NSA) and 1,5-naphthalene disulfonic acid were synthesized via a self-assembly process. It was found that the formation yield, morphology (hollow or solid), size, crystalline and electrical properties of the nanostructures are affected by the position and number of -SO{sub 3}H groups attached to the naphthalene ring of NSA as well as the synthesis conditions. Moreover, these nanotubes aggregate to form a dendritic morphology when the polymerization is performed at a static state. The micelles composed of dopant or dopant/anilinium cations might act inmore » a template-like fashion in forming self-assembled PANI nanotubes, which was further confirmed by X-ray diffraction measurements, while the aggregated morphology of the nanotubes might result from polymer chain interactions including {pi}-{pi} interactions, hydrogen and ionic bonds.« less

The effect of ionic membrane properties on the performance of ionic polymer-metal composite (IPMC) actuator

NASA Astrophysics Data System (ADS)

Jho, Jae Y.; Han, Man J.; Park, Jong H.; Lee, Jang Y.; Wang, Hyuck S.

2005-05-01

On purpose to overcome the limit of conventional ionic polymer-metal composites (IPMC) using the commercial ionic membranes, novel IPMCs with radiation-grafted ion-exchange membranes were prepared. Poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-co-HFP) and poly(ethylene-co-tetrafluoroethylene) (ETFE) were radiation-grafted with styrene, and then sulfonated. The properties of the membranes were modulated by controlling the amount of polystyrene sulfonic acid (PSSA) groups in the membranes. The amount of PSSA groups were tuned by controlling the total absorbed dose of γ-ray. The membranes were characterized by measuring the water-uptake, the ion-exchange capacity, and the ion conductivity. The performance of the IPMCs using these membranes were analyzed with laser displacement meter. They exhibited much larger bending displacement in comparison with Nafion-based IPMC. With increasing the amount of PSSA groups, the maximum displacement and the bending speed were remarkably increased. The results made sure that the property of ion-exchange membrane was the key element affecting the actuation performance of IPMC.

Cluster Morphology-Polymer Dynamics Correlations in Sulfonated Polystyrene Melts: Computational Study

DOE PAGES

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S.

2016-04-11

Reaching exceptionally long times up to 500 ns in equilibrium and nonequilibrium molecular dynamics simulations studies, we have attained a fundamental molecular understanding of the correlation of ionomer clusters structure and multiscale dynamics, providing new insight into one critical, long-standing challenge in ionic polymer physics. The cluster structure in melts of sulfonated polystyrene with Na + and Mg 2+ counterions are resolved and correlated with the dynamics on multiple length and time scales extracted from measurements of the dynamic structure factor and shear rheology. We find that as the morphology of the ionic clusters changes from ladderlike for Na +more » to disordered structures for Mg 2+, the dynamic structure factor is affected on the length scale corresponding to the ionic clusters. Lastly, rheology studies show that the viscosity for Mg 2+ melts is higher than for Na + ones for all shear rates, which is well correlated with the larger ionic clusters’ size for the Mg 2+ melts.« less

Transparent Wood Smart Windows: Polymer Electrochromic Devices Based on Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate) Electrodes.

PubMed

Lang, Augustus W; Li, Yuanyuan; De Keersmaecker, Michel; Shen, D Eric; Österholm, Anna M; Berglund, Lars; Reynolds, John R

2018-03-09

Transparent wood composites, with their high strength and toughness, thermal insulation, and excellent transmissivity, offer a route to replace glass for diffusely transmitting windows. Here, conjugated-polymer-based electrochromic devices (ECDs) that switch on-demand are demonstrated using transparent wood coated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a transparent conducting electrode. These ECDs exhibit a vibrant magenta-to-clear color change that results from a remarkably colorless bleached state. Furthermore, they require low energy and power inputs of 3 mWh m -2 at 2 W m -2 to switch due to a high coloration efficiency (590 cm 2  C -1 ) and low driving voltage (0.8 V). Each device component is processed with high-throughput methods, which highlights the opportunity to apply this approach to fabricate mechanically robust, energy-efficient smart windows on a large scale. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Semi-interpenetrating polymer network proton exchange membranes with narrow and well-connected hydrophilic channels

NASA Astrophysics Data System (ADS)

Fang, Chunliu; Toh, Xin Ni; Yao, Qiaofeng; Julius, David; Hong, Liang; Lee, Jim Yang

2013-03-01

Four series of semi-interpenetrating polymer network (SIPN) membranes are fabricated by thermally cross-linking aminated BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide)) with different epoxide cross-linkers in the presence of sulfonated PPO (SPPO). The cross-link structure and hydrophobicity are found to impact the membrane morphology strongly - smaller and more hydrophobic cross-links form narrow and well-connected hydrophilic channels whereas bulky and less hydrophobic cross-links form wide but less-connected hydrophilic channels. The membranes of the former can support facile proton transport and suppress methanol crossover to result in higher proton conductivity and lower methanol permeability than the membranes of the latter. The membranes are also fabricated into membrane electrode assemblies (MEAs) and tested in single-stack direct methanol fuel cells (DMFCs). It is found that some of these SIPN membranes can surpass Nafion® 117 in maximum power density, demonstrating their potential as a proton exchange membrane (PEM) for the DMFCs.

Biochemical synthesis of water soluble conducting polymers

NASA Astrophysics Data System (ADS)

Bruno, Ferdinando F.; Bernabei, Manuele

2016-05-01

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

Electronic and transport properties of Cobalt-based valence tautomeric molecules and polymers

NASA Astrophysics Data System (ADS)

Chen, Yifeng; Calzolari, Arrigo; Buongiorno Nardelli, Marco

2011-03-01

The advancement of molecular spintronics requires further understandings of the fundamental electronic structures and transport properties of prototypical spintronics molecules and polymers. Here we present a density functional based theoretical study of the electronic structures of Cobalt-based valence tautomeric molecules Co III (SQ)(Cat)L Co II (SQ)2 L and their polymers, where SQ refers to the semiquinone ligand, and Cat the catecholate ligand, while L is a redox innocent backbone ligand. The conversion from low-spin Co III ground state to high-spin Co II excited state is realized by imposing an on-site potential U on the Co atom and elongating the Co-N bond. Transport properties are subsequently calculated by extracting electronic Wannier functions from these systems and computing the charge transport in the ballistic regime using a Non-Equilibrium Green's Function (NEGF) approach. Our transport results show distinct charge transport properties between low-spin ground state and high-spin excited state, hence suggesting potential spintronics devices from these molecules and polymers such as spin valves.

Ion-Conducting Organic/Inorganic Polymers

NASA Technical Reports Server (NTRS)

Kinder, James D.; Meador, Mary Ann B.

2007-01-01

Ion-conducting polymers that are hybrids of organic and inorganic moieties and that are suitable for forming into solid-electrolyte membranes have been invented in an effort to improve upon the polymeric materials that have been used previously for such membranes. Examples of the prior materials include perfluorosulfonic acid-based formulations, polybenzimidazoles, sulfonated polyetherketone, sulfonated naphthalenic polyimides, and polyethylene oxide (PEO)-based formulations. Relative to the prior materials, the polymers of the present invention offer greater dimensional stability, greater ease of formation into mechanically resilient films, and acceptably high ionic conductivities over wider temperature ranges. Devices in which films made of these ion-conducting organic/inorganic polymers could be used include fuel cells, lithium batteries, chemical sensors, electrochemical capacitors, electrochromic windows and display devices, and analog memory devices. The synthesis of a polymer of this type (see Figure 1) starts with a reaction between an epoxide-functionalized alkoxysilane and a diamine. The product of this reaction is polymerized by hydrolysis and condensation of the alkoxysilane group, producing a molecular network that contains both organic and inorganic (silica) links. The silica in the network contributes to the ionic conductivity and to the desired thermal and mechanical properties. Examples of other diamines that have been used in the reaction sequence of Figure 1 are shown in Figure 2. One can use any of these diamines or any combination of them in proportions chosen to impart desired properties to the finished product. Alternatively or in addition, one could similarly vary the functionality of the alkoxysilane to obtain desired properties. The variety of available alkoxysilanes and diamines thus affords flexibility to optimize the organic/inorganic polymer for a given application.

Metabolism of benzene, toluene, and xylene hydrocarbons in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsao, C.W.; Song, H.G.; Bartha, R.

Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted the authors to investigate the metabolism of {sup 14}C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically replenished any O{sub 2} consumed. The decrease in solvent vapors and the production of {sup 14}CO{sub 2} were monitored. At the conclusion of each experiment, {sup 14}C distribution in solvent-extractable polymers, biomass, and humic material was determined, obtaining {supmore » 14}C mass balances of 85 to 98%. BTX compounds were extensively mineralized in soil, regardless of whether they were presented singly or in combinations. No evidence was obtained for the formation of solvent-extractable polymers from xylenes in soil, but {sup 14}C distribution in biomass and humus was unusual for all BTX compounds and especially for toluene and the xylenes. The results suggest that catechol intermediates of BTX degradation are preferentially polymerized into the soil humus and that the methyl substituents of the catechols derived from toluene and especially from xylenes enhance this incorporation. In contrast to inhibitory residues formed from xylene cometabolism in culture, the humus-incorporated xylene residues showed no significant toxicity in the Microtox assay.« less

Polyphosphazine-based polymer materials

DOEpatents

Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

2010-05-25

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Automated solid-phase radiofluorination using polymer-supported phosphazenes.

PubMed

Mathiessen, Bente; Zhuravlev, Fedor

2013-08-30

The polymer supported phosphazene bases PS-P₂(tBu) and the novel PS-P₂(PEG) allowed for efficient extraction of [¹⁸F]F⁻ from proton irradiated [¹⁸O]H₂O and subsequent radiofluorination of a broad range of substrates directly on the resin. The highest radiochemical yields were obtained with aliphatic sulfonates (69%) and bromides (42%); the total radiosynthesis time was 35-45 min. The multivariate analysis showed that the radiochemical yields and purities were controlled by the resin load, reaction temperature, and column packing effects. The resins could be reused several times with the same or different substrates. The fully automated on-column radiofluorination methodology was applied to the radiosynthesis of the important PET radiotracers [¹⁸F]FLT and [¹⁸F]FDG. The latter was produced with 40% yield on a 120 GBq scale and passed GMP-regulated quality control required for commercial production of [1¹⁸F]FDG. The combination of compact form factor, simplicity of [¹⁸F]F⁻ recovery and processing, and column reusability can make solid phase radiofluorination an attractive radiochemistry platform for the emerging dose-on-demand instruments for bedside production of PET radiotracers.

Acquisition of a SAXS Facility for the Study of Novel Polymer Nanocomposite Membranes

DTIC Science & Technology

2015-02-19

at the 2015 MRS Spring National Meeting, San Francisco , CA, April, 2015. 2. A. Millet and D. Suleiman “Sulfonation and Characterization of Poly...the 2015 ACS PRISM Meeting San Juan , PR March, 2015. 3. D. Suleiman “Polymer Nanocomposites: Technology for the XXI Century.” Oral Key Note...have been using the equipment: 1. Rinaldo Díaz 2. Arnaldo López 3. Alexander Millet 4. Nataira Pagán 5. Luis Sotomayor 6. Vanessa Torres 7

Dielectric Properties of Polymer Matrix Composites Prepared from Conductive Polymer Treated Fabrics

DTIC Science & Technology

1992-02-01

JPS 09827 finish. The doping agent used was anthraquinone-2 sulfonic acid. (3) A 5 x 5 S2-glass 24 oz. woven roving with an Owens Corning 463 finish...x- I S2-glass 27 oz. woven roving with an Owens Corning 933 finish, nominally equiv- alent to the JPS 09827 finish. The doping agent used was...were fabricated by laminating the layers of Fabric with wet polyester resin ( Owens Corning E-780) and subsequently processing the com- posites using the

Investigation of Proton Conductivity of Cation-Exchanged, Sulfonated Poly(b-Styrene-b-Isobutylene-b-Styrene) Membranes

DTIC Science & Technology

2009-09-01

solvents. Similar behavior was observed for Nafion -117 (also a polymer with ionic SO3H clusters) by other researchers (14). Results shown in this...pattern was only valid for ionic S-SIBS membranes exchanged with cations; neither acid form of SIBS-97-H nor Nafion -117 fell on this line. In order...10  vi INTENTIONALLY LEFT BLANK. 1 1. Introduction Research in ionic polymers has been gaining popularity in the scientific community

High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study.

PubMed

Diamanti, Eleftheria; Gregurec, Danijela; Rodríguez-Presa, María José; Gervasi, Claudio A; Azzaroni, Omar; Moya, Sergio E

2016-06-28

Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 10(7) Ω cm(2), which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance.

Coordination polymer nanocapsules prepared using metal-organic framework templates for pH-responsive drug delivery

NASA Astrophysics Data System (ADS)

Tang, Lei; Shi, Jiafu; Wang, Xiaoli; Zhang, Shaohua; Wu, Hong; Sun, Hongfan; Jiang, Zhongyi

2017-07-01

A facile, efficient, and versatile approach is presented to synthesize pH-responsive nanocapsules (˜120 nm) by combining the advantages of metal-organic frameworks (MOFs) and metal-organic thin films. ZIF-8 nanoparticles are used as templates on which a thin film coating of iron(III)-catechol complexes is derived from the coordination between dopamine-modified alginate (AlgDA) and iron(III) ions. After the template removal, nanocapsules with a pH-responsive wall are obtained. Doxorubicin (Dox), a typical anticancer drug, is first immobilized in ZIF-8 frameworks through coprecipitation and then encapsulated in nanocapsules after the removal of ZIF-8. The structure of the iron(III)-catechol complex varies with pH value, thus conferring the Dox@Nanocapsules with tailored release behavior in vitro. Cytotoxicity tests illustrate the highly effective cytotoxicity of Dox@Nanocapsules towards cancer cells. This study provides a new method for preparing smart nanocapsules and offers more opportunities for the controlled delivery of drugs.

Antibacterial polymer coatings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan

2009-09-01

A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores onmore » its surface.« less

Assessment of relative flammability and thermochemical properties of some thermoplastic materials

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Parker, J. A.

1977-01-01

Thermomechanical properties, flammability, oxygen index, relative toxicity of pyrolysis effluents, and char yields were studied for 12 advanced polymers which are candidates for use in aircraft interiors as decorative films, compression- and injection-molded parts and thermoplastic parts. Polymers sampled included polyphenylene sulfide, 9,9 bis (4-hydroxyphenol) fluorene polycarbonate-poly (dimethylsiloxane), polyether sulfone, polyvinyl fluoride and polyvinylidene fluoride. Availability of these samples, whether in commercial form or in test quantities, is specified. An estimate of relative fire resistance for the materials was obtained; the five polymers listed above were found to be the most fire resistant of the 12 sampled.

Clustering effects in ionic polymers: Molecular dynamics simulations.

PubMed

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S

2015-08-01

Ionic clusters control the structure, dynamics, and transport in soft matter. Incorporating a small fraction of ionizable groups in polymers substantially reduces the mobility of the macromolecules in melts. These ionic groups often associate into random clusters in melts, where the distribution and morphology of the clusters impact the transport in these materials. Here, using molecular dynamic simulations we demonstrate a clear correlation between cluster size and morphology with the polymer mobility in melts of sulfonated polystyrene. We show that in low dielectric media ladderlike clusters that are lower in energy compared with spherical assemblies are formed. Reducing the electrostatic interactions by enhancing the dielectric constant leads to morphological transformation from ladderlike clusters to globular assemblies. Decrease in electrostatic interaction significantly enhances the mobility of the polymer.

Liquid-liquid phase separation in dilute solutions of poly(styrene sulfonate) with multivalent cations: Phase diagrams, chain morphology, and impact of temperature

NASA Astrophysics Data System (ADS)

Hansch, Markus; Hämisch, Benjamin; Schweins, Ralf; Prévost, Sylvain; Huber, Klaus

2018-01-01

The dilute solution behavior of sodium poly(styrene sulfonate) is studied in the presence of trivalent Al3+ and bivalent Ba2+ cations at various levels of excess NaCl. The study evaluates the phase behavior and the morphology of the polyelectrolyte chains with increasing extent of decoration with the Al3+ and Ba2+ cations and analyses the effect of temperature on these decorated chains. The phase behavior is presented in the form of the cation concentration versus the respective poly(styrene sulfonate) concentration, recorded at the onset of precipitation. Whereas poly(styrene sulfonate) with Al3+ exhibits a linear phase boundary, denoted as the "threshold line," which increases with increasing poly(styrene sulfonate) concentration, Ba2+ cations show a threshold line which is independent of the poly(styrene sulfonate) concentration. An additional re-entrant phase, at considerably higher cation content than those of the threshold lines, is observed with Al3+ cations but not with Ba2+ cations. The threshold line and the re-entrant phase boundary form parts of the liquid-liquid phase boundary observed at the limit of low polymer concentration. The dimensions of the polyelectrolyte chains shrink considerably while approaching the respective threshold lines on increase of the Al3+ and Ba2+ cation content. However, subtle differences occur between the morphological transformation induced by Al3+ and Ba2+. Most strikingly, coils decorated with Al3+ respond very differently to temperature variations than coils decorated with Ba2+ do. As the temperature increases, the poly(styrene sulfonate) chains decrease their size in the presence of Al3+ cations but increase in size in the presence of Ba2+ cations.

The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suriguga,; Li, Xiao-Fei; Li, Yang

2013-12-15

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependentmore » increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation.« less

Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Mulijani, S.

2017-01-01

Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

Biochemical synthesis of water soluble conducting polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, Ferdinando F., E-mail: Ferdinando-Bruno@uml.edu; Bernabei, Manuele

2016-05-18

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadaysmore » tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.« less

Synthesis and Characterization of SF-PPV-I

NASA Technical Reports Server (NTRS)

Wang, Y.; Fan, Z.; Taft, C.; Sun, S.

2001-01-01

Conjugated electro-active polymers find their potential applications in developing variety inexpensive and flexible shaped electronic and photonic devices, such as photovoltaic or photo/electro light emitting devices. In many of these opto-electronic polymeric materials, certain electron rich donors and electron deficient acceptors are needed in order to fine-tune the electronic or photonic properties of the desired materials and structures. While many donor type of conjugated polymers have been widely studied and developed in the past decades, there are relatively fewer acceptor type of conjugated polymers have been developed. Key acceptor type conjugated polymers developed so far include C60 and CN-PPV, and each has its limitations. Due to the complexity and diversity of variety future electronic materials and structural needs, alternative and synthetically amenable acceptor conjugated polymers need to be developed. In this paper, we present the synthesis and characterization of a new acceptor conjugated polymer, a sulfone derivatized polyphenylenevinylene "SF-PPV".

Better Proton-Conducting Polymers for Fuel-Cell Membranes

NASA Technical Reports Server (NTRS)

Narayan, Sri; Reddy, Prakash

2012-01-01

Polyoxyphenylene triazole sulfonic acid has been proposed as a basis for development of improved proton-conducting polymeric materials for solid-electrolyte membranes in hydrogen/air fuel cells. Heretofore, the proton-conducting membrane materials of choice have been exemplified by a family of perfluorosulfonic acid-based polymers (Nafion7 or equivalent). These materials are suitable for operation in the temperature of 75 to 85 C, but in order to reduce the sizes and/or increase the energy-conversion efficiencies of fuel-cell systems, it would be desirable to increase temperatures to as high as 120 C for transportation applications, and to as high as 180 C for stationary applications. However, at 120 C and at relative humidity values below 50 percent, the loss of water from perfluorosulfonic acid-based polymer membranes results in fuel-cell power densities too low to be of practical value. Therefore, membrane electrolyte materials that have usefully high proton conductivity in the temperature range of 180 C at low relative humidity and that do not rely on water for proton conduction at 180 C would be desirable. The proposed polyoxyphenylene triazole sulfonic acid-based materials have been conjectured to have these desirable properties. These materials would be free of volatile or mobile acid constituents. The generic molecular structure of these materials is intended to exploit the fact, demonstrated in previous research, that materials that contain ionizable acid and base groups covalently attached to thermally stable polymer backbones exhibit proton conduction even in the anhydrous state.

Chitin nanowhisker-supported sulfonated poly(ether sulfone) proton exchange for fuel cell applications.

PubMed

Zhang, Chan; Zhuang, Xupin; Li, Xiaojie; Wang, Wei; Cheng, Bowen; Kang, Weimin; Cai, Zhanjun; Li, Mengqin

2016-04-20

To balance the relationship among proton conductivity and mechanic strength of sulfonated poly(ether sulfone) (SPES) membrane, chitin nanowhisker-supported nanocomposite membranes were prepared by incorporating whiskers into SPES. The as-prepared chitin whiskers were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation of α-chitin from crab shells. The structure and properties of the composite membranes were examined as proton exchange membrane (PEM). Results showed that chitin nanowhiskers were dispersed incompactly in the SPES matrix. Thermal stability, mechanical properties, water uptake and proton conductivity of the nanocomposite films were improved from those of the pure SPES film with increasing whisker content, which ascribed to strong interactions between whiskers and between SPES molecules and chitin whiskers via hydrogen bonding. These indicated that composition of filler and matrix got good properties and whisker-supported membranes are promising materials for PEM. Copyright © 2015 Elsevier Ltd. All rights reserved.

The relationship between surface tension and the industrial performance of water-soluble polymers prepared from acid hydrolysis lignin, a saccharification by-product from woody materials.

PubMed

Matsushita, Yasuyuki; Imai, Masanori; Iwatsuki, Ayuko; Fukushima, Kazuhiko

2008-05-01

In this study, water-soluble anionic and cationic polymers were prepared from sulfuric acid lignin (SAL), an acid hydrolysis lignin, and the relationship between the surface tension of these polymers and industrial performance was examined. The SAL was phenolized (P-SAL) to enhance its solubility and reactivity. Sulfonation and the Mannich reaction with aminocarboxylic acids produced water-soluble anionic polymers and high-dispersibility gypsum paste. The dispersing efficiency increased as the surface tension decreased, suggesting that the fluidity of the gypsum paste increased with the polymer adsorption on the gypsum particle surface. Water-soluble cationic polymers were prepared using the Mannich reaction with dimethylamine. The cationic polymers showed high sizing efficiency under neutral papermaking conditions; the sizing efficiency increased with the surface tension. This suggests that the polymer with high hydrophilicity spread in the water and readily adhered to the pulp surface and the rosin, showing good retention.

Dynamics and lithium binding energies of polyelectrolytes based on functionalized poly(para-phenylene terephthalamide).

PubMed

Grozema, F C; Best, A S; van Eijck, L; Stride, J; Kearley, G J; de Leeuw, S W; Picken, S J

2005-04-28

Polyelectrolyte materials are an interesting class of electrolytes for use in fuel cell and battery applications. Poly(para-phenylene terephthalamide) (PPTA, Kevlar) is a liquid crystalline polymer that, when sulfonated, is a polyelectrolyte that exhibits moderate ion conductivity at elevated temperatures. In this work, quasi-elastic neutron scattering (QENS) experiments were performed to gain insight into the effect of the presence of lithium counterions on the chain dynamics in the material. It was found that the addition of lithium ions decreases the dynamics of the chains. Additionally, the binding of lithium ions to the sulfonic acids groups was investigated by density functional theory (DFT) calculations. It was found that the local surroundings of the sulfonic acid group have very little effect on the lithium-ion binding energy. Binding energies for a variety of different systems were all calculated to be around 150 kcal/mol. The DFT calculations also show the existence of a structure in which a single lithium ion interacts with two sulfonic acid moieties on different chains. The formation of such "electrostatic cross-links" is believed to be the source of the increased tendency to aggregate and the reduced dynamics in the presence of lithium ions.

High performance polypyrrole coating for corrosion protection and biocidal applications

NASA Astrophysics Data System (ADS)

Nautiyal, Amit; Qiao, Mingyu; Cook, Jonathan Edwin; Zhang, Xinyu; Huang, Tung-Shi

2018-01-01

Polypyrrole (PPy) coating was electrochemically synthesized on carbon steel using sulfonic acids as dopants: p-toluene sulfonic acid (p-TSA), sulfuric acid (SA), (±) camphor sulfonic acid (CSA), sodium dodecyl sulfate (SDS), and sodium dodecylbenzene sulfonate (SDBS). The effect of acidic dopants (p-TSA, SA, CSA) on passivation of carbon steel was investigated by linear potentiodynamic and compared with morphology and corrosion protection performance of the coating produced. The types of the dopants used were significantly affecting the protection efficiency of the coating against chloride ion attack on the metal surface. The corrosion performance depends on size and alignment of dopant in the polymer backbone. Both p-TSA and SDBS have extra benzene ring that stack together to form a lamellar sheet like barrier to chloride ions thus making them appropriate dopants for PPy coating in suppressing the corrosion at significant level. Further, adhesion performance was enhanced by adding long chain carboxylic acid (decanoic acid) directly in the monomer solution. In addition, PPy coating doped with SDBS displayed excellent biocidal abilities against Staphylococcus aureus. The polypyrrole coatings on carbon steels with dual function of anti-corrosion and excellent biocidal properties shows great potential application in the industry for anti-corrosion/antimicrobial purposes.

Resistive and Capacitive γ-Ray Dosimeters Based On Triggered Depolymerization in Carbon Nanotube Composites.

PubMed

Zeininger, Lukas; He, Maggie; Hobson, Stephen T; Swager, Timothy M

2018-05-25

We report γ-ray dosimeters using carbon nanotubes wrapped with metastable poly(olefin sulfone)s (POSs) that readily depolymerize when exposed to ionizing radiation. New POSs, designed for wrapping single-walled carbon nanotubes (SWCNTs), are synthesized and characterized. The resulting POS-SWCNT composites serve as the active transducer in a novel class of γ-ray dosimeters. In our devices, polymer degradation results in immediate changes in the electronic potential of the POS-SWCNT active layers by decreasing the electron tunneling barriers between individualized tubes and by creating enhanced cofacial π-π electron contacts. By incorporating the SWCNT-POS composites into small resistive device platforms, we establish a rare example of real-time detection and dosimetry of radioactive ionizing radiation using organic-based materials. We show that the sensitivity of our platform closely depends on the intrinsic stability of the polymer matrix, the opacity toward γ-rays, and the dispersion efficiency (i.e., the individualization and isolation of the individual SWCNT charge carriers). Resistance decreases up to 65% after irradiation with a 40 krad dose demonstrates the high sensitivity of this novel class of γ-ray sensors. In addition, the detection mechanism was evaluated using a commercial capacitive device platform. The ease of fabrication and low power consumption of these small and inexpensive sensor platforms combined with appealing sensitivity parameters establishes the potential of the poly(olefin sulfone)-SWCNT composites to serve as a new transduction material in γ-ray sensor applications.

Polyaryl ethers and related polysiloxane copolymer molecular coatings preparation and radiation degrdation

NASA Technical Reports Server (NTRS)

Mcgrath, J. E.; Hedrick, J. L.; Webster, D. C.; Johnson, B. C.; Mohanty, D. K.; Yilgor, I.

1983-01-01

Poly(arylene ether sulfones) comprise a class of materials known as engineering thermoplastics which have a variety of important applications. These polymers are tough, rigid materials with good mechanical properties over a wide temperature range, and they are processed by conventional methods into products typically having excellent hydrolytic, thermal, oxidative and dimensional stability. Wholly aromatic random copolymers of hydroquinone and biphenol with 4.4 prime dichlorodiphenyl sulfone were synthesized via mechanical nucleophilic displacement. Their structures were characterized and mechanical behavior studied. These tough, ductile copolymers show excellent radiation resistance to electron beam treatment and retain much of the mechanical properties up to at least 700 Mrads under argon.

Space radiation-induced effects in polymer photodetectors

NASA Astrophysics Data System (ADS)

Taylor, Edward W.; Le, Dang T.; Durstock, Michael F.; Taylor, Barney E.; Claus, Richard O.; Zeng, Tingying; Morath, Christian P.; Cardimona, David A.

2002-09-01

Self-assembled polymer photo-detectors (PPDs) composed of ruthenium complex N3 and PPDs based on thin films of poly(p-phenylene vinlyene) with sulfonated polystyrene are examined for their ability to function in a simulated space radiation environment. Examination of the PPD pre- and post- response data following gamma-ray irradiation ranging in total dose from 10 krad(Si) to 100 krad(Si) are examined. The output photovoltage was observed to decrease for all irradiated devices. The brief study was performed at room temperature and a discussion of the preliminary data and results are presented.

Improved detergent-based recovery of polyhydroxyalkanoates (PHAs).

PubMed

Yang, Yung-Hun; Brigham, Christopher; Willis, Laura; Rha, ChoKyun; Sinskey, Anthony

2011-05-01

Extracting polyhydroxyalkanoate (PHA) polymer from bacterial cells often involves harsh conditions, including use of environmentally harmful solvents. We evaluated different detergents under various conditions to extract PHA from Ralstonia eutropha and Escherichia coli cells. Most detergents tested recovered highly pure PHA polymer from cells in amounts that depended on the percentage of polymer present in the cell. Detergents such as linear alkylbenzene sulfonic acid (LAS-99) produced a high yield of high purity polymer, and less detergent was needed compared to the amount of SDS to produce comparable yields. LAS-99 also has the advantage of being biodegradable and environmentally safe. Chemical extraction of PHA with detergents could potentially minimize or eliminate the need to use harsh organic solvents, thus making industrial PHA production a cleaner technology process. © Springer Science+Business Media B.V. 2011

Clustering effects in ionic polymers: Molecular dynamics simulations

DOE PAGES

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S.

2015-08-18

Ionic clusters control the structure, dynamics, and transport in soft matter. Incorporating a small fraction of ionizable groups in polymers substantially reduces the mobility of the macromolecules in melts. Furthermore, these ionic groups often associate into random clusters in melts, where the distribution and morphology of the clusters impact the transport in these materials. Here, using molecular dynamic simulations we demonstrate a clear correlation between cluster size and morphology with the polymer mobility in melts of sulfonated polystyrene. We show that in low dielectric media ladderlike clusters that are lower in energy compared with spherical assemblies are formed. Reducing themore » electrostatic interactions by enhancing the dielectric constant leads to morphological transformation from ladderlike clusters to globular assemblies. Finally, decrease in electrostatic interaction significantly enhances the mobility of the polymer.« less

The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells.

PubMed

Suriguga; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

2013-12-15

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. © 2013.

Influence of grafting solvents on the properties of polymer electrolyte membranes prepared by γ-ray preirradiation method

NASA Astrophysics Data System (ADS)

Kimura, Yosuke; Asano, Masaharu; Chen, Jinhua; Maekawa, Yasunari; Katakai, Ryoichi; Yoshida, Masaru

2008-07-01

The effect of grafting solvents, such as isopropanol (iPrOH), tetrachloroethane (TCE), tetrahydrofuran (THF), and toluene, on the preparation of poly(ethylene- co-tetrafluoroethylene)-graft-poly(styrene sulfonic acid) (ETFE-g-PSSA) electrolyte membranes by the γ-ray preirradiation grafting method was investigated. It was found that the iPrOH can drastically accelerate the grafting, resulting in a higher degree of grafting. However, for an appropriate degree of grafting of about 50%, the sulfonic acid groups in the ETFE-g-PSSA membrane prepared with the iPrOH were mainly distributed near the membrane surface, as shown by low proton conductivity in the membrane thickness direction. In contrast to this result, the ETFE-g-PSSA membranes prepared with the THF, toluene and TCE exhibited uniform distribution of the sulfonic acid groups in the membrane. Especially, in the case of the TCE grafting solvent, the chemical stability of the resultant electrolyte membrane was clearly higher than those prepared with the other grafting solvents.

Cross-linked sulfonated poly(ether ether ketone) by using diamino-organosilicon for proton exchange fuel cells.

PubMed

Kayser, Marie J; Reinholdt, Marc X; Kaliaguine, Serge

2011-03-31

Fuel cells are at the battlefront to find alternate sources of energy to the highly polluting, economically and environmentally constraining fossil fuels. This work uses an organosilicon molecule presenting two amine functions, bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS) with the aim of preparing cross-linked sulfonated poly(ether ether ketone) (SPEEK) based membranes. The hybrid membranes obtained at varying APTMDS loadings are characterized for their acid, proton conductivity, water uptake, and swelling properties. APTMDS may be considered as an extreme case of silica nanoparticle and is therefore most advantageously distributed within the polymeric matrix. The two amine groups can interact, via electrostatic interactions, with the sulfonic acid groups of SPEEK, resulting in a double anchoring of the molecule. The addition of a small amount of APTMDS is enhancing the mechanical and hydrolytic properties of the membranes and allows some unfolding of the polymer chains, rendering some acid sites accessible to water molecules and thus available for proton transport.

Protein-based underwater adhesives and the prospects for their biotechnological production.

PubMed

Stewart, Russell J

2011-01-01

Biotechnological approaches to practical production of biological protein-based adhesives have had limited success over the last several decades. Broader efforts to produce recombinant adhesive proteins may have been limited by early disappointments. More recent synthetic polymer approaches have successfully replicated some aspects of natural underwater adhesives. For example, synthetic polymers, inspired by mussels, containing the catecholic functional group of 3,4-L-dihydroxyphenylalanine adhere strongly to wet metal oxide surfaces. Synthetic complex coacervates inspired by the Sandcastle worm are water-borne adhesives that can be delivered underwater without dispersing. Synthetic approaches offer several advantages, including versatile chemistries and scalable production. In the future, more sophisticated mimetic adhesives may combine synthetic copolymers with recombinant or agriculture-derived proteins to better replicate the structural and functional organization of natural adhesives.

Protein-based underwater adhesives and the prospects for their biotechnological production

PubMed Central

Stewart, Russell J.

2011-01-01

Biotechnological approaches to practical production of biological protein-based adhesives have had limited success over the last several decades. Broader efforts to produce recombinant adhesive proteins may have been limited by early disappointments. More recent synthetic polymer approaches have successfully replicated some aspects of natural underwater adhesives. For example, synthetic polymers, inspired by mussels, containing the catecholic functional group of 3,4-L-dihydroxyphenylalanine adhere strongly to wet metal oxide surfaces. Synthetic complex coacervates inspired by the Sandcastle worm are water-borne adhesives that can be delivered underwater without dispersing. Synthetic approaches offer several advantages, including versatile chemistries and scalable production. In the future, more sophisticated mimetic adhesives may combine synthetic copolymers with recombinant or agriculture-derived proteins to better replicate the structural and functional organization of natural adhesives. PMID:20890598

Sulfonated poly(ether ether ketone)/polypyrrole core-shell nanofibers: a novel polymeric adsorbent/conducting polymer nanostructures for ultrasensitive gas sensors.

PubMed

Wang, Wei; Li, Zhenyu; Jiang, Tingting; Zhao, Zhiwei; Li, Ye; Wang, Zhaojie; Wang, Ce

2012-11-01

Conducting polymers-based gas sensors have attracted increasing research attention these years. The introduction of inorganic sensitizers (noble metals or inorganic semiconductors) within the conducting polymers-based gas sensors has been regarded as the generally effective route for further enhanced sensors. Here we demonstrate a novel route for highly-efficient conducting polymers-based gas sensors by introduction of polymeric sensitizers (polymeric adsorbent) within the conducting polymeric nanostructures to form one-dimensional polymeric adsorbent/conducting polymer core-shell nanocomposites, via electrospinning and solution-phase polymerization. The adsorption effect of the SPEEK toward NH₃ can facilitate the mass diffusion of NH₃ through the PPy layers, resulting in the enhanced sensing signals. On the basis of the SPEEK/PPy nanofibers, the sensors exhibit large gas responses, even when exposed to very low concentration of NH₃ (20 ppb) at room temperature.

Stretchable Light-Emitting Diodes with Organometal-Halide-Perovskite-Polymer Composite Emitters.

PubMed

Bade, Sri Ganesh R; Shan, Xin; Hoang, Phong Tran; Li, Junqiang; Geske, Thomas; Cai, Le; Pei, Qibing; Wang, Chuan; Yu, Zhibin

2017-06-01

Intrinsically stretchable light-emitting diodes (LEDs) are demonstrated using organometal-halide-perovskite/polymer composite emitters. The polymer matrix serves as a microscale elastic connector for the rigid and brittle perovskite and induces stretchability to the composite emissive layers. The stretchable LEDs consist of poly(ethylene oxide)-modified poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as a transparent and stretchable anode, a perovskite/polymer composite emissive layer, and eutectic indium-gallium as the cathode. The devices exhibit a turn-on voltage of 2.4 V, and a maximum luminance intensity of 15 960 cd m -2 at 8.5 V. Such performance far exceeds all reported intrinsically stretchable LEDs based on electroluminescent polymers. The stretchable perovskite LEDs are mechanically robust and can be reversibly stretched up to 40% strain for 100 cycles without failure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Property Enhancement Effects of Side-Chain-Type Naphthalene-Based Sulfonated Poly(arylene ether ketone) on Nafion Composite Membranes for Direct Methanol Fuel Cells.

PubMed

Wang, Baolong; Hong, Lihua; Li, Yunfeng; Zhao, Liang; Zhao, Chengji; Na, Hui

2017-09-20

Nafion/SNPAEK-x composite membranes were prepared by blending raw Nafion and synthesized side-chain-type naphthalene-based sulfonated poly(arylene ether ketone) with a sulfonation degree of 1.35 (SNPAEK-1.35). The incorporation of SNPAEK-1.35 polymer with ion exchange capacity (IEC) of 2.01 mequiv·g -1 into a Nafion matrix has the property enhancement effects, such as increasing IECs, improving proton conductivity, enhancing mechanical properties, reducing methanol crossover, and improving single cell performance of Nafion. Morphology studies show that Nafion/SNPAEK-x composite membranes exhibit a well-defined microphase separation structure depending on the contents of SNPAEK-1.35 polymer. Among them, Nafion/SNPAEK-7.5% with a bicontinuous morphology exhibits the best comprehensive properties. For example, it shows the highest proton conductivities of 0.092 S cm -1 at 25 °C and 0.163 S cm -1 at 80 °C, which are higher than those of recast Nafion with 0.073 S cm -1 at 25 °C and 0.133 S cm -1 at 80 °C, respectively. Nafion/SNPAEK-5.0% and Nafion/SNPAEK-7.5% membranes display an open circuit voltage of 0.77 V and a maximum power density of 47 mW cm -2 at 80 °C, which are much higher than those of recast Nafion of 0.63 V and 24 mW cm -2 under the same conditions. Nafion/SNPAEK-5.0% membrane also has comparable tensile strength (12.7 MPa) to recast Nafion (13.7 MPa), and higher Young's modulus (330 MPa) than that of recast Nafion (240 MPa). By combining their high proton conductivities, comparable mechanical properties, and good single cell performance, Nafion/SNPAEK-x composite membranes have the potential to be polymer electrolyte materials for direct methanol fuel cell applications.

Induction of uterine adenocarcinoma in CD-1 mice by catechol estrogens.

PubMed

Newbold, R R; Liehr, J G

2000-01-15

Catechol estrogens may mediate estrogen-induced carcinogenesis because 4-hydroxyestradiol induces DNA damage and renal tumors in hamsters, and this metabolite is formed in the kidney and estrogen target tissues by a specific estrogen 4-hydroxylase. We examined the carcinogenic potential of catechol estrogen in an experimental model previously reported to result in a high incidence of uterine adenocarcinoma after neonatal exposure to diethylstilbestrol. Outbred female CD-1 mice were treated with 2- or 4-hydroxyestradiol, 17beta-estradiol, or 17alpha-ethinyl estradiol on days 1-5 of neonatal life (2 microg/pup/day) and sacrificed at 12 or 18 months of age. Mice treated with 17beta-estradiol or 17a-ethinyl estradiol had a total uterine tumor incidence of 7% or 43%, respectively. 2-Hydroxyestradiol induced tumors in 12% of the mice, but 4-hydroxyestradiol was the most carcinogenic estrogen, with a 66% incidence of uterine adenocarcinoma. Both 2- and 4-hydroxylated catechols were estrogenic and increased uterine wet weights in these neonates. These data demonstrate that both 2- and 4-hydroxyestradiol are carcinogenic metabolites. The high tumor incidence induced by 4-hydroxyestradiol supports the postulated role of this metabolite in hormone-associated cancers.

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix

NASA Astrophysics Data System (ADS)

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

2014-06-01

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 μM and a linear detection range from 0.39 μM to 8.98 μM for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 μM. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

PubMed

Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

2014-12-01

Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mineralization of polycyclic aromatic hydrocarbons by the white rot fungus Pleurotus ostreatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezalel, L.; Hadar, Y.; Cerniglia, C.E.

White rot fungi, including Pleurotus ostreatus, have the ability to efficiently degrade lignin, a naturally occurring aromatic polymer. Previous work has found these organisms were able to degrade PAHs and in some cases to mineralize them; most of the work was done with Phanerochaete chrysosporium. P. ostreatus differs from P. chrysosporium in its lignin degradation mechanism. In this study, enzymatic activities were monitored during P. ostreatus growth in the presence of PAHs and the fungus`s ability to mineralize catechol and various PAHs was demonstrated. 29 refs., 3 figs., 1 tab.

Coupling and Reactions of 5-Hydroxyconiferyl Alcohol in Lignin Formation.

PubMed

Elder, Thomas; Berstis, Laura; Beckham, Gregg T; Crowley, Michael F

2016-06-15

The catechol alcohols, caffeyl and 5-hydroxyconiferyl alcohol, may be incorporated into lignin either naturally or through genetic manipulation. Due to the presence of o-OH groups, these compounds form benzodioxanes, a departure from the interunit connections found in lignins derived from the cinnamyl alcohols. In nature, lignins composed of caffeyl and 5-hydroxyconiferyl alcohol are linear homopolymers and, as such, may have properties that make them amenable for use in value-added products, such as lignin-based carbon fibers. In the current work, results from density functional theory calculations for the reactions of 5-hydroxyconiferyl alcohol, taking stereochemistry into account, are reported. Dehydrogenation and quinone methide formation are found to be thermodynamically favored for 5-hydroxyconiferyl alcohol, over coniferyl alcohol. The comparative energetics of the rearomatization reactions suggest that the formation of the benzodioxane linkage is under kinetic control. Ring-opening reactions of the benzodioxane groups show that the bond dissociation enthalpy of the α-O cleavage reaction is lower than that of the β-O reaction. The catechol lignins represent a novel form of the polymer that may offer new opportunities for bioproducts and genetic targets.

Non-aqueous liquid compositions comprising ion exchange polymers

DOEpatents

Kim, Yu Seung; Lee, Kwan-Soo; Rockward, Tommy Q. T.

2013-03-12

Compositions, and methods of making thereof, comprising from about 1% to about 5% of a perfluorinated sulfonic acid ionomer or a hydrocarbon-based ionomer; and from about 95% to about 99% of a solvent, said solvent consisting essentially of a polyol; wherein said composition is substantially free of water and wherein said ionomer is uniformly dispersed in said solvent.

Non-aqueous liquid compositions comprising ion exchange polymers

DOEpatents

Kim, Yu Seung [Los Alamos, NM; Lee, Kwan-Soo [Blacksburg, VA; Rockward, Tommy Q. T. [Rio Rancho, NM

2011-07-19

Compositions, and methods of making thereof, comprising from about 1% to about 5% of a perfluorinated sulfonic acid ionomer or a hydrocarbon-based ionomer; and from about 95% to about 99% of a solvent, said solvent consisting essentially of a polyol; wherein said composition is substantially free of water and wherein said ionomer is uniformly dispersed in said solvent.

Methods for removing contaminant matter from a porous material

DOEpatents

Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

2010-11-16

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Systems and strippable coatings for decontaminating structures that include porous material

DOEpatents

Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

2011-12-06

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Determination of the Si-conducting polymer interfacial properties using A-C impedance techniques

NASA Technical Reports Server (NTRS)

Nagasubramanian, G.; Di Stefano, Salvador; Moacanin, Jovan

1985-01-01

A study was made of the interfacial properties of poly(pyrrole) (PP) deposited electrochemically onto single crystal p-Si surfaces. The interfacial properties are dependent upon the counterions. The formation of 'quasi-ohmic' and 'nonohmic' contacts, respectively, of PP(ClO4) and PP films doped with other counterions (BF4 and para-toluene sulfonate) with p-Si, are explained in terms of the conductivity of these films and the flat band potential, V(fb), of PP relative to that of p-Si. The PP film seems to passivate or block intrinsic surface states present on the p-Si surface. The differences in the impedance behavior of para-toluene sulfonate doped and ClO4 doped PP are compared.

Water dynamics in rigid ionomer networks.

PubMed

Osti, N C; Etampawala, T N; Shrestha, U M; Aryal, D; Tyagi, M; Diallo, S O; Mamontov, E; Cornelius, C J; Perahia, D

2016-12-14

The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.

Controlled Radical Polymerization as an Enabling Approach for the Next Generation of Protein-Polymer Conjugates.

PubMed

Pelegri-O'Day, Emma M; Maynard, Heather D

2016-09-20

Protein-polymer conjugates are unique constructs that combine the chemical properties of a synthetic polymer chain with the biological properties of a biomacromolecule. This often leads to improved stabilities, solubilities, and in vivo half-lives of the resulting conjugates, and expands the range of applications for the proteins. However, early chemical methods for protein-polymer conjugation often required multiple polymer modifications, which were tedious and low yielding. To solve these issues, work in our laboratory has focused on the development of controlled radical polymerization (CRP) techniques to improve synthesis of protein-polymer conjugates. Initial efforts focused on the one-step syntheses of protein-reactive polymers through the use of functionalized initiators and chain transfer agents. A variety of functional groups such as maleimide and pyridyl disulfide could be installed with high end-group retention, which could then react with protein functional groups through mild and biocompatible chemistries. While this grafting to method represented a significant advance in conjugation technique, purification and steric hindrance between large biomacromolecules and polymer chains often led to low conjugation yields. Therefore, a grafting from approach was developed, wherein a polymer chain is grown from an initiating site on a functionalized protein. These conjugates have demonstrated improved homogeneity, characterization, and easier purification, while maintaining protein activity. Much of this early work utilizing CRP techniques focused on polymers made up of biocompatible but nonfunctional monomer units, often containing oligoethylene glycol meth(acrylate) or N-isopropylacrylamide. These branched polymers have significant advantages compared to the historically used linear poly(ethylene glycols) including decreased viscosities and thermally responsive behavior, respectively. Recently, we were motivated to use CRP techniques to develop polymers with rationally designed and functional biological properties for conjugate preparation. Specifically, two families of saccharide-inspired polymers were developed for stabilization and activation of therapeutic biomolecules. A series of polymers with trehalose side-chains and vinyl backbones were prepared and used to stabilize proteins against heat and lyophilization stress as both conjugates and additives. These materials, which combine properties of osmolytes with nonionic surfactants, have significant potential for in vivo therapeutic use. Additionally, polymers that mimic the structure of the naturally occurring polysaccharide heparin were prepared. These polymers contained negatively charged sulfonate groups and imparted stabilization to a heparin-binding growth factor after conjugation. A screen of other sulfonated polymers led to the development of a polymer with improved heparin mimesis, enhancing both stability and activity of the protein to which it was attached. Chemical improvements over the past decade have enabled the preparation of a diverse set of protein-polymer conjugates by controlled polymerization techniques. Now, the field should thoroughly explore and expand both the range of polymer structures and also the applications available to protein-polymer conjugates. As we move beyond medicine toward broader applications, increased collaboration and interdisciplinary work will result in the further development of this exciting field.

Synthesis and characterization of ionomers as polymer electrolytes for energy conversion devices

NASA Astrophysics Data System (ADS)

Oh, Hyukkeun

Single-ion conducting electrolytes present a unique alternative to traditional binary salt conductors used in lithium-ion batteries. Secondary lithium batteries are considered as one of the leading candidates to replace the combustible engines in automotive technology, however several roadblocks are present which prevent their widespread commercialization. Power density, energy density and safety properties must be improved in order to enable the current secondary lithium battery technology to compete with existing energy technologies. It has been shown theoretically that single-ion electrolytes can eliminate the salt concentration gradient and polarization loss in the cell that develops in a binary salt system, resulting in substantial improvements in materials utilization for high power and energy densities. While attempts to utilize single-ion conducting electrolytes in lithium-ion battery systems have been made, the low ionic conductivities prevented the successful operation of the battery cells in ambient conditions. This work focuses on designing single-ion conducting electrolytes with high ionic conductivities and electrochemical and mechanical stability which enables the stable charge-discharge performance of battery cells. Perfluorosulfonate ionomers are known to possess exceptionally high ionic conductivities due to the electron-withdrawing effect caused by the C-F bonds which stabilizes the negative charge of the anion, leading to a large number of free mobile cations. The effect of perfluorinated sulfonic acid side chains on transport properties of proton exchange membrane polymers was examinated via a comparison of three ionomers, having different side chain structures and a similar polymer backbone. The three different side chain structures were aryl-, pefluoro alkyl-, and alkyl-sulfonic acid groups, respectively. All ionomers were synthesized and characterized by 1H and 19F NMR. A novel ionomer synthesized with a pendant perfluorinated sulfonic acid group and a poly(ether ether ketone) backbone showed the highest proton conductivity and proton diffusion coefficient among the three ionomers, demonstrating the effect of the perfluorinated side chains. The proton conductivity of the novel ionomer was comparable to that of Nafion over a wide humidity range and temperature. A lithium perfluorosulfonate ionomer based on aromatic poly(arylene ether)s with pendant lithium perfluoroethyl sulfonates was prepared by ion exchange of the perlfuorosulfonic acid ionomer, and subsequently incoroporated into a lithium-ion battery cell as a single-ion conducting electrolyte. The microporous polymer film saturated with organic carbonates exhibited a nearly unity Li + transfer number, high ionic conductivity (e.g. > 10-3 S m-1 at room temperature) over a wide range of temperatures, high electrochemical stability, and excellent mechanical properties. Excellent cyclability with almost identical charge and discharge capacities have been demonstrated at ambient temperature in the batteries assembled from the prepared single-ion conductors. The mechanical stability of the polymer film was attributed to the rigid polymer backbone which was largely unaffected by the presence of plasticizing organic solvents, while the porous channels with high concentration of the perfluorinated side chains resulted in high ionic conductivity. The expected high charge-rate performance was not achieved, however, due to the high interfacial impedance present between the polymer electrolyte and the electrodes. Several procedural modifications were employed in order to decrease the interfacial impedance of the battery cell. The poly(arylene ether) based ionomer was saturated with an ionic liquid mixture, in order to explore the possibility of its application as a safe, inflammable electrolyte. A low-viscosity ionic liquid with high ionic conductivity, 1-butyl-3-methylimidazolium thiocyanate which has never been successfully utilized as an electrolyte for lithium-ion batteries was incorporated into a battery cell as a solvent mixture with propylene carbonate and lithium bis(trifluoromethane)sulfonimide impregnated in a free-standing hybrid electrolyte film. Outstanding ionic conductivity was achieved and the lithium half cell comprising a LTO cathode and a lithium metal anode separated by the solid polymer electrolyte showed good cyclability at room temperature and even at 0°C. The presence of a sufficient amount of propylene carbonate, which resulted in flammability of the polymer electrolyte, was discovered to be critical in the electrochemical stability of the polymer electrolyte.

Evaluation of an injectable polymeric delivery system for controlled and localized release of biological factors to promote therapeutic angiogenesis

NASA Astrophysics Data System (ADS)

Rocker, Adam John

Cardiovascular disease remains as the leading cause of death worldwide and is frequently associated with partial or full occlusion of coronary arteries. Currently, angioplasty and bypass surgery are the standard approaches for treating patients with these ischemic heart conditions. However, a large number of patients cannot undergo these procedures. Therapeutic angiogenesis provides a minimally invasive tool for treating cardiovascular diseases by inducing new blood vessel growth from the existing vasculature. Angiogenic growth factors can be delivered locally through gene, cell, and protein therapy. Natural and synthetic polymer growth factor delivery systems are under extensive investigation due their widespread applications and promising therapeutic potential. Although biocompatible, natural polymers often suffer from batch-to-batch variability which can cause unpredictable growth factor release rates. Synthetic polymers offer advantages for growth factor delivery as they can be easily modified to control release kinetics. During the angiogenesis process, vascular endothelial growth factor (VEGF) is necessary to initiate neovessel formation while platelet-derived growth factor (PDGF) is needed later to help stabilize and mature new vessels. In the setting of myocardial infarction, additional anti-inflammatory cytokines like IL-10 are needed to help optimize cardiac repair and limit the damaging effects of inflammation following infarction. To meet these angiogenic and anti-inflammatory needs, an injectable polymer delivery system created from a sulfonated reverse thermal gel encapsulating micelle nanoparticles was designed and evaluated. The sulfonate groups on the thermal gel electrostatically bind to VEGF which controls its release rate, while the micelles are loaded with PDGF and are slowly released as the gel degrades. IL-10 was loaded into the system as well and diffused from the gel over time. An in vitro release study was performed which demonstrated the sequential release capabilities of the polymer system. The ability of the polymer system to induce new blood vessel formation was analyzed in vivo using a subcutaneous injection mouse model. Histological assessment was used to quantify blood vessel formation and an inflammatory response which showed that the polymer delivery system demonstrated a significant increase in functional and mature vessel formation while significantly reducing inflammation.

Preparation of a collagen/polymer hybrid gel designed for tissue membranes. Part I: controlling the polymer-collagen cross-linking process using an ethanol/water co-solvent.

PubMed

Nam, Kwangwoo; Kimura, Tsuyoshi; Funamoto, Seiichi; Kishida, Akio

2010-02-01

The drawback with collagen/2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hybrid gels (collagen/phospholipid polymer hybrid gels) prepared in alkaline morpholinoethane sulfonic acid (MES) aqueous solution is that the cross-linking rate between the polymer and the collagen is low. To solve this problem, ethanol has been adopted as the reaction solvent, to prevent 1-ethyl-3-(3-dimethylaminopropyl)-1-carbodiimide hydrochloride (EDC) hydrolysis. Alterations in the ethanol mole concentration changed the cross-linking rate between the MPC polymer and the collagen gel. Prevention of EDC hydrolysis is clearly observed; protonation of carboxyl groups implies that the ratio of ethanol to water should be controlled. The polymer shows signs of penetration into the collagen gel layer, thus forming a totally homogeneous phase gel. This affects the mechanical strength of the collagen gel, making the gel much stiffer and brittle with an increase in the swelling ratio, as compared with that prepared in MES buffer. However, it is possible to obtain a collagen/phospholipid polymer hybrid gel with a high polymer portion and the cross-linking rate can be successfully controlled.

Chitosan-silica complex membranes from sulfonic acid functionalized silica nanoparticles for pervaporation dehydration of ethanol-water solutions.

PubMed

Liu, Ying-Ling; Hsu, Chih-Yuan; Su, Yu-Huei; Lai, Juin-Yih

2005-01-01

Nanosized silica particles with sulfonic acid groups (ST-GPE-S) were utilized as a cross-linker for chitosan to form a chitosan-silica complex membranes, which were applied to pervaporation dehydration of ethanol-water solutions. ST-GPE-S was obtained from reacting nanoscale silica particles with glycidyl phenyl ether, and subsequent sulfonation onto the attached phenyl groups. The chemical structure of the functionalized silica was characterized with FTIR, (1)H NMR, and energy-dispersive X-ray. Homogeneous dispersion of the silica particles in chitosan was observed with electronic microscopies, and the membranes obtained were considered as nanocomposites. The silica nanoparticles in the membranes served as spacers for polymer chains to provide extra space for water permeation, so as to bring high permeation rates to the complex membranes. With addition of 5 parts per hundred of functionalized silica into chitosan, the resulting membrane exhibited a separation factor of 919 and permeation flux of 410 g/(m(2) h) in pervaporation dehydration of 90 wt % ethanol aqueous solution at 70 degrees C.

Sulfonated polyaniline-based organic electrodes for controlled electrical stimulation of human osteosarcoma cells.

PubMed

Min, Yong; Yang, Yanyin; Poojari, Yadagiri; Liu, Yidong; Wu, Jen-Chieh; Hansford, Derek J; Epstein, Arthur J

2013-06-10

Electrically conducting polymers (CPs) were found to stimulate various cell types such as neurons, osteoblasts, and fibroblasts in both in vitro and in vivo studies. However, to our knowledge, no studies have been reported on the utility of CPs in stimulation of cancer or tumor cells in the literature. Here we report a facile fabrication method of self-doped sulfonated polyaniline (SPAN)-based interdigitated electrodes (IDEs) for controlled electrical stimulation of human osteosarcoma (HOS) cells. Increased degree of sulfonation was found to increase the SPAN conductivity, which in turn improved the cell attachment and cell growth without electrical stimulation. However, an enhanced cell growth was observed under controlled electrical (AC) stimulation at low applied voltage and frequency (≤800 mV and ≤1 kHz). The cell growth reached a maximum threshold at an applied voltage or frequency and beyond which pronounced cell death was observed. We believe that these organic electrodes may find utility in electrical stimulation of cancer or tumor cells for therapy and research and may also provide an alternative to the conventional metal-based electrodes.

Efficient Preparation of Super Antifouling PVDF Ultrafiltration Membrane with One Step Fabricated Zwitterionic Surface.

PubMed

Zhao, Xinzhen; He, Chunju

2015-08-19

On the basis of the excellent fouling resistance of zwitterionic materials, the super antifouling polyvinylidene fluoride (PVDF) membrane was efficiently prepared though one-step sulfonation of PVDF and polyaniline blend membrane in situ. The self-doped sulfonated polyaniline (SPANI) was generated as a novel zwitterionic polymer to improve the antifouling property of PVDF ultrafiltration membrane used in sewage treatment. Surface attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface zeta potential, and water contact angle demonstrated the successful fabrication of zwitterionic interface by convenient sulfonation modification. The static adsorption fouling test showed the quantified adsorption mass of bovine serum albumin (BSA) pollutant on the PVDF/SPANI membrane surface decreases to 3(±2) μg/cm(2), and the water flux recovery ratio (FRR) values were no less than 95% for the three model pollutants of BSA, sodium alginate (SA), and humic acid (HA), which were corresponding hydrophobic, hydrophilic, and natural pollutants in sewage, respectively. This Research Article demonstrated the antifouling advantages of zwitterionic SPANI and aimed to provide a simple method for the large scale preparation of zwitterionic antifouling ultrafiltration membranes.

Fuel cell ion-exchange membrane investigation

NASA Technical Reports Server (NTRS)

Toy, M. S.

1972-01-01

The present deficiencies in the fluorocarbon sulfonic acid membrane used as the solid polymer electrolyte in the H2/O2 fuel cell are studied. Considered are: Adhesives selection, elastomeric formulations, scavenger exploration, and membrane characterization. The significant data are interpreted and recommendations are given for both short and long range further investigations in two of the four major areas: membrane adhesives and membrane stabilization.

Relative size selection of a conjugated polyelectrolyte in virus-like protein structures.

PubMed

Brasch, Melanie; Cornelissen, Jeroen J L M

2012-02-01

A conjugated polyelectrolyte poly[(2-methoxy-5-propyloxy sulfonate)-phenyl-ene vinylene] (MPS-PPV) drives the assembly of virus capsid proteins to form single virus-like particles (VLPs) and aggregates with more than two VLPs, with a relative selection of high molecular weight polymer in the latter. This journal is © The Royal Society of Chemistry 2012

Flocculation of wheat straw soda lignin by hemoglobin and chicken blood: Effects of cationic polymer or calcium chloride

USDA-ARS?s Scientific Manuscript database

Flocculation can be used to separate non-sulfonated lignin from base hydrolyzed biomass. In the industrial process, the lignin is isolated by filtration and washed with water. Some of the lignin is lost in the wash water, and flocculation can be used to recover this lignin. Several ways of enhanc...

Non-aqueous liquid compositions comprising ion exchange polymers reference to related application

DOEpatents

Kim,; Yu Seung, Lee [Los Alamos, NM; Kwan-Soo, Rockward [Los Alamos, NM; T, Tommy Q [Rio Rancho, NM

2012-08-07

Compositions, and methods of making thereof, comprising from about 1% to about 5% of a perfluorinated sulfonic acid ionomer or a hydrocarbon-based ionomer; and from about 95% to about 99% of a solvent, said solvent consisting essentially of a polyol; wherein said composition is substantially free of water and wherein said ionomer is uniformly dispersed in said solvent.

Novel sulfonated polyimide/zwitterionic polymer-functionalized graphene oxide hybrid membranes for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Cao, Li; Kong, Lei; Kong, Lingqian; Zhang, Xingxiang; Shi, Haifeng

2015-12-01

Hybrid membranes (SPI/ZGO) composed of sulfonated polyimide (SPI) and zwitterionic polymer-functionalized graphene oxide (ZGO) are fabricated via a solution-casting method for vanadium redox flow battery (VRB). Successful preparation of ZGO fillers and SPI/ZGO hybrid membranes are demonstrated by FT-IR, XPS and SEM, indicating that ZGO fillers is homogeneously dispersed into SPI matrix. Through controlling the interfacial interaction between SPI matrix and ZGO fillers, the physicochemical properties, e.g., vanadium ion barrier and proton transport pathway, of hybrid membranes are tuned via the zwitterionic acid-base interaction in the hybrid membrane, showing a high ion selectivity and good stability with the incorporated ZGO fillers. SPI/ZGO-4 hybrid membrane proves a higher cell efficiencies (CE: 92-98%, EE: 65-79%) than commercial Nafion 117 membrane (CE: 89-94%, EE: 59-70%) for VRB application at 30-80 mA cm-2. The assembled VRB with SPI/ZGO-4 membrane presents a stable cycling charge-discharge performance over 280 times, which demonstrates its excellent chemical stability under the strong acidic and oxidizing conditions. SPI/ZGO hybrid membranes show a brilliant perspective for VRB application.

Starch derivative-based superabsorbent with integration of water-retaining and controlled-release fertilizers.

PubMed

Zhong, Kang; Lin, Zuan-Tao; Zheng, Xi-Liang; Jiang, Gang-Biao; Fang, Yu-Sheng; Mao, Xiao-Yun; Liao, Zong-Wen

2013-02-15

Phosphate rock (PHR), a traditional fertilizer, is abundant, but is hard to be utilized by plants. To improve the utilization of PHR, and to integrate water-retaining and controlled-release fertilizers, an agricultural superabsorbent polymer based on sulfonated corn starch/poly (acrylic acid) embedding phosphate rock (SCS/PAA/PHR) was prepared. PHR can be suspended and well-dispersed in SCS/PAA by sulfonated corn starch (SCS). PHR and KOH were mixed in acrylic acid solution to provide phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent were investigated. The maximum swelling capacity in distilled water or 0.9 wt.% (weight percent) NaCl solution reached 498 g g(-1) and 65 g g(-1) (water/prepared dry superabsorbent) respectively. Moreover, release behaviours of P and K in SCS/PAA/PHR were also investigated. The results showed that SCS/PAA/PHR possessed excellent sustained-release property of plant nutrient, and the SCS/PAA could improve the P release greatly. Besides, the XPS analysis was employed to study the relationship between PHR and superabsorbent polymer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical and radiation crosslinked polymer electrolyte membranes prepared from radiation-grafted ETFE films for DMFC applications

NASA Astrophysics Data System (ADS)

Chen, Jinhua; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

To develop a highly chemically stable polymer electrolyte membrane for application in a direct methanol fuel cell (DMFC), doubly crosslinked membranes were prepared by chemical crosslinking using bifunctional monomers, such as divinylbenzene (DVB) and bis(p, p-vinyl phenyl) ethane (BVPE), and by radiation crosslinking. The membranes were prepared by grafting of m, p-methylstyrene (MeSt) and p-tert-butylstyrene (tBuSt) into poly(ethylene- co-tetrafluoroethylene) (ETFE) films and subsequent sulfonation. The effects of the DVB and BVPE crosslinkers on the grafting kinetics and the properties of the prepared membranes, such as water uptake, proton conductivity and chemical stability were investigated. Radiation crosslinking was introduced by irradiation of the ETFE base film, the grafted film or the sulfonated membrane. The membrane crosslinked by DVB and BVPE crosslinkers and post-crosslinked by γ-ray irradiation of the corresponding grafted film possessed the highest chemical stability among the prepared membranes, a significantly lower methanol permeability compared to Nafion ® membranes, and a better DMFC performance for high methanol feed concentration. Therefore, this doubly crosslinked membrane was promising for application in a DMFC where relatively high methanol concentration could be fed.

TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes as ultra high power and long life anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Tang, Yakun; Liu, Lang; Wang, Xingchao; Jia, Dianzeng; Xia, Wei; Zhao, Zongbin; Qiu, Jieshan

2016-07-01

TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes have been constructed through the pyrolysis of sulfonated polymer nanotubes and TiO2 hybrids. The TiO2 quantum dots are formed during the pyrolysis, due to the space confinement within the highly cross-linked copolymer networks. The sulfonation degree of the polymer nanotubes is a critical factor to ensure the formation of the unique interpenetrating structure. The nanocomposites exhibit high reversible capacity of 523 mAh g-1 at 100 mA g-1 after 200 cycles, excellent rate capability and superior long-term cycling stability at high current density, which could attain a high discharge capacity of 189 mAh g-1 at 2000 mA g-1 for up to 2000 cycles. The enhanced electrochemical performance of the nanocomposites benefit from the uniform distribution of TiO2 quantum dots, high electronic conductivity of porous carbons and unique interpenetrating structure, which simultaneously solved the major problems of TiO2 anode facing the pulverization, loss of electrical contact and particle aggregation.

Activity and Safety of Synthetic Lectins Based on Benzoboroxole-Functionalized Polymers for Inhibition of HIV Entry

PubMed Central

Mahalingam, Alamelu; Geonnotti, Anthony R.; Balzarini, Jan; Kiser, Patrick F.

2011-01-01

Lectins derived from plant and microbial sources constitute a vital class of entry inhibitors that target the oligomannose residues on the HIV envelope gp120. Despite their potency and specificity, success of lectin-based entry inhibitors may be impeded by issues in regards to economical production, formulation and potential mitogenicity. Therefore, there exists a gap in the HIV therapeutics pipeline that underscores the need for mass producible, synthetic, broad-spectrum, and biocomptabile inhibitors of HIV entry. Here, we present the development of a polymeric synthetic lectin, based on benzoboroxole (BzB), which exhibits weak affinity (~25 M−1) for non-reducing sugars, similar to those found on the HIV envelope. High molecular weight BzB-functionalized polymers demonstrated antiviral activity that increased with an increase in ligand density and molecular weight of the polymer construct; revealing that polyvalency improves activity. Polymers showed significant increase in activity from 25 to 75 mol% BzB functionalization with EC50 of 15 μM and 15 nM, respectively. A further increase in mole functionalization to 90% resulted in an increase of the EC50 (59 ± 5 nM), likely due to the elongated rigid structure of the polymer chain compelled by electrostatic repulsion between the boronic acid groups. An increase in molecular weight of the polymer at 50 mol% BzB functionalization showed a gradual but significant increase in antiviral activity, with the highest activity seen with the 382 kDa polymer (EC50 of 1.1 ± 0.5 nM in CEM cells and 11 ± 3 nM in TZM-bl cells). Supplementing the polymer backbone with 10 mol% sulfonic acid not only increased the aqueous solubility of the polymers by at least 50-fold, but also demonstrated a synergistic increase in anti-HIV activity (4.0 ± 1.5 nM in TZM-bl cells), possibly due to electrostatic interactions between the negatively charged polymer backbone and the positively charged V3-loop in the gp120. The benzoboroxole-sulfonic acid copolymers showed no decrease in activity in the presence of a seminal concentration of fructose (p > 0.05). Additionally, the co-polymers exhibit minimal, if any effect on the cellular viability, barrier properties, or cytokine levels in human reconstructed ecto-cervical tissue after 3 days of repeated exposure and did not show pronounced activity against a variety of other RNA and DNA viruses. PMID:21879735

Reversible clustering of pH- and temperature-responsive Janus magnetic nanoparticles.

PubMed

Isojima, Tatsushi; Lattuada, Marco; Vander Sande, John B; Hatton, T Alan

2008-09-23

Janus nanoparticles have been synthesized consisting of approximately 5 nm magnetite nanoparticles coated on one side with a pH-dependent and temperature-independent polymer (poly(acrylic acid), PAA), and functionalized on the other side by a second (tail) polymer that is either a pH-independent polymer (polystyrene sodium sulfonate, PSSNa) or a temperature-dependent polymer (poly(N-isopropyl acrylamide), PNIPAM). These Janus nanoparticles are dispersed stably as individual particles at high pH values and low temperatures, but can self-assemble at low pH values (PSSNa) or at high temperatures (>31 degrees C) (PNIPAM) to form stable dispersions of clusters of approximately 80-100 nm in hydrodynamic diameter. The Janus nanoparticle compositions were verified using FTIR and XPS, and their structures observed directly by TEM. Their clustering behavior is analyzed by dynamic light scattering and zeta potential measurements.

Gramicidin ion channels in a lipid bilayer supported on polyelectrolyte multilayer films: an electrochemical impedance study.

PubMed

Diamanti, Eleftheria; Gutiérrez-Pineda, Eduart; Politakos, Nikolaos; Andreozzi, Patrizia; Rodriguez-Presa, María José; Knoll, Wolfgang; Azzaroni, Omar; Gervasi, Claudio A; Moya, Sergio E

2017-12-06

Supported membranes on polymer cushions are of fundamental interest as models for cell membranes. The use of polyelectrolyte multilayers (PEMs) assembled by the layer by layer (LbL) technique as supports for a bilayer allows for easy integration of the lipid bilayer on surfaces and devices and for nanoscale tunable spacing of the lipid bilayer. Controlling ionic permeability in lipid bilayers supported on PEMs triggers potential applications in sensing and as models for transport phenomena in cell membranes. Lipid bilayers displaying gramicidin channels are fabricated on top of polyallylamine hydrochloride (PAH) and polystyrene sulfonate (PSS) multilayer films, by the assembly of vesicles of phosphatidylcholine and phosphatidylserine, 50 : 50 M/M, carrying gramicidin (GA). Quartz crystal microbalance with dissipation shows that the vesicles with GA fuse into a bilayer. Atomic force microscopy reveals that the presence of GA alters the bilayer topography resulting in depressions in the bilayer of around 70 nm in diameter. Electrochemical impedance spectroscopy (EIS) studies show that supported bilayers carrying GA have smaller resistances than the bilayers without GA. Lipid layers carrying GA display a higher conductance for K + than for Na + and are blocked in the presence of Ca 2+ .

Antifouling Thin-Film Composite Membranes by Controlled Architecture of Zwitterionic Polymer Brush Layer.

PubMed

Liu, Caihong; Lee, Jongho; Ma, Jun; Elimelech, Menachem

2017-02-21

In this study, we demonstrate a highly antifouling thin-film composite (TFC) membrane by grafting a zwitterionic polymer brush via atom-transfer radical-polymerization (ATRP), a controlled, environmentally benign chemical process. Initiator molecules for polymerization were immobilized on the membrane surface by bioinspired catechol chemistry, leading to the grafting of a dense zwitterionic polymer brush layer. Surface characterization revealed that the modified membrane exhibits reduced surface roughness, enhanced hydrophilicity, and lower surface charge. Chemical force microscopy demonstrated that the modified membrane displayed foulant-membrane interaction forces that were 1 order of magnitude smaller than those of the pristine TFC membrane. The excellent fouling resistance imparted by the zwitterionic brush layer was further demonstrated by significantly reduced adsorption of proteins and bacteria. In addition, forward osmosis fouling experiments with a feed solution containing a mixture of organic foulants (bovine-serum albumin, alginate, and natural organic matter) indicated that the modified membrane exhibited significantly lower water flux decline compared to the pristine TFC membrane. The controlled architecture of the zwitterionic polymer brush via ATRP has the potential for a facile antifouling modification of a wide range of water treatment membranes without compromising intrinsic transport properties.

Epoxidation of 1-Octene with hydrogen peroxide aqueous catalyzed by titania supported sulfonated coal

NASA Astrophysics Data System (ADS)

Nurhadi, Mukhamad

2017-02-01

Titania supported sulfonated coal was created as heterogeneous catalyst for epoxidation of 1-octene with aqueous hydrogen peroxide as oxidant at room temperature. The catalysts were prepared from coal that was sulfonated with H2SO4 (97%) and impregnated 7.2%wt with titanium(IV) isopropoxide (Ti(PrO)4). All catalysts coal (C), CS, Ti(7.2)-CS and Ti(7.2)-CSC were characterized by FTIR. The catalytic performance was tested for epoxidation of 1-octene with H2O2 aqueous as oxidant. It is found that Ti(7.2)-CS possessed the best catalytic performance and it gave the highest 1,2 epoxyoctene 322 µmol.

Electrochromic conductive polymer fuses for hybrid organic/inorganic semiconductor memories

NASA Astrophysics Data System (ADS)

Möller, Sven; Forrest, Stephen R.; Perlov, Craig; Jackson, Warren; Taussig, Carl

2003-12-01

We demonstrate a nonvolatile, write-once-read-many-times (WORM) memory device employing a hybrid organic/inorganic semiconductor architecture consisting of thin film p-i-n silicon diode on a stainless steel substrate integrated in series with a conductive polymer fuse. The nonlinearity of the silicon diodes enables a passive matrix memory architecture, while the conductive polyethylenedioxythiophene:polystyrene sulfonic acid polymer serves as a reliable switch with fuse-like behavior for data storage. The polymer can be switched at ˜2 μs, resulting in a permanent decrease of conductivity of the memory pixel by up to a factor of 103. The switching mechanism is primarily due to a current and thermally dependent redox reaction in the polymer, limited by the double injection of both holes and electrons. The switched device performance does not degrade after many thousand read cycles in ambient at room temperature. Our results suggest that low cost, organic/inorganic WORM memories are feasible for light weight, high density, robust, and fast archival storage applications.

The role of DNA methylation in catechol-enhanced erythroid differentiation of K562 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiao-Fei; Wu, Xiao-Rong; Xue, Ming

2012-11-15

Catechol is one of phenolic metabolites of benzene in vivo. Catechol is also widely used in pharmaceutical and chemical industries. In addition, fruits, vegetables and cigarette smoke also contain catechol. Our precious study showed that several benzene metabolites (phenol, hydroquinone, and 1,2,4-benzenetriol) inhibited erythroid differentiation of K562 cells. In present study, the effect of catechol on erythroid differentiation of K562 cells was investigated. Moreover, to address the role of DNA methylation in catechol-induced effect on erythroid differentiation in K562 cells, methylation levels of erythroid-specific genes were analyzed by Quantitative MassARRAY methylation analysis platform. Benzidine staining showed that exposure to catecholmore » enhanced hemin-induced hemoglobin accumulation in K562 cells in concentration- and time-dependent manners. The mRNA expression of erythroid specific genes, including α-globin, β-globin, γ-globin, erythroid 5-aminolevulinate synthase, erythroid porphobilinogen deaminase, and transcription factor GATA-1 genes, showed a significant concentration-dependent increase in catechol-treated K562 cells. The exposure to catechol caused a decrease in DNA methylation levels at a few CpG sites in some erythroid specific genes including α-globin, β-globin and erythroid porphobilinogen deaminase genes. These results indicated that catechol improved erythroid differentiation potency of K562 cells at least partly via up-regulating transcription of some erythroid related genes, and suggested that inhibition of DNA methylation might be involved in up-regulated expression of some erythroid related genes. -- Highlights: ► Catechol enhanced hemin-induced hemoglobin accumulation. ► Exposure to catechol resulted in up-regulated expression of erythroid genes. ► Catechol reduced methylation levels at some CpG sites in erythroid genes.« less

High cycle life secondary lithium battery

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S. (Inventor); Shen, David H. (Inventor); Carter, Boyd J. (Inventor); Somoano, Robert B. (Inventor)

1985-01-01

A secondary battery (10) of high energy density and long cycle is achieved by coating the separator (18) with a film (21) of cationic polymer such as polyvinyl-imidazoline. The binder of the positive electrode (14) such as an ethylene-propylene elastomer binder (26) containing particles (28) of TiS.sub.2 chalcogenide can also be modified to contain sulfone functional groups by incorporating liquid or solid sulfone materials such as 0.1 to 5 percent by weight of sulfolane into the binder. The negative lithium electrode (14), separator (18) and positive electrode (16) are preferably spirally wound and disposed within a sealed casing (17) containing terminals (32, 34). The modified separator and positive electrode are more wettable by the electrolytes in which a salt is dissolved in a polar solvent such as sulfolane.

Preparation of ionic membranes for zinc/bromine storage batteries

NASA Astrophysics Data System (ADS)

Assink, R. A.; Arnold, C., Jr.

Zinc/bromine flow batteries are being developed for vehicular and utility load leveling applications. During charge, an aqueous zinc bromide salt is electrolyzed to zinc metal and molecular bromine. During discharge, the zinc and bromine react to again form the zinc bromide salt. One serious disadvantage of the microporous separators presently used in the zinc/bromine battery is that modest amounts of bromine and negatively charged bromine moieties permeate through these materials and react with the zinc anode. This results in partial self-discharge of the battery and low coulombic efficiencies. Our approach to this problem is to impregnate the microporous separators with a soluble cationic polyelectrolyte. In laboratory screening tests a sulfonated polysulfone resin and fully fluorinated sulfonic acid polymer substantially reduced bromine permeation with only modest increases in the area resistance.

Ion distribution in quaternary-ammonium-functionalized aromatic polymers: effects on the ionic clustering and conductivity of anion-exchange membranes.

PubMed

Weiber, E Annika; Jannasch, Patric

2014-09-01

A series of copoly(arylene ether sulfone)s that have precisely two, three, or four quaternary ammonium (QA) groups clustered directly on single phenylene rings along the backbone are studied as anion-exchange membranes. The copolymers are synthesized by condensation polymerizations that involve either di-, tri-, or tetramethylhydroquinone followed by virtually complete benzylic bromination using N-bromosuccinimide and quaternization with trimethylamine. This synthetic strategy allows excellent control and systematic variation of the local density and distribution of QA groups along the backbone. Small-angle X-ray scattering of these copolymers shows extensive ionic clustering, promoted by an increasing density of QA on the single phenylene rings. At an ion-exchange capacity (IEC) of 2.1 meq g(-1), the water uptake decreases with the increasing local density of QA groups. Moreover, at moderate IECs at 20 °C, the Br(-) conductivity of the densely functionalized copolymers is higher than a corresponding randomly functionalized polymer, despite the significantly higher water uptake of the latter. Thus, the location of multiple cations on single aromatic rings in the polymers facilitates the formation of a distinct percolating hydrophilic phase domain with a high ionic concentration to promote efficient anion transport, despite probable limitations by reduced ion dissociation. These findings imply a viable strategy to improve the performance of alkaline membrane fuel cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proton exchange membranes for application in fuel cells: grafted silica/SPEEK nanocomposite elaboration and characterization.

PubMed

Reinholdt, Marc X; Kaliaguine, Serge

2010-07-06

Hydrogen technologies and especially fuel cells are key components in the battle to find alternate sources of energy to the highly polluting and economically constraining fossil fuels in an aim to preserve the environment. The present paper shows the synthesis of surface functionalized silica nanoparticles, which are used to prepare grafted silica/SPEEK nanocomposite membranes. The nanoparticles are grafted either with hexadecylsilyl or aminopropyldimethylsilyl moieties or both. The synthesized particles are analyzed using XRD, NMR, TEM, and DLS to collect information on the nature of the particles and the functional groups, on the particle sizes, and on the hydrophilic/hydrophobic character. The composite membranes prepared using the synthesized particles and two SPEEK polymers with sulfonation degrees of 69.4% and 85.0% are characterized for their proton conductivity and water uptake properties. The corresponding curves are very similar for the composites prepared with both polymers and the nanoparticles bearing the two functional groups. The composites prepared with the nanoparticles bearing solely the aminopropyldimethylsilyl moiety exhibit lower conductivity and water uptake, possibly due to higher interaction of the polymer sulfonic acid sites with the amine groups. The composites prepared with the nanoparticles bearing solely the hexadecylsilyl moiety were not further investigated because of very high particles segregation. A study of the proton conductivity as a function of temperature was performed on selected membranes and showed that nanocomposites made with nanoparticles bearing both functional moieties have a higher conductivity at higher temperatures.

Ion exchange materials, method of forming ion exchange materials, and methods of treating liquids

DOEpatents

Wertsching, Alan K.; Peterson, Eric S.; Wey, John E.

2007-12-25

The invention includes an ion affinity material having an organic component which is sulfonated and which is chemically bonded to an inorganic substrate component. The invention includes a method of forming a metal binding material. A solid support material comprising surface oxide groups is provided and an organic component having at least one alkyl halide is covalently linked to at least some of the surface oxide groups to form a modified support material. The at least one alkyl halide is subsequently converted into an alkyl sulfonate. The invention further includes a method and system for extracting ions from a liquid. An ion exchange material having a sulfonated alkyl silane component covalently bonded to a metal oxide support material is provided and a liquid is exposed to the ion exchange material.

Preparation of Proton Exchange Membranes and Lithium Batteries from Melamine-containing Ormosils

NASA Technical Reports Server (NTRS)

Tigelaar, Dean M.; Kinder, James D.; Meador, Mary Ann; Waldecker, James; Bennett, William R.

2004-01-01

Our laboratory has recently reported a series of rodcoil polymers for lithium batteries that display dimensionally stable films with good ionic conductivity. The rod segments consist of rigid linear and branched polyimides and the coil segments are polyethylene oxides (PEO). It has been proposed that good mechanical and transport properties are due to phase separation between the rod and coil segments. It was also observed that increased branching and molecular weight lead to increased conductivity. The following study was undertaken to assess the effects of phase separation in polyalkylene oxides connected by melamine linkages. Melamine was chosen as the linking unit because it provides a branching site, cation binding sites to help ionic transport between polymer chains, and the opportunity for self assembly through hydrogen bonding. Polymers were made by the reaction of cyanuric chloride with a series of amine-terminated alkylene oxides. A linear polymer was first made, followed by reaction of the third site on cyanuric chloride with varying ratios of monofunctional Jeffamine and (3-aminopropyl)triethoxysilane. The lithium trifluoromethane sulfonamide-doped polymers are then crosslinked through a sol-gel process to form free-standing films. Initial results have shown mechanically strong films with lithium conductivities on the order of 2 x 10(exp -5) S/cm at ambient temperature. In a separate study, organically modified silanes (Ormosils) that contain sulfonic acid derivatized melamines have been incorporated into proton exchange membranes. The membranes are made by reaction of the primary amine groups of various ratios of melamine derivative and difunctional Jeffamine (MW = 2000) with the epoxide group of (3-Glycidyloxypropyl)trimethoxysilane. The films were then cross-linked through a sol-gel process. Resulting sulfuric acid doped films are strong, flexible, and have proton conductivities on the order of 2 x l0(exp -2) S/cm (120 C, 25% relative humidity). Our best results have been observed when films contain 60% PEO and 40% sulfonated melamine.

Studies on the effect of dispersoid(ZrO2) in PVdF-co-HFP based gel polymer electrolytes

NASA Astrophysics Data System (ADS)

Sivakumar, M.; Subadevi, R.; Muthupradeepa, R.

2013-06-01

Gel polymer electrolytes containing poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) / Lithium bis(trifluoromethane sulfon)imide (LiTFSI) / mixture of ethylene carbonate and propylene carbonate (EC+PC) with different concendration of ZrO2 has been prepared using the solution casting technique. The conductivity of the prepared electrolyte sample has been determined by AC impedance technique in the range 303-353K. The temperature dependent ionic conductivity plot seems to obey VTF relation. The maximum ionic conductivity value of 4.46 × 10-3S/cm has been obtained for PVdF-co-HFP(32%) - LiTFSI(8%) - EC+PC (60%) + ZrO2(6wt%) based polymer electrolyte. The surface morphology of the prepared electrolyte sample has been studied using SEM.

Composite plasma polymerized sulfonated polystyrene membrane for PEMFC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nath, Bhabesh Kumar; Khan, Aziz; Chutia, Joyanti, E-mail: jchutiaiasst@gmail.com

2015-10-15

Highlights: • Methyl methane sulfonate (MMS) is used as the sulfonating agent. • The proton conductivity of the membrane is found to be 0.141 S cm{sup −1}. • Power density of fuel cell with styrene/MMS membrane is 0.5 W cm{sup −2}. • The membrane exhibits thermal stability up to 140 °C. - Abstract: This work presents the introduction of an organic compound methyl methane sulfonate (MMS) for the first time in fabrication of polystyrene based proton exchange membrane (PEM) by plasma polymerization process. The membrane is fabricated by co-polymerizing styrene and MMS in capacitively coupled continuous RF plasma. The chemicalmore » composition of the plasma polymerized polymer membrane is investigated using Fourier Transform Infrared Spectroscopy which reveals the formation of composite structure of styrene and MMS. The surface morphology studied using AFM and SEM depicts the effect of higher partial pressure of MMS on surface topography of the membrane. The proton transport property of the membrane studied using electrochemical impedance spectroscopy shows the achievement of maximum proton conductivity of 0.141 S cm{sup −1} which is comparable to Nafion 117 membrane. Fuel cell performance test of the synthesized membrane shows a maximum power density of 500 mW cm{sup −2} and current density of 0.62 A cm{sup −2} at 0.6 V.« less

Energetic and electronic computation of the two-hydrogen atom donation process in catecholic and non-catecholic anthocyanidins.

PubMed

Ali, Hussein M; Ali, Isra H

2018-03-15

Antioxidant activity of anthocyanidins is greatly affected by the 3-hydroxyl group and/or a catecholic moiety. The two-hydrogen atom donation process is frequently used to explain the high antioxidant activity of polyphenolic compounds leading to the formation of stable diketones e.g. 1,2-quinones. Thermodynamic parameters, HOMO and spin density were computed to identify the favoured path, either through the 3-hydroxyl group or through the catecholic moiety in a series of catecholic and non-catecholic 3-oxy- (and deoxy)-anthocyanidins. DFT calculations showed that the donation process in non-catecholic anthocyanidins depended on the substituents on ring B. Anthocyanidins with 3',5'-diOMe groups showed donation through 3,4'-OH or, otherwise, through 3,5-OH groups. Catecholic 3-oxyanthocyanidins, on the other hand, showed donation through the 3,4'-OH path rather than the catecholic path (4',3'-path). The 3,4'-path was favoured by the formation of planar 3-radicals in the first step and the stabilization of 4'-radicals in the second step by H-bonding with the 3'-OH group. Copyright © 2017 Elsevier Ltd. All rights reserved.

Magnetite-supported sulfonic acid: a retrievable nanocatalyst for the Ritter reaction and multicomponent reactions

EPA Science Inventory

Magnetite-sulfonic acid (NanocatFe-OSO3H), prepared by wet-impregnation method, serves as a magnetically retrievable sustainable catalyst for the Ritter reaction which can be used in several reaction cycles without any loss of activity.

Activation of the Nrf2 Cell Defense Pathway by Ancient Foods: Disease Prevention by Important Molecules and Microbes Lost from the Modern Western Diet

PubMed Central

Senger, Donald R.; Li, Dan; Jaminet, Shou-Ching; Cao, Shugeng

2016-01-01

The Nrf2 (NFE2L2) cell defense pathway protects against oxidative stress and disorders including cancer and neurodegeneration. Although activated modestly by oxidative stress alone, robust activation of the Nrf2 defense mechanism requires the additional presence of co-factors that facilitate electron exchange. Various molecules exhibit this co-factor function, including sulforaphane from cruciferous vegetables. However, natural co-factors that are potent and widely available from dietary sources have not been identified previously. The objectives of this study were to investigate support of the Nrf2 cell defense pathway by the alkyl catechols: 4-methylcatechol, 4-vinylcatechol, and 4-ethylcatechol. These small electrochemicals are naturally available from numerous sources but have not received attention. Findings reported here illustrate that these compounds are indeed potent co-factors for activation of the Nrf2 pathway both in vitro and in vivo. Each strongly supports expression of Nrf2 target genes in a variety of human cell types; and, in addition, 4-ethylcatechol is orally active in mice. Furthermore, findings reported here identify important and previously unrecognized sources of these compounds, arising from biotransformation of common plant compounds by lactobacilli that express phenolic acid decarboxylase. Thus, for example, Lactobacillus plantarum, Lactobacillus brevis, and Lactobacillus collinoides, which are consumed from a diet rich in traditionally fermented foods and beverages, convert common phenolic acids found in fruits and vegetables to 4-vinylcatechol and/or 4-ethylcatechol. In addition, all of the alkyl catechols are found in wood smoke that was used widely for food preservation. Thus, the potentially numerous sources of alkyl catechols in traditional foods suggest that these co-factors were common in ancient diets. However, with radical changes in food preservation, alkyl catechols have been lost from modern foods. The absence of alkyl catechols from the modern Western diet suggests serious negative consequences for Nrf2 cell defense, resulting in reduced protection against multiple chronic diseases associated with oxidative stress. PMID:26885667

Optimization of a polymer composite employing molecular mechanic simulations and artificial neural networks for a novel intravaginal bioadhesive drug delivery device.

PubMed

Ndesendo, Valence M K; Pillay, Viness; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Buchmann, Eckhart; Meyer, Leith C R; Khan, Riaz A

2012-01-01

This study aimed at elucidating an optimal synergistic polymer composite for achieving a desirable molecular bioadhesivity and Matrix Erosion of a bioactive-loaded Intravaginal Bioadhesive Polymeric Device (IBPD) employing Molecular Mechanic Simulations and Artificial Neural Networks (ANN). Fifteen lead caplet-shaped devices were formulated by direct compression with the model bioactives zidovudine and polystyrene sulfonate. The Matrix Erosion was analyzed in simulated vaginal fluid to assess the critical integrity. Blueprinting the molecular mechanics of bioadhesion between vaginal epithelial glycoprotein (EGP), mucin (MUC) and the IBPD were performed on HyperChem 8.0.8 software (MM+ and AMBER force fields) for the quantification and characterization of correlative molecular interactions during molecular bioadhesion. Results proved that the IBPD bioadhesivity was pivoted on the conformation, orientation, and poly(acrylic acid) (PAA) composition that interacted with EGP and MUC present on the vaginal epithelium due to heterogeneous surface residue distributions (free energy= -46.33 kcalmol(-1)). ANN sensitivity testing as a connectionist model enabled strategic polymer selection for developing an IBPD with an optimally prolonged Matrix Erosion and superior molecular bioadhesivity (ME = 1.21-7.68%; BHN = 2.687-4.981 N/mm(2)). Molecular modeling aptly supported the EGP-MUC-PAA molecular interaction at the vaginal epithelium confirming the role of PAA in bioadhesion of the IBPD once inserted into the posterior fornix of the vagina.

Performance of non-compartmentalized enzymatic biofuel cell based on buckypaper cathode and ferrocene-containing redox polymer anode

NASA Astrophysics Data System (ADS)

Bunte, Christine; Hussein, Laith; Urban, Gerald A.

2014-02-01

Novel single compartment Glucose/O2 biofuel cells (BFCs) were developed using immobilized enzymes and the mediated electron transfer (MET) approach. The bioanode was prepared through a ferrocene-containing redox polymer crosslinked in the presence of a biocatalyst on a glassy carbon support. Here, the redox polymer can physically entrap the enzyme and prevent it from leaching. Additionally it provides a biocompatible microenvironment and thus could extend the life time of enzyme. On the other side, the mediated biocathode was prepared based on bilirubin oxidase and 2,2‧-azinobis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS2-) system which has been physically entrapped in Nafion matrix and then adsorbed directly on a highly porous, conductive and functionalized buckypaper (fBP). Both electrodes were characterized physically and electrochemically. Employing these electrodes, the resulting BFC generates an open circuit voltage (Voc) of approximately 0.550 V and a peak power density of 26 μW cm-2 at 0.2 V at 37 °C in quiescent O2-saturated physiological buffer containing 5 mM glucose. The cell sustains a load up to 225 μA cm-2. Moreover, a high short circuit current (Isc) of 300 μA cm-2 is approached. This BFC can operate in mild conditions without using any toxic materials which makes it attractive for implantable devices.

A screen-printed carbon electrode modified with gold nanoparticles, poly(3,4-ethylenedioxythiophene), poly(styrene sulfonate) and a molecular imprint for voltammetric determination of nitrofurantoin.

PubMed

Dechtrirat, Decha; Yingyuad, Peerada; Prajongtat, Pongthep; Chuenchom, Laemthong; Sriprachuabwong, Chakrit; Tuantranont, Adisorn; Tang, I-Ming

2018-04-23

A molecularly imprinted polymer (MIP) and a nanocomposite prepared from gold nanoparticles (AuNP) and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) were deposited on a screen-printed carbon electrode (SPCE). The nanocomposite was prepared by one-pot simultaneous in-situ formation of AuNPs and PEDOT:PSS and was then inkjet-coated onto the SPCE. The MIP film was subsequently placed on the modified SPCE by co-electrodeposition of o-phenylenediamine and resorcinol in the presence of the antibiotic nitrofurantoin (NFT). Using differential pulse voltammetry (DPV), response at the potential of ~ 0.1 V (vs. Ag/AgCl) is linear in 1 nM to 1000 nM NFT concentration range, with a remarkably low detection limit (at S/N = 3) of 0.1 nM. This is two orders of magnitude lower than that of the control MIP sensor without the nanocomposite interlayer, thus showing the beneficial effect of AuNP-PEDOT:PSS. The electrode is highly reproducible (relative standard deviation 3.1% for n = 6) and selective over structurally related molecules. It can be re-used for at least ten times and was found to be stable for at least 45 days. It was successfully applied to the determination of NFT in (spiked) feed matrices and gave good recoveries. Graphical abstract Schematic representation of a voltammetric sensor for the determination of nitrofurantoin. The sensor is based on a screen-printed carbon electrode (SPCE) modified with an inkjet-printed gold nanoparticles-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) nanocomposite and a molecularly imprinted polymer.

Metaldehyde removal from aqueous solution by adsorption and ion exchange mechanisms onto activated carbon and polymeric sorbents.

PubMed

Tao, Bing; Fletcher, Ashleigh J

2013-01-15

Metaldehyde removal from aqueous solution was evaluated using granular activated carbon (GAC), a non-functionalised hyper-cross-linked polymer Macronet (MN200) and an ion-exchange resin (S957) with sulfonic and phosphonic functional groups. Equilibrium experimental data were successfully described by Freundlich isotherm models. The maximum adsorption capacity of S957 (7.5 g metaldehyde/g S957) exceeded those of MN200 and GAC. Thermodynamic studies showed that sorption of metaldehyde onto all sorbents is endothermic and processes are controlled by entropic rather than enthalpic changes. Kinetic experiments demonstrated that experimental data for MN200 and GAC obey pseudo-second order models with rates limited by particle diffusion. Comparatively, S957 was shown to obey a pseudo-first order model with a rate-limiting step of metaldehyde diffusion through the solid/liquid interface. Results obtained suggest that metaldehyde adsorption onto MN200 and GAC are driven by hydrophobic interactions and hydrogen bonding, as leaching tendencies were high since no degradation of metaldehyde occurred. Conversely, adsorption of metaldehyde onto S957 occurs via ion-exchange processes, where sulfonic and phosphonic functionalities degrade adsorbed metaldehyde molecules and failure to detect metaldehyde in leaching studies for S957 supports this theory. Consequently, the high adsorption capacity and absence of leaching indicate S957 is promising for metaldehyde removal from source water. Copyright © 2012 Elsevier B.V. All rights reserved.

Abstracts of AF Materials Laboratory Reports. January 1973 - December 1973

DTIC Science & Technology

1974-07-01

substituted polymers with aryl ether , ketone and sulfone units in the backbone has been studied. The best resins seem to have come from simple...exposed to hostile environments such as heat aging plus salt spray, humid aging , humid aging and elevated temperature cycling, and fatigue...unclassified results of materials and process and radome characterization effort. Environmental exposure including thermal aging resulted in significant

Materials and Manufacturing Challenges of Direct Methanol Fuel Cells

DTIC Science & Technology

2009-04-27

SPSf. Figure 5 shows four basic polymers in which benzimidazole (BIm), amino- benzimidazole (ABIm), nitrobenzimidazole (NBIm), and perimidine (PImd...Membranes Based on Sulfonated Polyetheretherketone and Polysulfone Bearing Benzimidazole Side Groups for Fuel Cells,” Electrochemistry Communications...Bearing Benzimidazole Side Groups for Direct Methanol Fuel Cells,” Electrochemical and Solid State Letters, Vol. 10, 2007, p. B70-B73. [12] Fu, Y.-Z

Diorganotin-based coordination polymers derived from sulfonate/phosphonate/phosphonocarboxylate ligands.

PubMed

Shankar, Ravi; Jain, Archana; Kociok-Köhn, Gabriele; Molloy, Kieran C

2011-02-21

The reactions of diorganotin precursors [R(2)Sn(OR(1))(OSO(2)R(1))](n) [R = R(1) = Me (1); R = Me, R(1) = Et (2)] with an equimolar amount of t-butylphosphonic acid (RT, 8-10 h) in methanol result in the formation of identical products, of composition [(Me(2)Sn)(3)(O(3)PBu(t))(2)(O(2)P(OH)Bu(t))(2)](n) (3). On the other hand, a similar reaction of 2, when carried out in dichloromethane, affords [(Me(2)Sn)(3)(O(3)PBu(t))(2)(OSO(2)Et)(2)·MeOH](n) (4). A plausible mechanism implicating the role of solvent in the formation of these compounds has been put forward. In addition, the synthesis of [(Me(2)Sn)(3)(O(3)PCH(2)CH(2)COOMe)(2)(OSO(2)Me)(2)](n) (5) and [R(2)Sn(O(2)P(OH)CH(2)CH(2)COOMe)(OSO(2)R(1))](n) [R = Et, R(1) = Me (6); R = (n)Bu, R(1) = Et (7)] has been achieved by reacting 1 and related diorganotin(alkoxy)alkanesulfonates with 3-phosphonopropionic acid in methanol. The formation of a methylpropionate functionality on the phosphorus center in these structural frameworks results from in situ esterification of the carboxylic group. X-ray crystallographic studies of 1-7 are presented. The structures of 1 and 2 represent one-dimensional (1D) coordination polymers composed of alternate [Sn-O](2) and [Sn-O-S-O](2) cyclic rings formed by μ(2)-alkoxo and sulfonate ligands, respectively. For 3-5 and 7, variable bonding modes of phosphonate and/or sulfonate ligands afford the construction of two- and three-dimensional self-assemblies that are comprised of trinuclear tin entities with an Sn(3)P(2)O(6) core as well as [Sn-O-P-O](2) and/or [Sn-O-S-O](2) rings. The formation of a 1D coordination polymer in 6 is unique in terms of repeating eight-membered cyclic rings containing Sn, O, P, and S heteroatoms. The contribution from hydrogen-bonding interactions is also found to be significant in these structures.

Self-Healing Polymer Dielectric for a High Capacitance Gate Insulator.

PubMed

Ko, Jieun; Kim, Young-Jae; Kim, Youn Sang

2016-09-14

Self-healing materials are required for development of various flexible electronic devices to repair cracks and ruptures caused by repetitive bending or folding. Specifically, a self-healing dielectric layer has huge potential to achieve healing electronics without mechanical breakdown in flexible operations. Here, we developed a high performance self-healing dielectric layer with an ionic liquid and catechol-functionalized polymer which exhibited a self-healing ability for both bulk and film states under mild self-healing conditions at 55 °C for 30 min. Due to the sufficient ion mobility of the ionic liquid in the polymer matrix, it had a high capacitance value above 1 μF/cm(2) at 20 Hz. Moreover, zinc oxide (ZnO) thin-film transistors (TFTs) with a self-healing dielectric layer exhibited a high field-effect mobility of 16.1 ± 3.07 cm(2) V(-1) s(-1) at a gate bias of 3 V. Even after repetitive self-healing of the dielectric layer from mechanical breaking, the electrical performance of the TFTs was well-maintained.

Hierarchical composites of sulfonated graphene-supported vertically aligned polyaniline nanorods for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Ma, Biao; Zhou, Xiao; Bao, Hua; Li, Xingwei; Wang, Gengchao

2012-10-01

Hierarchical composites of sulfonated graphene-supported vertically aligned polyaniline nanorods (sGNS/PANI) are successfully synthesized via interfacial polymerization of aniline monomers in the presence of sulfonated graphene nanosheets (sGNS). The FE-SEM images indicate that the morphologies of sGNS/PANI composites can be controlled by adjusting the concentration of aniline monomers. FTIR and Raman spectra reveal that aligned PANI nanorod arrays for sGNS/PANI exhibit higher degree of conjugation compared with pristine PANI nanorods. The hierarchical composite based on the two-electrode cell possesses higher specific capacitance (497 F g-1 at 0.2 A g-1), better rate capability and cycling stability (5.7% capacitance loss after 2000 cycles) than those of pristine PANI nanorods.

Phenol and Benzoate Metabolism by Pseudomonas putida: Regulation of Tangential Pathways

PubMed Central

Feist, Carol F.; Hegeman, G. D.

1969-01-01

Catechol occurs as an intermediate in the metabolism of both benzoate and phenol by strains of Pseudomonas putida. During growth at the expense of benzoate, catechol is cleaved ortho (1,2-oxygenase) and metabolized via the β-ketoadipate pathway; during growth at the expense of phenol or cresols, the catechol or substituted catechols formed are metabolized by a separate pathway following meta (2,3-oxygenase) cleavage of the aromatic ring of catechol. It is possible to explain the mutually exclusive occurrence of the meta and ortho pathway enzymes in phenol- and benzoate-grown cells of P. putida on the basis of differences in the mode of regulation of these two pathways. By use of both nonmetabolizable inducers and blocked mutants, gratuitous synthesis of some of the meta pathway enzymes was obtained. All four enzymes of the meta pathway are induced by the primary substrate, cresol or phenol, or its analogue. Three enzymes of the ortho pathway that catalyze the conversion of catechol to β-ketoadipate enol-lactone are induced by cis,cis-muconate, produced from catechol by 1,2-oxygenase-mediated cleavage. Observations on the differences in specificity of induction and function of the two pathways suggest that they are not really either tangential or redundant. The meta pathway serves as a general mechanism for catabolism of various alkyl derivatives of catechol derived from substituted phenolic compounds. The ortho pathway is more specific and serves primarily in the catabolism of precursors of catechol and catechol itself. PMID:5354952

Coupling and Reactions of 5-Hydroxyconiferyl Alcohol in Lignin Formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elder, Thomas; Berstis, Laura; Beckham, Gregg T.

The catechol alcohols, caffeyl and 5-hydroxyconiferyl alcohol, may be incorporated into lignin either naturally or through genetic manipulation. Due to the presence of o-OH groups, these compounds form benzodioxanes, a departure from the interunit connections found in lignins derived from the cinnamyl alcohols. In nature, lignins composed of caffeyl and 5-hydroxyconiferyl alcohol are linear homopolymers and, as such, may have properties that make them amenable for use in value-added products, such as lignin-based carbon fibers. In the current work, results from density functional theory calculations for the reactions of 5-hydroxyconiferyl alcohol, taking stereochemistry into account, are reported. Dehydrogenation and quinone methide formation are found to be thermodynamically favored for 5-hydroxyconiferyl alcohol, over coniferyl alcohol. The comparative energetics of the rearomatization reactions suggest that the formation of the benzodioxane linkage is under kinetic control. Ring-opening reactions of the benzodioxane groups show that the bond dissociation enthalpy of themore » $$\\alpha$$-O cleavage reaction is lower than that of the $$\\beta$$-O reaction. In conclusion, the catechol lignins represent a novel form of the polymer that may offer new opportunities for bioproducts and genetic targets.« less

Coupling and Reactions of 5-Hydroxyconiferyl Alcohol in Lignin Formation

DOE PAGES

Elder, Thomas; Berstis, Laura; Beckham, Gregg T.; ...

2016-05-28

The catechol alcohols, caffeyl and 5-hydroxyconiferyl alcohol, may be incorporated into lignin either naturally or through genetic manipulation. Due to the presence of o-OH groups, these compounds form benzodioxanes, a departure from the interunit connections found in lignins derived from the cinnamyl alcohols. In nature, lignins composed of caffeyl and 5-hydroxyconiferyl alcohol are linear homopolymers and, as such, may have properties that make them amenable for use in value-added products, such as lignin-based carbon fibers. In the current work, results from density functional theory calculations for the reactions of 5-hydroxyconiferyl alcohol, taking stereochemistry into account, are reported. Dehydrogenation and quinone methide formation are found to be thermodynamically favored for 5-hydroxyconiferyl alcohol, over coniferyl alcohol. The comparative energetics of the rearomatization reactions suggest that the formation of the benzodioxane linkage is under kinetic control. Ring-opening reactions of the benzodioxane groups show that the bond dissociation enthalpy of themore » $$\\alpha$$-O cleavage reaction is lower than that of the $$\\beta$$-O reaction. In conclusion, the catechol lignins represent a novel form of the polymer that may offer new opportunities for bioproducts and genetic targets.« less

Bioavailability of phenanthrene in the presence of birnessite-mediated catechol polymers.

PubMed

Russo, Fabio; Rao, Maria A; Gianfreda, Liliana

2005-07-01

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of aquatic and terrestrial environments. In soil, their fate may be affected by interactions with the soil biological community and soil colloids. This study was conducted to investigate the fate of phenanthrene (Phe), selected as a representative PAH, in simplified model systems, which simulate processes naturally occurring in soil. Phe was interacted with catechol (Cat), an orthodiphenol, and common intermediate in the microbial degradation of PAHs, and birnessite (Bir), an abiotic strong oxidative catalyst abundant in soil. Two experimental conditions were investigated: Cat (5 mM)+Bir (1 mg ml(-1))+Phe (0.05 mg ml(-1)) mixed at the same time and incubated for 24 h at 25 degrees C (Cat-Bir-Phe) and Cat+Bir incubated for 24 h at 25 degrees C before Phe addition and then incubated for a further 24 h (Cat-Bir+Phe). After incubation, the systems were analysed for residual Cat and Phe, supplied with a selected Phe-degrading mixed bacterial culture, and then the microbial degradation of Phe and the growth of cells were monitored. Complex phenomena simultaneously occurred. Cat was completely removed after a 24-h incubation with Bir, and no interference by Phe in the Bir-mediated transformation of Cat was observed. Elemental analysis and UV-Vis and Fourier transfer infrared spectra showed that Cat transformation by Bir produced soluble and insoluble polymeric aggregates involving Phe. The hydrocarbon also interacted with the surfaces of Bir either previously coated (Cat-Bir+Phe sample) or not by Cat polymers. When a Phe-degrading bacterial culture was added to the systems after Bir-mediated Cat polymerisation, a different behaviour was observed in terms of Phe consumption and bacterial growth, thus suggesting differentiated availability of Phe to the microbial cells. The hydrocarbon was completely transformed in the presence of Bir and/or Bir covered by Cat polymers. By contrast a reduced degradation was measured when the Phe was involved in the polymerisation of Cat and entrapped in the Cat polymers (Cat-Bir-Phe). Although Cat showed a toxic, lethal effect on the bacterial cells, microbial growth was observed in the presence of Cat and Cat polymers, as the only C source. The mechanism leading to the different availability of Phe in the presence of Cat and Bir is still not clear. Further investigations are requested to provide more insight into such a complex phenomenon.

Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides

PubMed Central

Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

2012-01-01

A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments. PMID:23181614

Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols.

PubMed

Couturier, Jean-Philippe; Wischerhoff, Erik; Bernin, Robert; Hettrich, Cornelia; Koetz, Joachim; Sütterlin, Martin; Tiersch, Brigitte; Laschewsky, André

2016-05-03

Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye.

Proton-conducting membrane based on epoxy resin-poly(vinyl alcohol)-sulfosuccinic acid blend and its nanocomposite with sulfonated multiwall carbon nanotubes for fuel-cell application

NASA Astrophysics Data System (ADS)

Kakati, Nitul; Das, Gautam; Yoon, Young Soo

2016-01-01

A blend of poly(vinyl alcohol) (PVA) with diglycidyl ether of bisphenol-A (DGB) in the presence of sulfosuccinic acid (SSA) was investigated as hydrolytically-stable proton-conducting membrane. The PVA modification was carried out by varying the DGB:SSA ratio (20:20, 10:20, and 5:20). A nanocomposite of the blend (20:20) was prepared with sulfonated multiwall carbon nanotubes (viz., 1, 3 and 5 wt%). The water uptake behavior and the proton conductivity of the prepared membranes were evaluated. The ionic conductivity of the membranes and the water uptake behavior depended on the s-MWCNT and the DGB contents. The ionic conductivity showed an enhancement for the blend and for the nanocomposite membrane as compared to the pristine polymer.

Radiation-grafted fluoropolymers soaked with imidazolium-based ionic liquids for high-performance ionic polymer-metal composite actuators.

PubMed

Lee, Jang Yeol; Wang, Hyuck Sik; Yoon, Bye Ri; Han, Man Jae; Jho, Jae Young

2010-11-01

On purpose to develop a polymer actuator with high stability in air-operation as well as large bending displacement, a series of ionic polymer-metal composites (IPMC) was constructed with poly(styrene sulfonate)-grafted fluoropolymers as ionomeric matrix and immidazolium-based ionic liquids (IL) as inner solvent. The prepared IPMC actuators exhibited greatly enhanced bending displacement compared to Nafion-based actuators. The actuators were stable in air-operation, maintaining initial displacement for up to 10(4) cycles or 24 h. Investigating the material parameters and morphology of the IPMCs, high ion exchange capacity of the ionomers resulted in high ion conductivity and robust electrode of IPMC, which synergistically contributed to the high bending performance. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Imparting in situ stability to displacing fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, S.C.

1970-07-14

An aqueous preslug containing electrolyte an/or isopropanol was injected before a micellar-polymer flood to inhibit the tendency of the formation to degrade the flood. Berea cores were saturated with water from Henry lease in Illinois (18,000 ppm TDS), flooded with Henry crude (7 cp viscosity at 72/sup 0/F, specific gravity 0.843), and waterflooded with Henry water. A recovery of 86.3 percent OIP was obtained with the following preslug, micellar slug, and polymer flood. The preslug contained water from the water reservoir in Palestine, Illinois (400 ppm TDS) and sodium hydroxide. Ammonium petroleum sulfonate, Henry crude, isopropanol, nonyl phenol, sodium hydroxide,more » and Palestine water were combined to form the water-external micellar slug. The polymer flood was composed of Pusher 530, Palestine water, isopropanol, and ammonium thiocyanide.« less

Construction of a multifunctional coating consisting of phospholipids and endothelial progenitor cell-specific peptides on titanium substrates

NASA Astrophysics Data System (ADS)

Chen, Huiqing; Li, Xiaojing; Zhao, Yuancong; Li, Jingan; Chen, Jiang; Yang, Ping; Maitz, Manfred F.; Huang, Nan

2015-08-01

A phospholipid/peptide polymer (PMMDP) with phosphorylcholine groups, endothelial progenitor cell (EPC)-specific peptides and catechol groups was anchored onto a titanium (Ti) surface to fabricate a biomimetic multifunctional surface. The PMMDP coating was characterized by X-ray photoelectron spectroscopy (XPS), water contact angle measurements and atomic force microscopy (AFM), respectively. The amount of PMMDP coating on the Ti surface was quantified by using the quartz crystal microbalance with dissipation (QCM-D). Interactions between blood components and the coated and bare Ti substrates were evaluated by platelet adhesion and activation assays and fibrinogen denaturation test using platelet rich plasma (PRP). The results revealed that the PMMDP-modified surface inhibited fibrinogen denaturation and reduced platelet adhesion and activation. EPC cell culture on the PMMDP-modified surface showed increased adhesion and proliferation of EPCs when compared to the cells cultured on untreated Ti surface. The inhibition of fibrinogen denaturation and platelet adhesion and support of EPCs attachment and proliferation indicated that this coating might be beneficial for future applications in blood-contacting implants, such as vascular stents.

Adsorption of catechol and comparative solutes on hydroxyapatite.

PubMed

Chirdon, William M; O'Brien, William J; Robertson, Richard E

2003-08-15

Contemporary medical and dental adhesives often have difficulty sticking to wet surfaces or weaken with long-term exposure to water. Substantial research has been dedicated to finding a means of achieving adhesion in an aqueous environment. A study evaluates the adsorption of catechol relative to other chemical groups as means of gauging how effective they may be as adsorptive groups in adhesives. Contact angle and surface-tension measurements of solutions of catechols and other chemical groups were used to determine their works of adhesion. Adsorption isotherms were also constructed to ascertain Langmuir constants. Solutes containing catechol groups were compared to solutes containing other polar groups to see how well catechol adsorbs to hydroxyapatite, the mineral component of bones and teeth, relative to other chemical groups found in adhesives. The results of this study show that catechol and molecules containing catechol groups have higher rates and energies of adsorption to hydroxyapatite than do groups such as alcohols, amines, and carboxylic acids. Copyright 2003 Wiley Periodicals, Inc.

Carbonic anhydrase inhibitors: guaiacol and catechol derivatives effectively inhibit certain human carbonic anhydrase isoenzymes (hCA I, II, IX and XII).

PubMed

Scozzafava, Andrea; Passaponti, Maurizio; Supuran, Claudiu T; Gülçin, İlhami

2015-01-01

Carbonic anhydrases (CAs) are widespread metalloenzymes in higher vertebrates including humans. A series of phenolic compounds, including guaiacol, 4-methylguaiacol, 4-propylguaiacol, eugenol, isoeugenol, vanillin, syringaldehyde, catechol, 3-methyl catechol, 4-methyl catechol and 3-methoxy catechol were investigated for their inhibition of all the catalytically active mammalian isozymes of the Zn(2+)-containing CA (EC 4.2.1.1). All the phenolic compounds effectively inhibited human carbonic anhydrase isoenzymes (hCA I, II, IX and XII), with Kis in the range of 2.20-515.98 μM. The various isozymes showed diverse inhibition profiles. Among the tested phenolic derivatives, compounds 4-methyl catechol and 3-methoxy catechol showed potent activity as inhibitors of the tumour-associated transmembrane isoforms (hCA IX and XII) in the submicromolar range, with high selectivity. The results obtained from this research may lead to the design of more effective carbonic anhydrase isoenzyme inhibitors (CAIs) based on such phenolic compound scaffolds.

Effect of "bridge" on the performance of organic-inorganic crosslinked hybrid proton exchange membranes via KH550

NASA Astrophysics Data System (ADS)

Han, Hailan; Li, Hai Qiang; Liu, Meiyu; Xu, Lishuang; Xu, Jingmei; Wang, Shuang; Ni, Hongzhe; Wang, Zhe

2017-02-01

A series of novel organic-inorganic crosslinked hybrid proton exchange membranes were prepared using sulfonated poly(arylene ether ketone sulfone) polymers containing carboxyl groups (C-SPAEKS), (3-aminopropyl)-triethoxysilane (KH550), and tetraethoxysilane (TEOS). KH550 acted as a "bridge" after reacting with carboxyl and sulfonic groups of C-SPAEKS to form covalent and ionic crosslinked structure between the C-SPAEKS and SiO2 phase. The crosslinked hybrid membranes (C-SPAEKS/K-SiO2) were characterized by FT-IR spectroscopy, TGA, and electrochemistry, etc. The thermal stability, mechanical properties and proton conductivity of the crosslinked hybrid membranes were improved by the presence of both crosslinked structure and inorganic phase. The proton conductivity of C-SPAEKS/K-SiO2-8 was recorded as 0.110 S cm-1, higher than that of Nafion® (0.028 S cm-1) at 120 °C. Moreover, the methanol permeability of the C-SPAEKS/K-SiO2-8 was measured as 3.86 × 10-7 cm2 s-1, much lower than that of Nafion® 117 membranes (29.4 × 10-7 cm2 s-1) at 25 °C.

Improvement in the mechanical properties, proton conductivity, and methanol resistance of highly branched sulfonated poly(arylene ether)/graphene oxide grafted with flexible alkylsulfonated side chains nanocomposite membranes

NASA Astrophysics Data System (ADS)

Liu, Dong; Peng, Jinhua; Li, Zhuoyao; Liu, Bin; Wang, Lei

2018-02-01

Sulfonated polymer/graphene oxide (GO) nanocomposites exhibit excellent properties as proton exchange membranes. However, few investigations on highly branched sulfonated poly(arylene ether)s (HBSPE)/GO nanocomposites as proton exchange membranes are reported. In order to obtain HBSPE-based nanocomposite membranes with better dispersibility and properties, a novel GO containing flexible alkylsulfonated side chains (SGO) is designed and prepared for the first time in this work. The HBSPE/SGO nanocomposite membranes with excellent dispersibility are successfully prepared. The properties of these membranes, including the mechanical properties, ion-exchange capacity, water uptake, proton conductivity, and methanol resistance, are characterized. The nanocomposite membranes exhibit higher tensile strength (32.67 MPa), higher proton conductivity (0.39 S cm-1 at 80 °C) and lower methanol permeability (4.89 × 10-7 cm2 s-1) than the pristine membrane. The nanocomposite membranes also achieve a higher maximum power density (82.36 mW cm-2) than the pristine membrane (67.85 mW cm-2) in single-cell direct methanol fuel cell (DMFC) tests, demonstrating their considerable potential for applications in DMFCs.

Novel structure design of composite proton exchange membranes with continuous and through-membrane proton-conducting channels

NASA Astrophysics Data System (ADS)

Wang, Hang; Tang, Chenxiao; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Li, Hongjun

2017-10-01

The primary goal of this study is to develop a high-performanced proton exchange membrane with the characteristics of through-membrane and continuous solution blown nanofibers as proton-conducting channels. The curled sulfonated phenolphthalein poly (ether sulfone) and poly (vinylidene fluoride) nanofibers were separately fabricated through the solution blowing process which is a new nanofiber fabricating method with high productivity, then they were fabricated into a sandwich-structured mat. Then this sandwich-structured mat was hot-pressed to form the designed structure using different melting temperatures of the two polymers by melting and making poly (vinylidene fluoride) flow into the phenolphthalein poly (ether sulfone) nanofiber mat. The characteristics of the composite membrane, such as morphology and performance of the membrane, were investigated. The characterization results proved the successful preparation of the membrane structure. Performance results showed that the novel structured membrane with through-membrane nanofibers significantly improved water swelling and methanol permeability, though its conductivity is lower than that of Nafion, the cell performance showed comparable results. Therefore, the novel structure design can be considered as a promising method for preparing of proton exchange membranes.

Preparation of Pt/polypyrrole-para toluene sulfonate hydrogen peroxide sensitive electrode for the utilizing as a biosensor.

PubMed

Çete, Servet; Bal, Özgür

2013-12-01

A film electrode with electropolymerization of pyrrole (Py) and para-toluene sulfonate (pTS) as a anionic dopant is prepared and its sensitivity to hydrogen peroxide is investigated. The polypyrrole is deposited on a 0.5 cm(2) Pt plate an electrochemically prepared pTS ion-doped polypyrrole film by scanning the electrode potential between - 0.8 and + 0.8 V at a scan rate of 20 mV/s. The electrode's sensitivity to hydrogen peroxide is investigated at room temperature using 0.1 M phosphate buffer at pH 7.5. The working potential is found as a 0.3 V. The concentrations of pyrrole and pTS are 50mM M and 25 mM. Polypyrrole was coated on the electrode surface within 10 cycles. İmmobilization of glucose oxidase carried out on Pt/polypyrrole-para toluene sulfonate (Pt/PPy-pTS) film by cross-linking with glutaraldehyde. The morphology of electrodes was characterized by SEM and AFM. Moreover, contact angle measurements were made with 1 μL water of polymer film and enzyme electrode. It has shown that enzyme electrode is very sensitive against to glucose.

A Survey and Evaluation of Chemical Warfare Agent-Decontaminants and Decontamination

DTIC Science & Technology

1984-10-15

0.21 citric acid monohydrate, 0.05% detergent, and 98.251 water) all contain calcium hypochlorite and have been used for decontaminating agents from...water repellent chemicals consist of an aluminum salt of a saturated carboxylic acid (such as format, acetate, palmitate, or stearate) mixed with...been conducted. Sawdust, soil, silicone, coal dust, amine or sulfonic acid -containing polymers, organic and inorganic ion-exchange materials, and metal

Sulfonated poly(ether ether ketone)/poly(vinyl alcohol) sensitizing system for solution photogeneration of small Ag, Au, and Cu crystallites.

PubMed

Korchev, A S; Shulyak, T S; Slaten, B L; Gale, W F; Mills, G

2005-04-28

Illumination of air-free aqueous solutions containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol) with 350 nm light results in benzophenone ketyl radicals of the polyketone. The polymer radicals form with a quantum yield 0.02 and decay with a second-order rate constant 6 orders of magnitude lower than that of typical alpha-hydroxy radicals. Evidence is presented that the polymeric benzophenone ketyl radicals reduce Ag+, Cu2+, and AuCl4- to metal particles of nanometer dimensions. Decreases in the reduction rates with increasing Ag(I), Cu(II), and Au(III) concentrations are explained using a kinetic model in which the metal ions quench the excited state of the polymeric benzophenone groups, which forms the macromolecular radicals. Quenching is fastest for Ag+, whereas Cu2+ and AuCl4- exhibit similar rate constants. Particle formation becomes more complex as the number of equivalents needed to reduce the metal ions increases; the Au(III) system is an extreme case where the radical reactions operate in parallel with secondary light-initiated and thermal reduction channels. For each metal ion, the polymer-initiated photoreactions produce crystallites possessing distinct properties, such as a very strong plasmon in the Ag case or the narrow size distribution exhibited by Au particles.

TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

NASA Astrophysics Data System (ADS)

Sawada, Shin-ichi; Suzuki, Akihiro; Terai, Takayuki; Maekawa, Yasunari

2010-04-01

We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene- co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 °C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 °C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6×10 -1 S/cm.

Electro-Osmosis and Water Uptake in Polymer Electrolytes in Equilibrium with Water Vapor at Low Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallagher, K. G.; Pivovar, B. S.; Fuller, T. F.

2009-01-01

Water uptake and electro-osmosis are investigated to improve the understanding and aid the modeling of water transport in proton-exchange membrane fuel cells (PEMFCs) below 0 C. Measurements of water sorption isotherms show a significant reduction in the water capacity of polymer electrolytes below 0 C. This reduced water content is attributed to the lower vapor pressure of ice compared to supercooled liquid water. At -25 C, 1100 equivalent weight Nafion in equilibrium with vapor over ice has 8 moles of water per sulfonic acid group. Measurements of the electro-osmotic drag coefficient for Nafion and both random and multiblock copolymer sulfonatedmore » poly(arylene ether sulfone) (BPSH) chemistries are reported for vapor equilibrated samples below 0 C. The electro-osmotic drag coefficient of BPSH chemistries is found to be {approx}0.4, and that of Nafion is {approx}1. No significant temperature effect on the drag coefficient is found. The implication of an electro-osmotic drag coefficient less than unity is discussed in terms of proton conduction mechanisms. Simulations of the ohmically limited current below 0 C show that a reduced water uptake below 0 C results in a significant decrease in PEMFC performance.« less

Electrochemosensor for trace analysis of perfluorooctane sulfonate in water based on a molecularly imprinted poly o-phenylenediamine polymer.

PubMed

Karimian, Najmeh; Stortini, Angela Maria; Moretto, Ligia Maria; Costantino, Claudio; Bogialli, Sara; Ugo, Paolo

2018-06-18

This work is aimed at developing an electrochemical sensor for the sensitive and selective detection of trace levels of perfluorooctane sulfonate (PFOS) in water. Contamination of waters by perfluorinated alkyl substances (PFAS) is a problem of global concern due to their suspected toxicity and ability to bioaccumulate. PFOS is the perfluorinated compound of major concern, as it has the lowest suggested control concentrations. The sensor reported here is based on a gold electrode modified with a thin coating of a molecularly imprinted polymer (MIP), prepared by anodic electropolymerization of o-phenylenediamine (o-PD) in the presence of PFOS as the template. Activation of the sensor is achieved by template removal with suitable a solvent mixture. Voltammetry, a quartz crystal microbalance, scanning electron microscopy and elemental analysis were used to monitor the electropolymerization process, template removal and binding of the analyte. Ferrocenecarboxylic acid (FcCOOH) has been exploited as an electrochemical probe able to generate analytically useful voltammetric signals by competing for the binding sites with PFOS, as the latter is not electroactive. The sensor has a low detection limit (0.04 nM), a satisfactory selectivity, and is reproducible and repeatable, giving analytical results in good agreement with those obtained by HPLC-MS/MS analyses.

Chemical Modification and Structure-property Relationships of Acrylic and Ionomeric Thermoplastic Elastomer Gels

NASA Astrophysics Data System (ADS)

Vargantwar, Pruthesh Hariharrao

Block copolymers (BCs) have remained at the forefront of materials research due to their versatility in applications ranging from hot-melt/pressure-sensitive adhesives and impact modifiers to compatibilizing agents and vibration-dampening/nanotemplating media. Of particular interest are macromolecules composed of two or more chemically dissimilar blocks covalently linked together to form triblock or pentablock copolymers. If the blocks are sufficiently incompatible and the copolymer behaves as a thermoplastic elastomer, the molecules can spontaneously self-assemble to form nanostructured materials that exhibit shape memory due to the formation of a supramolecular network. The BCs of these types are termed as conventional. When BCs contain blocks having ionic moieties such as sulfonic acid groups, they are termed as block ionomers. Designing new systems based on either conventional or ionic BCs, characterizing their structure-property relationships and later using them as electroacive polymers form the essential objectives of this work. Electroactive polymers (EAPs) exhibit electromechanical actuation when stimulated by an external electric field. In the first part of this work, it is shown that BCs resolve some of the outstanding problems presently encountered in the design of two different classes of EAP actuators: dielectric elastomers (DEs) and ionic polymer metal composites (IPMCs). All-acrylic triblock copolymer gels used as DEs actuate with high efficacy without any requirement of mechanical prestrain and, thus, eliminate the need for bulky and heavy hardware essential with prestrained dielectric actuators, as well as material problems associated with stress relaxation. The dependence of actuation behavior on gel morphology as evaluated from mechanical and microstructure studies is observed. In the case of IPMCs, ionic BCs employed in this study greatly facilitate processing compared to other contenders such as NafionRTM, which is commonly used in this class of EAPs. The unique copolymer investigated here (i) retains its mechanical integrity when highly solvated by polar solvents, (ii) demonstrates a high degree of actuation when tested in a cantilever configuration, and (iii) avoids the shortcomings of back-relaxation/overshoot within the testing conditions when used in combination with an appropriate solvent. In the second part of this work, two chemical strategies to design midblock sulfonated block ionomers are explored. In one case, selective sulfonation of the midblocks in triblock copolymers is achieved via a dioxane:sulfur trioxide chemistry, while in the other acetyl sulfate is used for the same purpose. Excellent control on the degree of sulfonation (DOS) is achieved. The block ionomers swell in different solvents while retaining their mechanical integrity. They show disorder-order, order-order, and order-reduced order morphological transitions as DOS varies. These transitions in morphologies are reflected in their thermal behavior as well. The microstructures show periodicity, which is, again, a function of DOS. The transitions are explained in terms of the molar volume expansion and volume densification of the blocks on sulfonation. The ionic levels, morphology and periodicity in microstructure are important for applications such as actuators, sensors and fuel cell membranes. The ability to tune these aspects in the ionomers designed in this work make them potential candidates for these applications.

Defining an optimal surface chemistry for pluripotent stem cell culture in 2D and 3D

NASA Astrophysics Data System (ADS)

Zonca, Michael R., Jr.

Surface chemistry is critical for growing pluripotent stem cells in an undifferentiated state. There is great potential to engineer the surface chemistry at the nanoscale level to regulate stem cell adhesion. However, the challenge is to identify the optimal surface chemistry of the substrata for ES cell attachment and maintenance. Using a high-throughput polymerization and screening platform, a chemically defined, synthetic polymer grafted coating that supports strong attachment and high expansion capacity of pluripotent stem cells has been discovered using mouse embryonic stem (ES) cells as a model system. This optimal substrate, N-[3-(Dimethylamino)propyl] methacrylamide (DMAPMA) that is grafted on 2D synthetic poly(ether sulfone) (PES) membrane, sustains the self-renewal of ES cells (up to 7 passages). DMAPMA supports cell attachment of ES cells through integrin beta1 in a RGD-independent manner and is similar to another recently reported polymer surface. Next, DMAPMA has been able to be transferred to 3D by grafting to synthetic, polymeric, PES fibrous matrices through both photo-induced and plasma-induced polymerization. These 3D modified fibers exhibited higher cell proliferation and greater expression of pluripotency markers of mouse ES cells than 2D PES membranes. Our results indicated that desirable surfaces in 2D can be scaled to 3D and that both surface chemistry and structural dimension strongly influence the growth and differentiation of pluripotent stem cells. Lastly, the feasibility of incorporating DMAPMA into a widely used natural polymer, alginate, has been tested. Novel adhesive alginate hydrogels have been successfully synthesized by either direct polymerization of DMAPMA and methacrylic acid blended with alginate, or photo-induced DMAPMA polymerization on alginate nanofibrous hydrogels. In particular, DMAPMA-coated alginate hydrogels support strong ES cell attachment, exhibiting a concentration dependency of DMAPMA. This research provides a new avenue for stem cell culture and maintenance using an optimal organic-based chemistry.

Bioelectrochemical control of neural cell development on conducting polymers.

PubMed

Collazos-Castro, Jorge E; Polo, José L; Hernández-Labrado, Gabriel R; Padial-Cañete, Vanesa; García-Rama, Concepción

2010-12-01

Electrically conducting polymers hold promise for developing advanced neuroprostheses, bionic systems and neural repair devices. Among them, poly(3, 4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) exhibits superior physicochemical properties but biocompatibility issues have limited its use. We describe combinations of electrochemical and molecule self-assembling methods to consistently control neural cell development on PEDOT:PSS while maintaining very low interfacial impedance. Electro-adsorbed polylysine enabled long-term neuronal survival and growth on the nanostructured polymer. Neurite extension was strongly inhibited by an additional layer of PSS or heparin, which in turn could be either removed electrically or further coated with spermine to activate cell growth. Binding basic fibroblast growth factor (bFGF) to the heparin layer inhibited neurons but promoted proliferation and migration of precursor cells. This methodology may orchestrate neural cell behavior on electroactive polymers, thus improving cell/electrode communication in prosthetic devices and providing a platform for tissue repair strategies. Copyright © 2010 Elsevier Ltd. All rights reserved.

Stimuli Responsive Morphological Changes of Pnipa Polymer Brushes Synthesized on Silicon Substrate

NASA Astrophysics Data System (ADS)

Huda, Muhammad Nurul; Kabir, A. N. M. Hamidul

2013-08-01

High-density polymer brushes were grown from the silicon surface by atom transfer radical polymerization of Poly(N-isopropylacrylamide) (PNIPA) at different polymerization conditions. PNIPA brushes were prepared using Copper (I) Chloride/tris(2-(dimetylamino)ethyl)amine (Me6TREN) as a catalytic system in DMSO at 20°C. Free polymer formed during the brush formation was characterized by gel permeation chromatography. The grafting densities up to 0.52 chains/nm2 were obtained. The layer thickness of polymer brush increases with the increase of conversion of the monomer conversion as well as polymerization time. Atomic force microscopy and air bubble contact angle under pH solution were employed to study the surface morphology, reversible conformational changes of and stimulus-response behavior. PNIPA brushes exhibited a different nanomorphology after treatment with different pH solution. It also revealed a unique reversible wetting behavior with pH. The reversible properties of the PNIPA brushes can be used to regulate the adsorption of the sulfonated PS nanoparticles.

Flotability and flotation separation of polymer materials modulated by wetting agents.

PubMed

Wang, Hui; Wang, Chong-qing; Fu, Jian-gang; Gu, Guo-hua

2014-02-01

The surface free energy, surface tension and contact angles were performed to investigate the properties of wetting agents. Adsorption of wetting agents changes wetting behavior of polymer resins. Flotability of polymer materials modulated by wetting agents was studied, and wetting agents change significantly flotability of polymer materials. The flotability decreases with increasing the concentration of wetting agents, and the wetting ability is lignin sulfonate (LS)>tannic acid (TA)>methylcellulose (MC)>triton X-100 (TX-100) (from strong to weak). There is significant difference in the flotability between polymer resins and plastics due to the presence of additives in the plastics. Flotation separation of two-component and multicomponent plastics was conducted based on the flotability modulated by wetting agents. The two-component mixtures can be efficiently separated using proper wetting agent through simple flotation flowsheet. The multicomponent plastic mixtures can be separated efficiently through multi-stage flotation using TA and LS as wetting agents, and the purity of separated component was above 94%, and the recovery was more than 93%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Novel neural interface for implant electrodes: improving electroactivity of polypyrrole through MWNT incorporation.

PubMed

Green, R A; Williams, C M; Lovell, N H; Poole-Warren, L A

2008-04-01

Multi-walled carbon nanotubes (MWNTs) can be incorporated into conductive polymers to produce superior materials for neural interfaces with high interfacial areas, conductivity and electrochemical stability. This paper explores the addition of MWNTs to polypyrrole (PPy) through two methods, layering and codeposition. Conductivity of PPy doped with polystyrene sulfonate (PSS), a commonly used dopant, was improved by 50% when MWNTs were layered with PPy/PSS. The film electrochemical stability was improved from 38% activity to 66% activity after 400 cycles of oxidation and reduction. Growth inhibition assays indicated that MWNTs are not growth inhibitory. The electroactive polymer-MWNT composites produced demonstrate properties that suggest they are promising candidates for biomedical electrode coatings.

Effects of countercations on the structures and redox and spectroscopic properties of diruthenium catecholate complexes with ligand-unsupported Ru-Ru bonds.

PubMed

Chang, Ho-Chol; Mochizuki, Katsunori; Kitagawa, Susumu

2005-05-30

The molecular structures and physicochemical properties of diruthenium complexes with ligand-unsupported Ru-Ru bonds, generally formulated as [A2{Ru2(DTBCat)4}] (DTB = 3,5- or 3,6-di-tert-butyl; Cat(2-) = catecholate), were studied in detail by changing the countercations. First, the binding structures of the cations in a family of [{A(DME)n}2{Ru2(3,5-DTBCat)4}] (n = 2 for A+ = Li+ and Na+ and n = 1 for A+ = K+ and Rb+) were systematically examined to reveal the effects of the cations on the molecular structures and electrochemical properties. Second, the complex (n-Bu4N)2[Ru2(3,6-DTBCat)4] with a cation-free structure was synthesized using tetra-n-butylammonium cations. The complex clearly demonstrates first that the ligand-unsupported Ru-Ru bonds are essentially stabilized by the dianionic nature of the catecholate derivatives without any other bridging or supporting species. In contrast, the redox potentials and absorption spectra of the complexes can sensitively respond to the countercations depending upon the polarity of the solvents.

Strategic Design of an Effective beta-Lactamase Inhibitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pattanaik, P.; Bethel, C; Hujer, A

In an effort to devise strategies for overcoming bacterial beta-lactamases, we studied LN-1-255, a 6-alkylidene-2'-substituted penicillin sulfone inhibitor. By possessing a catecholic functionality that resembles a natural bacterial siderophore, LN-1-255 is unique among beta-lactamase inhibitors. LN-1-255 combined with piperacillin was more potent against Escherichia coli DH10B strains bearing bla(SHV) extended-spectrum and inhibitor-resistant beta-lactamases than an equivalent amount of tazobactam and piperacillin. In addition, LN-1-255 significantly enhanced the activity of ceftazidime and cefpirome against extended-spectrum cephalosporin and Sme-1 containing carbapenem-resistant clinical strains. LN-1-255 inhibited SHV-1 and SHV-2 beta-lactamases with nm affinity (K(I) = 110 +/- 10 and 100 +/- 10 nm,more » respectively). When LN-1-255 inactivated SHV beta-lactamases, a single intermediate was detected by mass spectrometry. The crystal structure of LN-1-255 in complex with SHV-1 was determined at 1.55A resolution. Interestingly, this novel inhibitor forms a bicyclic aromatic intermediate with its carbonyl oxygen pointing out of the oxyanion hole and forming hydrogen bonds with Lys-234 and Ser-130 in the active site. Electron density for the 'tail' of LN-1-255 is less ordered and modeled in two conformations. Both conformations have the LN-1-255 carboxyl group interacting with Arg-244, yet the remaining tails of the two conformations diverge. The observed presence of the bicyclic aromatic intermediate with its carbonyl oxygen positioned outside of the oxyanion hole provides a rationale for the stability of this inhibitory intermediate. The 2'-substituted penicillin sulfone, LN-1-255, is proving to be an important lead compound for novel beta-lactamase inhibitor design.« less

Synthesis and Properties of a Precision Sulfonated Trimethylene-Styrene Polyelectrolyte

NASA Astrophysics Data System (ADS)

Kennemur, Justin; Neary, William; Bohlmann, Michele; Kendrick, Aaron

We recently reported successful ring-opening metathesis polymerization of 4-phenylcyclopentene to afford a precision ethylene-styrene type copolymer with a phenyl branch at exactly every fifth carbon along the backbone following mild hydrogenation of the backbone olefins. (http://dx.doi.org/10.1002/marc.201600121) Compared to polystyrene, this material shows a markedly reduced glass transition temperature (Tg 17 °C) and remains amorphous. We have now extended the function of this polymer via sulfonation of the phenyl branches to produce a precision polyelectrolyte with an ionic charge spacing at every fifth carbon along the chain. The reduced yet precise charge density coupled with the low Tg of the native material translates into a variety of properties that are unique to this system and potentially useful as an addition to the limited set of available polyelectrolyte materials. Synthetic aspects in addition to thermal and mechanical properties will be discussed. Graduate Student.

Vinyl Sulfonate Esters: Efficient Chain Transfer Agents for the 3D-Printing of Tough Photopolymers without Retardation.

PubMed

Seidler, Konstanze; Griesser, Markus; Kury, Markus; Reghunathan, Harikrishna; Dorfinger, Peter; Koch, Thomas; Svirkova, Anastasiya; Marchetti-Deschmann, Martina; Stampfl, Jürgen; Moszner, Norbert; Gorsche, Christian; Liska, Robert

2018-05-04

Photoinitiated radical polymer network formation is lacking freedom for tailored network design. Resulting inhomogeneous network architectures and brittle material behavior of such glassy-type networks limit the commercial application of photopolymers in 3D printing, biomedicine or microelectronics. An ester-activated vinyl sulfonate ester (EVS) is presented for the rapid formation of tailored methacrylate-based networks with nearly no retardation, reduced shrinkage stress, high monomer conversion and improved material toughness. Laser flash photolysis followed by theoretical calculations and photoreactor studies elucidate the fast chain transfer reaction and exceptional regulating ability of EVS. Final photopolymer networks exhibit high tensile strength, improved elongation at break and high impact resistance, while maintaining high modulus and hardness at ambient conditions. These findings make EVS an exceptional candidate for the 3D printing of tough photopolymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A New Acceptor (N-type) Polyphenylenevinylene Building Block: SF-PPV-I

NASA Technical Reports Server (NTRS)

Wang, Yiqing; Fan, Zhen; Taft, Charles; Sun, Sam-Shajing

2002-01-01

A new sulfone derivatized acceptor (n-type) polyphenylenevinylene "SF-PPV" with nano meter sizes and functional terminals has been synthesized and characterized. The SF-PPV-I that contains hydrocarbon alkyl-sulfone moieties has a strong photoluminescence in both solution and in solid thin film states. In dichloromethane, the 5-10 nm sized SF-PPV has a maximum emission at about 530 nm with excitation maximum at about 490 nm. UV-VIS shows a absorption peak onsite at about 500 nm. Optical spectroscopy and electrochemical studies revealed that the SF-PPV-I has an LUMO level at about -3.6 eV (relative to vacuum), and an HOMO level at about -6.1 eV. The average size (length) of SF-PPV-I can be controlled on the nano meter scale via synthetic means. The SF-PPV has the potential in developing polymer based supramolecular opto-electronic semiconductor devices.

Radiation grafted and sulfonated (FEP-g-polysterene) - An alternative to perfluorinated membranes for PEM fuel cells?

NASA Astrophysics Data System (ADS)

Buechi, F. N.; Gupta, B.; Rouilly, M.; Hauser, P. C.; Chapiro, A.; Scherer, G. G.

Partially fluorinated proton exchange membranes (PEMs) were synthesized for fuel cell applications by simultaneous radiation grafting of styrene on FEP films followed by sulfonation. Properties of the synthesized membranes can be tailored by varying the degree of grafting and crosslinking. The performance of these membranes was tested in H2/O2 fuel cells. Long time testing showed steady performance for high grafted membranes over periods of more than 300 h at a cell temperature of 60 C. Low grafted membranes and the Morgane CDS membrane showed considerable decay of cell power on the same time scale. A fast degradation of all membranes occurred at a cell temperature of 80 C. It is noted that grafting in film form makes this process a potentially cheap and easy technique for the preparation of solid polymer fuel cell electrolytes.

Water Transport in Bicontinuous, Phase-Separated Membranes Made from Reactive Block Copolymers

DTIC Science & Technology

2014-12-01

polyurethane foam impregnated with activated carbon, a design that allows perspiration to evaporate while chemical agents are adsorbed onto the activated... dispersed into a minimal volume (4–5 drops) of ethanol. The catalyst solution was then added to the polymer solution while stirring rapidly. The solution...substituted styrene monomer; one interior block with units of other styrene monomers which have been sulfonated; non- dispersible and solid in water

Potential Metabolic Activation of a Representative C2-Alkylated Polycyclic Aromatic Hydrocarbon 6-Ethylchrysene Associated with the Deepwater Horizon Oil Spill in Human Hepatoma (HepG2) Cells

PubMed Central

2016-01-01

Exposure to polycyclic aromatic hydrocarbons (PAHs) is the major human health hazard associated with the Deepwater Horizon oil spill. C2-Chrysenes are representative PAHs present in crude oil and could contaminate the food chain. We describe the metabolism of a C2-chrysene regioisomer, 6-ethylchrysene (6-EC), in human HepG2 cells. The structures of the metabolites were identified by HPLC-UV-fluorescence detection and LC-MS/MS. 6-EC-tetraol isomers were identified as signature metabolites of the diol-epoxide pathway. O-Monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and N-acetyl-l-cysteine(NAC)-6-EC-ortho-quinone were discovered as signature metabolites of the ortho-quinone pathway. Potential dual metabolic activation of 6-EC involving the formation of bis-electrophiles, i.e., a mono-diol-epoxide and a mono-ortho-quinone within the same structure, bis-diol-epoxides, and bis-ortho-quinones was observed as well. The identification of 6-EC-tetraol, O-monomethyl-O-monosulfonated-6-EC-catechol, its monohydroxy products, and NAC-6-EC-ortho-quinone supports potential metabolic activation of 6-EC by P450 and AKR enzymes followed by metabolic detoxification of the ortho-quinone through interception of its redox cycling capability by catechol-O-methyltransferase and sulfotransferase enzymes. The tetraols and catechol conjugates could be used as biomarkers of human exposure to 6-EC resulting from oil spills. PMID:27054409

Preparation of Highly Conductive Yarns by an Optimized Impregnation Process

NASA Astrophysics Data System (ADS)

Amba Sankar, K. N.; Mohanta, Kallol

2017-12-01

We report the development of the electrical conductivity in textile yarns through impregnation and post-treatment of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The conductive polymer is deposited on fibers, which fills the gap space within the hierarchical structure of the yarns. Organic nonpolar solvents act as reducing agent to increase the density of PEDOT moieties on the yarns, galvanizing increment in conductivity values. Post-treatment by ethylene glycol transforms the resonance configuration of the conductive moieties of conjugated polymer, which helps in further enhancement of electrical conductivity of the yarns. We have optimized the method in terms of loading and conformal change of the polymer to have a lesser resistance of the coated conductive yarns. The minimum resistance achieved has a value of 77 Ωcm-1. This technique of developing conductivity in conventional yarns enables retaining the flexibility of yarns and feeling of softness which would find suitable applications for wearable electronics.

Redox-active charge carriers of conducting polymers as a tuner of conductivity and its potential window

PubMed Central

Park, Han-Saem; Ko, Seo-Jin; Park, Jeong-Seok; Kim, Jin Young; Song, Hyun-Kon

2013-01-01

Electric conductivity of conducting polymers has been steadily enhanced towards a level worthy of being called its alias, “synthetic metal”. PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate)), as a representative conducting polymer, recently reached around 3,000 S cm−1, the value to open the possibility to replace transparent conductive oxides. The leading strategy to drive the conductivity increase is solvent annealing in which aqueous solution of PEDOT:PSS is treated with an assistant solvent such as DMSO (dimethyl sulfoxide). In addition to the conductivity enhancement, we found that the potential range in which PEDOT:PSS is conductive is tuned wider into a negative potential direction by the DMSO-annealing. Also, the increase in a redox-active fraction of charge carriers is proposed to be responsible for the enhancement of conductivity in the solvent annealing process. PMID:23949091

Preparation of Highly Conductive Yarns by an Optimized Impregnation Process

NASA Astrophysics Data System (ADS)

Amba Sankar, K. N.; Mohanta, Kallol

2018-03-01

We report the development of the electrical conductivity in textile yarns through impregnation and post-treatment of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The conductive polymer is deposited on fibers, which fills the gap space within the hierarchical structure of the yarns. Organic nonpolar solvents act as reducing agent to increase the density of PEDOT moieties on the yarns, galvanizing increment in conductivity values. Post-treatment by ethylene glycol transforms the resonance configuration of the conductive moieties of conjugated polymer, which helps in further enhancement of electrical conductivity of the yarns. We have optimized the method in terms of loading and conformal change of the polymer to have a lesser resistance of the coated conductive yarns. The minimum resistance achieved has a value of 77 Ωcm-1. This technique of developing conductivity in conventional yarns enables retaining the flexibility of yarns and feeling of softness which would find suitable␣applications for wearable electronics.

The Role of Hydrophobicity in the Cellular Uptake of Negatively Charged Macromolecules.

PubMed

Abou Matar, Tamara; Karam, Pierre

2018-02-01

It is generally accepted that positively charged molecules are the gold standard to by-pass the negatively charged cell membrane. Here, it is shown that cellular uptake is also possible for polymers with negatively charged side chains and hydrophobic backbones. Specifically, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene], a conjugated polyelectrolyte with sulfonate, as water-soluble functional groups, is shown to accumulate in the intracellular region. When the polymer hydrophobic backbone is dissolved using polyvinylpyrrolidone, an amphiphilic macromolecule, the cellular uptake is dramatically reduced. The report sheds light on the fine balance between negatively charged side groups and the hydrophobicity of polymers to either enhance or reduce cellular uptake. As a result, these findings will have important ramifications on the future design of targeted cellular delivery nanocarriers for imaging and therapeutic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorptive detoxification of fermentation inhibitors in acid pretreated liquor using functionalized polymer designed by molecular simulation.

PubMed

Devendra, Leena P; Pandey, Ashok

2017-11-01

Acid pretreatment is the most common method employed in the lignocellulosic biorefinery leading to the separation of pentose and hexose sugar. The liquor obtained after pretreatment (acid pretreatment liquor or APL) needs to be detoxified prior to fermentation. The aim of this study was to design functional groups on a polymer matrix which are selective in their interaction to inhibitors with little or no specificity to sugars. Molecular modeling was used as a tool to design a suitable adsorbent for selective adsorption of inhibitors from a complex mixture of APL. Phenyl glycine-p-sulfonic acid loaded on chloromethylated polystyrene polymer was designed as an adsorbent for selective interaction with inhibitors. Experimental verification of the selectivity was successfully achieved. The current study provides insights on the adsorptive separation processes at the molecular level by design of specific adsorbent which can be tailor made for the better selectivity of the desired component.

Estrogen receptor-independent catechol estrogen binding activity: protein binding studies in wild-type, Estrogen receptor-alpha KO, and aromatase KO mice tissues.

PubMed

Philips, Brian J; Ansell, Pete J; Newton, Leslie G; Harada, Nobuhiro; Honda, Shin-Ichiro; Ganjam, Venkataseshu K; Rottinghaus, George E; Welshons, Wade V; Lubahn, Dennis B

2004-06-01

Primary evidence for novel estrogen signaling pathways is based upon well-documented estrogenic responses not inhibited by estrogen receptor antagonists. In addition to 17beta-E2, the catechol estrogen 4-hydroxyestradiol (4OHE2) has been shown to elicit biological responses independent of classical estrogen receptors in estrogen receptor-alpha knockout (ERalphaKO) mice. Consequently, our research was designed to biochemically characterize the protein(s) that could be mediating the biological effects of catechol estrogens using enzymatically synthesized, radiolabeled 4-hydroxyestrone (4OHE1) and 4OHE2. Scatchard analyses identified a single class of high-affinity (K(d) approximately 1.6 nM), saturable cytosolic binding sites in several ERalphaKO estrogen-responsive tissues. Specific catechol estrogen binding was competitively inhibited by unlabeled catechol estrogens, but not by 17beta-E2 or the estrogen receptor antagonist ICI 182,780. Tissue distribution studies indicated significant binding differences both within and among various tissues in wild-type, ERalphaKO, and aromatase knockout female mice. Ligand metabolism experiments revealed extensive metabolism of labeled catechol estrogen, suggesting that catechol estrogen metabolites were responsible for the specific binding. Collectively, our data provide compelling evidence for the interaction of catechol estrogen metabolites with a novel binding protein that exhibits high affinity, specificity, and selective tissue distribution. The extensive biochemical characterization of this binding protein indicates that this protein may be a receptor, and thus may mediate ERalpha/beta-independent effects of catechol estrogens and their metabolites.

Predictable Particle Engineering: Programming the Energy Level, Carrier Generation, and Conductivity of Core-Shell Particles.

PubMed

Yuan, Conghui; Wu, Tong; Mao, Jie; Chen, Ting; Li, Yuntong; Li, Min; Xu, Yiting; Zeng, Birong; Luo, Weiang; Yu, Lingke; Zheng, Gaofeng; Dai, Lizong

2018-06-20

Core-shell structures are of particular interest in the development of advanced composite materials as they can efficiently bring different components together at nanoscale. The advantage of this structure greatly relies on the crucial design of both core and shell, thus achieving an intercomponent synergistic effect. In this report, we show that decorating semiconductor nanocrystals with a boronate polymer shell can easily achieve programmable core-shell interactions. Taking ZnO and anatase TiO 2 nanocrystals as inner core examples, the effective core-shell interactions can narrow the band gap of semiconductor nanocrystals, change the HOMO and LUMO levels of boronate polymer shell, and significantly improve the carrier density of core-shell particles. The hole mobility of core-shell particles can be improved by almost 9 orders of magnitude in comparison with net boronate polymer, while the conductivity of core-shell particles is at most 30-fold of nanocrystals. The particle engineering strategy is based on two driving forces: catechol-surface binding and B-N dative bonding and having a high ability to control and predict the shell thickness. Also, this approach is applicable to various inorganic nanoparticles with different components, sizes, and shapes.

A Comprehensive Physical Impedance Model of Polymer Electrolyte Fuel Cell Cathodes in Oxygen-free Atmosphere.

PubMed

Obermaier, Michael; Bandarenka, Aliaksandr S; Lohri-Tymozhynsky, Cyrill

2018-03-21

Electrochemical impedance spectroscopy (EIS) is an indispensable tool for non-destructive operando characterization of Polymer Electrolyte Fuel Cells (PEFCs). However, in order to interpret the PEFC's impedance response and understand the phenomena revealed by EIS, numerous semi-empirical or purely empirical models are used. In this work, a relatively simple model for PEFC cathode catalyst layers in absence of oxygen has been developed, where all the equivalent circuit parameters have an entire physical meaning. It is based on: (i) experimental quantification of the catalyst layer pore radii, (ii) application of De Levie's analytical formula to calculate the response of a single pore, (iii) approximating the ionomer distribution within every pore, (iv) accounting for the specific adsorption of sulfonate groups and (v) accounting for a small H 2 crossover through ~15 μm ionomer membranes. The derived model has effectively only 6 independent fitting parameters and each of them has clear physical meaning. It was used to investigate the cathode catalyst layer and the double layer capacitance at the interface between the ionomer/membrane and Pt-electrocatalyst. The model has demonstrated excellent results in fitting and interpretation of the impedance data under different relative humidities. A simple script enabling fitting of impedance data is provided as supporting information.

Raman Microscopy Insights on the Out-of-Plane Electrical Transport of Carbon Nanotube-Doped PEDOT:PSS Electrodes for Solar Cell Applications.

PubMed

Mombrú, Dominique; Romero, Mariano; Faccio, Ricardo; Mombrú, Alvaro W

2018-03-08

In the present report, we focused on the study of the out-of-plane electrical transport of multiwalled carbon nanotube (MWCNT)-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) composites (PEDOT:PSS-MWCNTs) as electrodes for solar cell applications. The out-of-plane direct current and alternating current electrical transport, rarely studied but not less relevant, was additionally supported with in-plane and out-of-plane confocal Raman microscopy and grazing incidence small-angle X-ray scattering characterizations. The main relevance of our study is the monitoring of the polymer structure all across the polymeric film by using confocal Raman spectroscopy and its correlation with electrical transport. Modifications in the PEDOT benzenoid and quinoid conformations were observed in the vicinities of MWCNTs, and the enrichment of PSS at the indium tin oxide electrode interface was also evidenced. In consequence, the low MWCNT loadings into PEDOT:PSS lead to an increase of the out-of-plane conductivity, but the heavier MWCNT loadings lead to a drastic decrease. The tuning of the doping level of these polymer composites and the understanding of the interface structure are crucial to fabricate electrodes with higher out-of-plane conductivities for organic solar cell applications.

Synthesis, crystal structure and valence tautomerism of a 4,4‧-bipyridine-bridged one-dimensional chiral cobalt complex

NASA Astrophysics Data System (ADS)

Cheng, Wei-Qin; Li, Guo-Ling; Zhang, Ran; Ni, Zhong-Hai; Wang, Wen-Feng; Sato, Osamu

2015-05-01

A linear-chain cobalt coordination polymer, [Co(2,3-LH2)2(4,4‧-bipy)]ṡ2H2Oṡ4,4‧-bipy]n (1) (2,3-LH2 = 2,3-tetrahydroxy-9,10-dimethyl-9,10-dihydro- 9,10-ethanoanthracene, 4,4‧-bipy = 4,4‧-bipyridine), has been synthesized and structurally characterized. Single-crystal X-ray analysis reveals that complex 1 is a chiral polymer assemblied from achiral components. The complex 1 crystallizes in the chiral space group P3221 and the central Co ion has a slightly distorted octahedral coordination environment. The temperature dependence of magnetic susceptibility indicates that the complex 1 undergoes valence tautomeric interconversion between low-spin ls-[CoIII(2,3-LH2Cat)(2,3-LH2SQ)] and high-spin hs-[CoII(2,3-LH2SQ)2] (2,3-LH2Cat = 2,3-LH2catecholate, 2,3-LH2SQ = 2,3-LH2semiquinone).

Morphogen Electrochemically Triggered Self-Construction of Polymeric Films Based on Mussel-Inspired Chemistry.

PubMed

Maerten, Clément; Garnier, Tony; Lupattelli, Paolo; Chau, Nguyet Trang Thanh; Schaaf, Pierre; Jierry, Loïc; Boulmedais, Fouzia

2015-12-15

Inspired by the strong chemical adhesion mechanism of mussels, we designed a catechol-based electrochemically triggered self-assembly of films based on ethylene glycol molecules bearing catechol groups on both sides and denoted as bis-catechol molecules. These molecules play the role of morphogens and, in contrast to previously investigated systems, they are also one of the constituents, after reaction, of the film. Unable to interact together, commercially available poly(allylamine hydrochloride) (PAH) chains and bis-catechol molecules are mixed in an aqueous solution and brought in contact with an electrode. By application of defined potential cycles, bis-catechol molecules undergo oxidation leading to molecules bearing "reactive" quinone groups which diffuse toward the solution. In this active state, the quinones react with amino groups of PAH through Michael addition and Schiff's base condensation reaction. The application of cyclic voltammetry (CV) between 0 and 500 mV (vs Ag/AgCl, scan rate of 50 mV/s) of a PAH/bis-catechol solution results in a fast self-construction of a film that reaches a thickness of 40 nm after 60 min. The films present a spiky structure which is attributed to the use of bis-functionalized molecules as one component of the films. XPS measurements show the presence of both PAH and bis-catechol cross-linked together in a covalent way. We show that the amine/catechol ratio is an important parameter which governs the film buildup. For a given amine/catechol ratio, it does exist an optimum CV scan rate leading to a maximum of the film thickness as a function of the scan rate.

Polymer-Based Protein Engineering: Synthesis and Characterization of Armored, High Graft Density Polymer-Protein Conjugates.

PubMed

Carmali, Sheiliza; Murata, Hironobu; Cummings, Chad; Matyjaszewski, Krzysztof; Russell, Alan J

2017-01-01

Atom transfer radical polymerization (ATRP) from the surface of a protein can generate remarkably dense polymer shells that serve as armor and rationally tune protein function. Using straightforward chemistry, it is possible to covalently couple or display multiple small molecule initiators onto a protein surface. The chemistry is fine-tuned to be sequence specific (if one desires a single targeted site) at controlled density. Once the initiator is anchored on the protein surface, ATRP is used to grow polymers on protein surface, in situ. The technique is so powerful that a single-protein polymer conjugate molecule can contain more than 90% polymer coating by weight. If desired, stimuli-responsive polymers can be "grown" from the initiated sites to prepare enzyme conjugates that respond to external triggers such as temperature or pH, while still maintaining enzyme activity and stability. Herein, we focus mainly on the synthesis of chymotrypsin-polymer conjugates. Control of the number of covalently coupled initiator sites by changing the stoichiometric ratio between enzyme and the initiator during the synthesis of protein-initiator complexes allowed fine-tuning of the grafting density. For example, very high grafting density chymotrypsin conjugates were prepared from protein-initiator complexes to grow the temperature-responsive polymers, poly(N-isopropylacrylamide), and poly[N,N'-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate]. Controlled growth of polymers from protein surfaces enables one to predictably manipulate enzyme kinetics and stability without the need for molecular biology-dependent mutagenesis. © 2017 Elsevier Inc. All rights reserved.

Heterogeneous Organo-Catalysis: Sustainable Pathways to ...

EPA Pesticide Factsheets

Glucose and fructose are among the most abundant plant-derived materials1 and have been converted into useful building units often used in the drug discovery and polymer architecture.2 Unfortunately, most of these conversions require mineral acids and complex heterogeneous catalysis systems which suffer from the diminished activity and recyclability issues.3 Herein, we report a highly reactive and inexpensive heterogeneous sulfonated graphitic carbon nitride (Sg-CN), endowed with strong acidity that readily transforms carbohydrates to furanics. The ready availability and benign nature of the material and its stability over the several reaction cycles renders this catalyst very useful in organic synthesis, polymer industry and in the preparation of drug precursors. Poster presentation at the 253rd American Chemical Society (ACS) National meeting in San Francisco, CA

Catalytic molecularly imprinted polymer membranes: development of the biomimetic sensor for phenols detection.

PubMed

Sergeyeva, T A; Slinchenko, O A; Gorbach, L A; Matyushov, V F; Brovko, O O; Piletsky, S A; Sergeeva, L M; Elska, G V

2010-02-05

Portable biomimetic sensor devices for the express control of phenols content in water were developed. The synthetic binding sites mimicking active site of the enzyme tyrosinase were formed in the structure of free-standing molecularly imprinted polymer membranes. Molecularly imprinted polymer membranes with the catalytic activity were obtained by co-polymerization of the complex Cu(II)-catechol-urocanic acid ethyl ester with (tri)ethyleneglycoldimethacrylate, and oligourethaneacrylate. Addition of the elastic component oligourethaneacrylate provided formation of the highly cross-linked polymer with the catalytic activity in a form of thin, flexible, and mechanically stable membrane. High accessibility of the artificial catalytic sites for the interaction with the analyzed phenol molecules was achieved due to addition of linear polymer (polyethyleneglycol Mw 20,000) to the initial monomer mixture before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) were formed. The cross-linked component of the semi-IPN was represented by the highly cross-linked catalytic molecularly imprinted polymer, while the linear one was represented by polyethyleneglycol Mw 20,000. Extraction of the linear polymer from the fully formed semi-IPN resulted in formation of large pores in the membranes' structure. Concentration of phenols in the analyzed samples was detected using universal portable device oxymeter with the oxygen electrode in a close contact with the catalytic molecularly imprinted polymer membrane as a transducer. The detection limit of phenols detection using the developed sensor system based on polymers-biomimics with the optimized composition comprised 0.063 mM, while the linear range of the sensor comprised 0.063-1 mM. The working characteristics of the portable sensor devices were investigated. Storage stability of sensor systems at room temperature comprised 12 months (87%). As compared to traditional methods of phenols detection the developed sensor system is characterized by simplicity of operation, compactness, and low cost. Copyright 2009 Elsevier B.V. All rights reserved.

A Low-Cost and High-Performance Sulfonated Polyimide Proton-Conductive Membrane for Vanadium Redox Flow/Static Batteries.

PubMed

Li, Jinchao; Yuan, Xiaodong; Liu, Suqin; He, Zhen; Zhou, Zhi; Li, Aikui

2017-09-27

A novel side-chain-type fluorinated sulfonated polyimide (s-FSPI) membrane is synthesized for vanadium redox batteries (VRBs) by high-temperature polycondensation and grafting reactions. The s-FSPI membrane has a vanadium ion permeability that is over an order of magnitude lower and has a proton selectivity that is 6.8 times higher compared to those of the Nafion 115 membrane. The s-FSPI membrane possesses superior chemical stability compared to most of the linear sulfonated aromatic polymer membranes reported for VRBs. Also, the vanadium redox flow/static batteries (VRFB/VRSB) assembled with the s-FSPI membranes exhibit stable battery performance over 100- and 300-time charge-discharge cycling tests, respectively, with significantly higher battery efficiencies and lower self-discharge rates than those with the Nafion 115 membranes. The excellent physicochemical properties and VRB performance of the s-FSPI membrane could be attributed to the specifically designed molecular structure with the hydrophobic trifluoromethyl groups and flexible sulfoalkyl pendants being introduced on the main chains of the membrane. Moreover, the cost of the s-FSPI membrane is only one-fourth that of the commercial Nafion 115 membrane. This work opens up new possibilities for fabricating high-performance proton-conductive membranes at low costs for VRBs.

Synthetic Design of Polysulfone Membranes: Morphological Effect on Property and Performance in Flow Batteries

NASA Astrophysics Data System (ADS)

Gindt, Brandon

This dissertation outlines a novel path towards improved understanding and function of proton exchange membranes (PEMs) for redox flow batteries, a large-scale battery storage device. This research uses synthetic methods and nanotechnology through two different approaches to prepare tailored polymer membranes: 1) Ion exchange membranes with enhanced chemical structures to promote membrane morphology on the nano-scale were prepared. Specifically, functional polysulfones (PSUs) were synthesized from different pre-sulfonated monomers. These PSUs have controlled placement and content of unique sulfonic acid moieties. PEMs were fabricated and characterized. The new PEMs showed desirable physical properties and performance in a vanadium redox flow battery (VRFB) cell. 2) Nanoporous PSU membranes were fabricated via post-hydrolysis of polylactide (PLA) from PLA-PSU-PLA triblock copolymer membranes. The controlled morphology and pore size of the resulting nanoporous membranes were evaluated by different microscopy and scattering techniques to understand structure-property relationships. Further, the resulting nanopore surface was chemically modified with sulfonic acid moieties. Membranes were analyzed and evaluated as separators for a VRFB. The chemically modified nanoporous PEMs exhibited unique behavior with respect to their ion conductivity when exposed to solutions of increasing acid concentration. In addition, the hierarchical micro-nanoporous membranes developed further showed promising structure and properties.

Synthesis and properties of reprocessable sulfonated polyimides cross-linked via acid stimulation for use as proton exchange membranes

NASA Astrophysics Data System (ADS)

Zhang, Boping; Ni, Jiangpeng; Xiang, Xiongzhi; Wang, Lei; Chen, Yongming

2017-01-01

Cross-linked sulfonated polyimides are one of the most promising materials for proton exchange membrane (PEM) applications. However, these cross-linked membranes are difficult to reprocess because they are insoluble. In this study, a series of cross-linkable sulfonated polyimides with flexible pendant alkyl side chains containing trimethoxysilyl groups is successfully synthesized. The cross-linkable polymers are highly soluble in common solvents and can be used to prepare tough and smooth films. Before the cross-linking reaction is complete, the membranes can be reprocessed, and the recovery rate of the prepared films falls within an acceptable range. The cross-linked membranes are obtained rapidly when the cross-linkable membranes are immersed in an acid solution, yielding a cross-linking density of the gel fraction of greater than 90%. The cross-linked membranes exhibit high proton conductivities and tensile strengths under hydrous conditions. Compared with those of pristine membranes, the oxidative and hydrolytic stabilities of the cross-linked membranes are significantly higher. The CSPI-70 membrane shows considerable power density in a direct methanol fuel cell (DMFC) test. All of these results suggest that the prepared cross-linked membranes have great potential for applications in proton exchange membrane fuel cells.

Inverted polymer solar cell based on MEH-PPV/PC61BM coupled with ZnO nanoparticles as electron transport layer

NASA Astrophysics Data System (ADS)

Salem, A. M. S.; El-Sheikh, S. M.; Harraz, Farid A.; Ebrahim, S.; Soliman, M.; Hafez, H. S.; Ibrahim, I. A.; Abdel-Mottaleb, M. S. A.

2017-12-01

In this work, we demonstrate the use of annealed sol-gel derived ZnO nanoparticles acting as electron transport layer (ETL) in inverted bulk heterojunction (BHJ) polymer solar cells (PSCs). We have examined the photovoltaic performance of devices based on poly(2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV):(6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) blend system employing the ZnO nanoparticles as an ETL with CuI as hole transport layer (HTL) in comparison to the case of using the conventional HTL of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) sulfonic acid (PEDOT:PSS). The effect of the presence of another layer of ZnO macrospheres attached to the ZnO nanoparticles is also investigated. The highest power conversion efficiency (PCE) value of 1.35% was achieved for device: ITO/ZnO nanoparticles/MEH-PPV:PC61BM/CuI/Ag, which is 275% more the value obtained when CuI was replaced by PEDOT:PSS. The comprehensive analyses on structural and optical characteristics including SEM, XRD, FTIR, PL and UV-vis spectroscopy indicated that the use of the ZnO nanoparticles alone as ETL, together with the CuI as HTL could effectively reduce trap-assisted recombination and charge accumulation at the interface, which is beneficial for the enhanced device performance.

'All-solid-state' electrochemistry of a protein-confined polymer electrolyte film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parthasarathy, Meera; Pillai, Vijayamohanan K.; Mulla, Imtiaz S.

2007-12-07

Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique 'all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe{sup 2+}-form of the entrapped proteinmore » is found to bind molecular oxygen more strongly than the native protein. In the 'all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry.« less

Structured Ionomer Thin Films at Water Interface: Molecular Dynamics Simulation Insight

DOE PAGES

Aryal, Dipak; Agrawal, Anupriya; Perahia, Dvora; ...

2017-08-23

Controlling the structure and dynamics of thin films of ionizable polymers at water interfaces is critical to their many applications. As the chemical diversity within one polymer is increased, controlling the structure and dynamics of the polymer, which is a key to their use, becomes a challenge. Here molecular dynamics simulations (MD) are used to obtain molecular insight into the structure and dynamics of thin films of one such macromolecule at the interface with water. The polymer consists of an ABCBA topology with randomly sulfonated polystyrene (C), tethered symmetrically to flexible poly(ethylene- r-propylene) blocks (B), and end-capped by a poly(more » t-butylstyrene) block (A). The compositions of the interfacial and bulk regions of thin films of the ABCBA polymers are followed as a function of exposure time to water. We find that interfacial rearrangements take place where buried ionic segments migrate toward the water interface. The hydrophobic blocks collapse and rearrange to minimize their exposure to water. In conclusion, the water that initially drives interfacial reengagements breaks the ionic clusters within the film, forming a dynamic hydrophilic internal network within the hydrophobic segments.« less

Ferroelectric polarization induces electronic nonlinearity in ion-doped conducting polymers

PubMed Central

Fabiano, Simone; Sani, Negar; Kawahara, Jun; Kergoat, Loïg; Nissa, Josefin; Engquist, Isak; Crispin, Xavier; Berggren, Magnus

2017-01-01

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is an organic mixed ion-electron conducting polymer. The PEDOT phase transports holes and is redox-active, whereas the PSS phase transports ions. When PEDOT is redox-switched between its semiconducting and conducting state, the electronic and optical properties of its bulk are controlled. Therefore, it is appealing to use this transition in electrochemical devices and to integrate those into large-scale circuits, such as display or memory matrices. Addressability and memory functionality of individual devices, within these matrices, are typically achieved by nonlinear current-voltage characteristics and bistability—functions that can potentially be offered by the semiconductor-conductor transition of redox polymers. However, low conductivity of the semiconducting state and poor bistability, due to self-discharge, make fast operation and memory retention impossible. We report that a ferroelectric polymer layer, coated along the counter electrode, can control the redox state of PEDOT. The polarization switching characteristics of the ferroelectric polymer, which take place as the coercive field is overcome, introduce desired nonlinearity and bistability in devices that maintain PEDOT in its highly conducting and fast-operating regime. Memory functionality and addressability are demonstrated in ferro-electrochromic display pixels and ferro-electrochemical transistors. PMID:28695197

Zwitterionic polymer functionalization of polysulfone membrane with improved antifouling property and blood compatibility by combination of ATRP and click chemistry.

PubMed

Xiang, Tao; Lu, Ting; Xie, Yi; Zhao, Wei-Feng; Sun, Shu-Dong; Zhao, Chang-Sheng

2016-08-01

The chemical compositions are very important for designing blood-contacting membranes with good antifouling property and blood compatibility. In this study, we propose a method combining ATRP and click chemistry to introduce zwitterionic polymer of poly(sulfobetaine methacrylate) (PSBMA), negatively charged polymers of poly(sodium methacrylate) (PNaMAA) and/or poly(sodium p-styrene sulfonate) (PNaSS), to improve the antifouling property and blood compatibility of polysulfone (PSf) membranes. Attenuated total reflectance-Fourier transform infrared spectra, X-ray photoelectron spectroscopy and water contact angle results confirmed the successful grafting of the functional polymers. The antifouling property and blood compatibility of the modified membranes were systematically investigated. The zwitterionic polymer (PSBMA) grafted membranes showed good resistance to protein adsorption and bacterial adhesion; the negatively charged polymer (PNaSS or PNaMAA) grafted membranes showed improved blood compatibility, especially the anticoagulant property. Moreover, the PSBMA/PNaMAA modified membrane showed both antifouling property and anticoagulant property, and exhibited a synergistic effect in inhibiting blood coagulation. The functionalization of membrane surfaces by a combination of ATRP and click chemistry is demonstrated as an effective route to improve the antifouling property and blood compatibility of membranes in blood-contact. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

PubMed

Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

2016-09-01

Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

Electric double-layer capacitors with tea waste derived activated carbon electrodes and plastic crystal based flexible gel polymer electrolytes

NASA Astrophysics Data System (ADS)

Suleman, M.; Deraman, M.; Othman, M. A. R.; Omar, R.; Hashim, M. A.; Basri, N. H.; Nor, N. S. M.; Dolah, B. N. M.; Hanappi, M. F. Y. M.; Hamdan, E.; Sazali, N. E. S.; Tajuddin, N. S. M.; Jasni, M. R. M.

2016-08-01

We report a novel configuration of symmetrical electric double-layer capacitors (EDLCs) comprising a plastic crystalline succinonitrile (SN) based flexible polymer gel electrolyte, incorporated with sodium trifluoromethane sulfonate (NaTf) immobilised in a host polymer poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP). The cost-effective activated carbon powder possessing a specific surface area (SSA) of ~ 1700 m2g-1 containing a large proportion of meso-porosity has been derived from tea waste to use as supercapacitor electrodes. The high ionic conductivity (~3.6×10-3 S cm-1 at room temperature) and good electrochemical stability render the gel polymer electrolyte film a suitable candidate for the fabrication of EDLCs. The performance of the EDLCs has been tested by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge-discharge studies. The performance of the EDLC cell is found to be promising in terms of high values of specific capacitance (~270 F g-1), specific energy (~ 36 Wh kg-1), and power density (~ 33 kW kg-1).

Cellulose nanofiber-embedded sulfonated poly (ether sulfone) membranes for proton exchange membrane fuel cells.

PubMed

Xu, Xianlin; Li, Rui; Tang, Chenxiao; Wang, Hang; Zhuang, Xupin; Liu, Ya; Kang, Weimin; Shi, Lei

2018-03-15

Cellulose nanofibers were embedded into sulfonated poly (ether sulfone) matrix to heighten the water retention and proton conductivity of proton exchange membranes (PEMs). Cellulose nanofibers were obtained by hydrolyzing cellulose acetate nanofibers, which were prepared via electrostatic-induction-assisted solution blow spinning. Morphology, thermal stability, and mechanical properties of the PEMs were investigated. The results showed that proton conductivity, water uptake, and methanol permeability of the composite membranes were improved. Hydrophilicity of the composite membranes was gradually improved with the addition of nanofibers. When the content of nanofibers was 5 wt%, the highest proton conductivity was 0.13 S/cm (80 °C, 100% RH). Therefore, the cellulose nanofiber could be used as support materials to enhance the performance of proton exchange membranes, the composite membranes have potential application in Direct methanol fuel cells (DMFCs). Copyright © 2017 Elsevier Ltd. All rights reserved.

Detection of Catechol by Potentiometric-Flow Injection Analysis in the Presence of Interferents

ERIC Educational Resources Information Center

Lunsford, Suzanne K.; Widera, Justyna; Zhang, Hong

2007-01-01

This article describes an undergraduate analytical chemistry experiment developed to teach instrumental lab skills while incorporating common interferents encountered in the real-world analysis of catechol. The lab technique incorporates potentiometric-flow injection analysis on a dibenzo-18-crown-6 dual platinum electrode to detect catechol in…

Crystallization and preliminary crystallographic analysis of the catechol 2,3-dioxygenase PheB from Bacillus stearothermophilus BR219

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugimoto, Keisuke; Matsufuzi, Kazuki; Ohnuma, Hiroaki

2006-02-01

PheB, an extradiol-cleaving catecholic dioxygenase, was crystallized by the hanging-drop vapour-diffusion method using PEG 4000 as a precipitant. The crystal belongs to the orthorhombic system, space group P2{sub 1}2{sub 1}2{sub 1}, and diffracts to 2.3 Å resolution. Class II extradiol-cleaving catecholic dioxygenase, a key enzyme of aromatic compound degradation in bacteria, cleaves the aromatic ring of catechol by adding two O atoms. PheB is one of the class II extradiol-cleaving catecholic dioxygenases and shows a high substrate specificity for catechol derivatives, which have one aromatic ring. In order to reveal the mechanism of the substrate specificity of PheB, PheB hasmore » been crystallized by the hanging-drop vapour-diffusion method using PEG 4000 as a precipitant. The space group of the obtained crystal was P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 65.5, b = 119.2, c = 158.7 Å. The crystal diffracted to 2.3 Å resolution.« less

Simultaneous determination of hydroquinone and catechol at gold nanoparticles mesoporous silica modified carbon paste electrode.

PubMed

Tashkhourian, J; Daneshi, M; Nami-Ana, F; Behbahani, M; Bagheri, A

2016-11-15

A new electrochemical sensor based on gold nanoparticles mesoporous silica modified carbon paste electrode (AuNPs-MPS) was developed for simultaneous determination of hydroquinone and catechol. Morphology and structure of the AuNPs-MPS were characterized by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical behavior of hydroquinone and catechol were investigated using square wave voltammetry and the results indicate that the electrochemical responses are improved significantly at the modified electrode. The observed oxidative peaks separation of about 120mV made possible the simultaneous determination of hydroquinone and catechol in their binary-mixture. Under the optimized condition, a linear dynamic range of 10.0μM-1.0mM range for hydroquinone with the detection limit of 1.2μM and from 30.0μM-1.0mM for catechol with the detection limit of 1.1μM were obtained. The applicability of the method was demonstrated by the recovery studies of hydroquinone and catechol in spiked tap water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure-property correlations of ion-containing polymers for fuel cell applications

NASA Astrophysics Data System (ADS)

Sproll, Véronique; Nagy, Gergely; Gasser, Urs; Balog, Sandor; Gustavsson, Sanna; Schmidt, Thomas J.; Gubler, Lorenz

2016-01-01

In order to investigate the structure-property correlations of grafted proton conducting membranes, the model system consisting of an ETFE base film grafted with polystyrene and subsequent sulfonation (ETFE-g-PSSA) along with crosslinked derivatives ETFE-g-P(SSA-co-DiPB) were synthesized. The characteristics of the final membranes were characterized by PFG-NMR diffusometry, in-plane conductivity and by investigations of the dimensional changes of the grafted membranes. The collected data were correlated with the inherent anisotropy of the ETFE base film.

Synthesis and characteristics of polyarylene ether sulfones

NASA Technical Reports Server (NTRS)

Viswanathan, R.; Johnson, B. C.; Ward, T. C.; Mcgrath, J. E.

1981-01-01

A method utilizing potassium carbonate/dimethyl acetamide, as base and solvent respectively, was used for the synthesis of several homopolymers and copolymers derived from various bisphenols. It is demonstrated that this method deviates from simple second order kinetics; this deviation being due to the heterogeneous nature of the reaction. Also, it is shown that a liquid induced crystallization process can improve the solvent resistance of these polymers. Finally, a Monte Carlo simulation of the triad distribution of monomers in nonequilibrium copolycondensation is discussed.

Tunable denture adhesives using biomimetic principles for enhanced tissue adhesion in moist environments.

PubMed

Gill, Simrone K; Roohpour, Nima; Topham, Paul D; Tighe, Brian J

2017-11-01

Nature provides many interesting examples of adhesive strategies. Of particular note, the protein glue secreted by marine mussels delivers high adhesion in wet and dynamic environments owing to existence of catechol moieties. As such, this study focuses on denture fixatives, where a non-zinc-containing commercial-based formulation has been judiciously modified by a biomimetic catechol-inspired polymer, poly(3,4-dihydroxystyrene/styrene-alt-maleic acid) in a quest to modulate adhesive performance. In vitro studies, in a lap-shear configuration, revealed that the catechol-modified components were able to enhance adhesion to both the denture base and hydrated, functional oral tissue mimic, with the resulting mode of failure prominently being adhesive rather than cohesive. These characteristics are desirable in prosthodontic fixative applications, for which temporary adhesion must be maintained, with ultimately an adhesive failure from the mucosal tissue surface preferred. These insights provide an experimental platform in the design of future biomimetic adhesive systems. Mussel adhesive proteins have proven to be promising biomimetic adhesive candidates for soft tissues and here for the first time we have adapted marine adhesive technology into a denture fixative application. Importantly, we have incorporated a soft tissue mimic in our in vitro adhesion technique that more closely resembles the oral mucosa than previously studied substrates. The novel biomimetic-modified adhesives showed the ability to score the highest adhesive bonding out of all the formulations included in this study, across all moisture levels. This paper will be of major interest to the Acta Biomaterialia readership since the study has illustrated the potential of biomimetic principles in the design of effective prosthodontic tissue adhesives in a series of purpose-designed in vitro experiments in the context of the challenging features of the oral environment. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (14)C-catechol in an agricultural soil.

PubMed

Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan

2014-07-01

Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (14)C-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (14)C-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (14)C-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (14)C-catechol was significantly lower than that of in earthworm-free soil indicating that (14)C-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (14)C by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (14)C-catecholic residues during gut passage of earthworm. Copyright © 2014 Elsevier Ltd. All rights reserved.

Printable polymer actuators from ionic liquid, soluble polyimide, and ubiquitous carbon materials.

PubMed

Imaizumi, Satoru; Ohtsuki, Yuto; Yasuda, Tomohiro; Kokubo, Hisashi; Watanabe, Masayoshi

2013-07-10

We present here printable high-performance polymer actuators comprising ionic liquid (IL), soluble polyimide, and ubiquitous carbon materials. Polymer electrolytes with high ionic conductivity and reliable mechanical strength are required for high-performance polymer actuators. The developed polymer electrolytes comprised a soluble sulfonated polyimide (SPI) and IL, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][NTf2]), and they exhibited acceptable ionic conductivity up to 1 × 10(-3) S cm(-1) and favorable mechanical properties (elastic modulus >1 × 10(7) Pa). Polymer actuators based on SPI/[C2mim][NTf2] electrolytes were prepared using inexpensive activated carbon (AC) together with highly electron-conducting carbon such as acetylene black (AB), vapor grown carbon fiber (VGCF), and Ketjen black (KB). The resulting polymer actuators have a trilaminar electric double-layer capacitor structure, consisting of a polymer electrolyte layer sandwiched between carbon electrode layers. Displacement, response speed, and durability of the actuators depended on the combination of carbons. Especially the actuators with mixed AC/KB carbon electrodes exhibited relatively large displacement and high-speed response, and they kept 80% of the initial displacement even after more than 5000 cycles. The generated force of the actuators correlated with the elastic modulus of SPI/[C2mim][NTf2] electrolytes. The displacement of the actuators was proportional to the accumulated electric charge in the electrodes, regardless of carbon materials, and agreed well with the previously proposed displacement model.

Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

1996-01-01

Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

Coarse-grained simulations of polyelectrolyte complexes: MARTINI models for poly(styrene sulfonate) and poly(diallyldimethylammonium)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vögele, Martin; Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt a. M.; Holm, Christian

2015-12-28

We present simulations of aqueous polyelectrolyte complexes with new MARTINI models for the charged polymers poly(styrene sulfonate) and poly(diallyldimethylammonium). Our coarse-grained polyelectrolyte models allow us to study large length and long time scales with regard to chemical details and thermodynamic properties. The results are compared to the outcomes of previous atomistic molecular dynamics simulations and verify that electrostatic properties are reproduced by our MARTINI coarse-grained approach with reasonable accuracy. Structural similarity between the atomistic and the coarse-grained results is indicated by a comparison between the pair radial distribution functions and the cumulative number of surrounding particles. Our coarse-grained models aremore » able to quantitatively reproduce previous findings like the correct charge compensation mechanism and a reduced dielectric constant of water. These results can be interpreted as the underlying reason for the stability of polyelectrolyte multilayers and complexes and validate the robustness of the proposed models.« less

New Insights into Perfluorinated Sulfonic-Acid Ionomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kusoglu, Ahmet; Weber, Adam Z.

In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers’ complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem frommore » correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films are presented. Throughout, the impact of PFSA chemistry and side-chain is also discussed to present a broader perspective.« less

Composite Electrolyte Membranes from Partially Fluorinated Polymer and Hyperbranched, Sulfonated Polysulfone

PubMed Central

Subianto, Surya; Roy Choudhury, Namita; Dutta, Naba

2013-01-01

Macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) was done with various proportions of sulfonic acid terminated, hyperbranched polysulfone (HPSU) with a view to prepare ion conducting membranes. The PVDF-co-HFP was first chemically modified by dehydrofluorination and chlorosulfonation in order to make the membrane more hydrophilic as well as to introduce unsaturation, which would allow crosslinking of the PVDF-co-HFP matrix to improve the stability of the membrane. The modified samples were characterized for ion exchange capacity, morphology, and performance. The HPSU modified S-PVDF membrane shows good stability and ionic conductivity of 5.1 mS cm−1 at 80 °C and 100% RH for blends containing 20% HPSU, which is higher than the literature values for equivalent blend membranes using Nafion. SEM analysis of the blend membranes containing 15% or more HPSU shows the presence of spherical domains with a size range of 300–800 nm within the membranes, which are believed to be the HPSU-rich area. PMID:28348282

New Insights into Perfluorinated Sulfonic-Acid Ionomers

DOE PAGES

Kusoglu, Ahmet; Weber, Adam Z.

2017-01-23

In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers’ complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem frommore » correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films are presented. Throughout, the impact of PFSA chemistry and side-chain is also discussed to present a broader perspective.« less

Molecular deformation and stress-strain behavior of poly(bisphenol-A-diphenyl sulfone)

NASA Technical Reports Server (NTRS)

Hong, S.-D.; Chung, S. Y.; Fedors, R. F.

1983-01-01

The strain-birefringence response of poly(bisphenol-A-diphenyl sulfone) is found to be independent of temperature at temperatures below -100 C; at higher temperatures, the response becomes slightly dependent on temperature, with lower birefringence seen at higher temperatures. The stress-strain behavior and the stress-birefringence response both depend on temperature over the entire testing temperature range (-179 C to 150 C) studied; this dependence, however, is not pronounced. The evidence is seen as suggesting that the polymer molecules respond to deformation by undergoing conformational rearrangements; the mode of the molecular deformation remains unchanged for temperatures of -100 C or lower. At higher temperatures, the average length of the chain segments involved in the rearrangement increases. The stress-strain response is attributed mainly to chain orientation. The entropic contribution deriving from chain orientation at temperatures below -100 C is still substantial. The modest temperature dependence of the stress-strain response suggests that the energy barriers for the chain segments involved in the rearrangement are relatively low.

Spectroscopic optimization of all-solid-state electrochromic devices using PANI

NASA Astrophysics Data System (ADS)

Hugot-Le Goff, Anne; Bernard, Marie-Claude; Bich, Vu T.; Binh, Nguyen T.; Zeng, Wen

1997-12-01

The interesting optical properties of polyaniline (PANI) allowed its utilization in all solid-state electrochromic devices. Using a sulfonic acid polymer as solid electrolyte gave to PANI an unusual optical behavior leading to electrochromic properties very superior to the properties that it has in any liquid inorganic electrolyte. The improved conductivity of PANI doped with AMP-sulfonate is displayed by the presence of a free-carriers tail even at pH as high as 4.5. The free-carriers tail is studied using UV/vis/near IR spectroscopy, and the kinetics of coloration/bleaching are studied using Optical Multichannel Analysis in the 1.5 - 3 eV range. The modifications of the PANI optical features by solid-state doping are examined. The possibility to still improve the performances of these devices--in particular their rate of color change--by using `secondarily doped' PANI is investigated, which requires a preliminary spectrochemical analysis of PANI films doped with camphorsulfonic acid and treated in m-cresol during their electrochemical polarization.

Composite polymer electrolyte containing ionic liquid and functionalized polyhedral oligomeric silsesquioxanes for anhydrous PEM applications.

PubMed

Subianto, Surya; Mistry, Mayur K; Choudhury, Namita Roy; Dutta, Naba K; Knott, Robert

2009-06-01

A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporated into these membranes to provide proton conduction in the absence of water. Although the incorporation of an IL shows a plasticizing effect on the Nafion membrane, the S-POSS composite membrane with an IL shows a higher modulus at high temperatures compared to Nafion 117 and a Nafion-IL membrane, with significantly higher proton conductivity (5 mS/cm at 150 degrees C with 20% IL). This shows the ability of the multifunctional POSS and IL to work symbiotically to achieve the desirable proton conductivity and mechanical properties of such membranes by enhancing the ionic interaction within the material.

Determination of fenitrothion in water using a voltammetric sensor based on a polymer-modified glassy carbon electrode.

PubMed

Amare, Meareg; Abicho, Samuel; Admassie, Shimelis

2014-01-01

A glassy carbon electrode (GCE) modified with poly(4-amino-3-hydroxynaphthalene sulfonic acid) (poly-AHNSA) was used for the selective and sensitive determination of fenitrothion (FT) organophosphorus pesticide in water. The electrochemical behavior of FT at the bare GCE and the poly-AHNSA/GCE were compared using cyclic voltammetry. Enhanced peak current response and shift to a lower potential at the polymer-modified electrode indicated the electrocatalytic activity of the polymer film towards FT. Under optimized solution and method parameters, the adsorptive stripping square wave voltammetric reductive peak current of FT was linear to FT concentration in the range of 0.001 to 6.6 x 10(-6) M, and the LOD obtained (3delta/m) was 7.95 x 10(-10) M. Recoveries in the range 96-98% of spiked FT in tap water and reproducible results with RSD of 2.6% (n = 5) were obtained, indicating the potential applicability of the method for the determination of trace levels of FT in environmental samples.

Customization of copolymers to optimize selectivity and yield in polymer-driven antibody purification processes.

PubMed

Capito, Florian; Skudas, Romas; Stanislawski, Bernd; Kolmar, Harald

2013-01-01

This manuscript describes customization of copolymers to be used for polymer-driven protein purification in bioprocessing. To understand how copolymer customization can be used for fine-tuning, precipitation behavior was analyzed for five target antibodies (mAbs) and BSA as model impurity protein, at ionic strength similar to undiluted cell culture fluid. In contrast to the use of standardized homopolymers, customized copolymers, composed of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 4-(acryloylamino)benzoic acid (ABZ), exhibited antibody precipitation yields exceeding 90%. Additionally, copolymer average molecular weight (Mw ) was varied and its influence on precipitation yield and contaminant coprecipitation was investigated. Results revealed copolymer composition as the major driving force for precipitation selectivity, which was also dependent on protein hydrophobicity. By adjusting ABZ content and Mw of the precipitant for each of the mAbs, conditions were found that allowed for high precipitation yield and selectivity. These findings may open up new avenues for using polymers in antibody purification processes. © 2013 American Institute of Chemical Engineers.

Elaboration of m-cresol polyamide12/ polyaniline composite films for antistatic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezdour, D.; Tabellout, M.; Bardeau, J.-F

2013-12-16

The present work deals with the preparation of transparent antistatic films from an extreme dilution of an intrinsically conducting polymer (ICP) with not coloured polymers. Our approach is based on the chemical polymerization of a very thin layer of Polyaniline (PANI) around particles of an insulating polymer (PA12). Films were obtained by dissolving the synthesized core-shell particles in m-Cresol. The electric property and structure relationships were investigated by using dielectric relaxation spectroscopy, X-ray diffraction and micro-Raman spectroscopy. Composite films exhibited a well established dc conductivity over all the frequency range for 10 wt. % of PANI concentration related to themore » conductive properties of the PANI clusters. X-ray diffraction data show broader and lower intensity of PA12 peaks when increasing PANI content, probably due to the additional doping effect of m- cresol. The doping of PA12/PANI films with Dodecyl benzene sulfonic acid (DBSA) was unequivocally verified by Raman spectroscopy.« less

Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

PubMed Central

Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

2015-01-01

In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)–(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized. PMID:27877800

Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals.

PubMed

Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

2015-06-01

In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)-(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized.

Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

NASA Astrophysics Data System (ADS)

Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

2015-06-01

In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)-(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized.

Vanadium Requirements and Uptake Kinetics in the Dinitrogen-Fixing Bacterium Azotobacter vinelandii▿

PubMed Central

Bellenger, J. P.; Wichard, T.; Kraepiel, A. M. L.

2008-01-01

Vanadium is a cofactor in the alternative V-nitrogenase that is expressed by some N2-fixing bacteria when Mo is not available. We investigated the V requirements, the kinetics of V uptake, and the production of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium Azotobacter vinelandii. In strain CA11.70, a mutant that expresses only the V-nitrogenase, V concentrations in the medium between 10−8 and 10−6 M sustain maximum growth rates; they are limiting below this range and toxic above. A. vinelandii excretes in its growth medium micromolar concentrations of the catechol siderophores azotochelin and protochelin, which bind the vanadate oxoanion. The production of catechols increases when V concentrations become toxic. Short-term uptake experiments with the radioactive isotope 49V show that bacteria take up the V-catechol complexes through a regulated transport system(s), which shuts down at high V concentrations. The modulation of the excretion of catechols and of the uptake of the V-catechol complexes allows A. vinelandii to precisely manage its V homeostasis over a range of V concentrations, from limiting to toxic. PMID:18192412

Relation between the adsorbed quantity and the immersion enthalpy in catechol aqueous solutions on activated carbons.

PubMed

Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

2012-01-01

An activated carbon, Carbochem(TM)-PS230, was modified by chemical and thermal treatment in flow of H(2), in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pK(a). The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g(-1) for catechol aqueous solutions in a range of 20 at 1500 mg·L(-1).

Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

PubMed Central

Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

2012-01-01

An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1. PMID:22312237

Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide) based polyether-ester-sulfonate ionomers

NASA Astrophysics Data System (ADS)

Roach, David J.

Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though lithium hopping is about ten times slower than the segmental motion. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments. Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (T g) have been investigated using solid-state nuclear magnetic resonance (NMR). Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components and relative mobilities of the polymer backbone of a suite of. lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203-373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of cation content. Each of the main backbone components (PEO spacer and isophthalate groups) exhibit distinct motions, following the trends expected for motional characteristics based on earlier Quasi Elastic Neutron Scattering and 1H spin-lattice relaxation rate measurements. The temperature dependences of 13C linewidths were used to both qualitatively and quantitatively examine the effects of cation content on PEO mobility. Variable contact time 1H-13C CP-MAS experiments were used to further assess the motions of the polymer backbone on the microsecond timescale. The motion of the PEO spacer, determined from the rate of magnetization transfer from 1H to 13C nuclei, in all ionic samples becomes similar for T [special characters omitted] 1.1 Tg, indicating that the motions of the polymer backbones on the microsecond timescale become insensitive to ion interactions. These results compliment previous findings and present an improved picture of the dependence of backbone dynamics on cation type and density in these amorphous PEO-based ionomer systems. 7Li PFG NMR experiments provided measurements of the self-diffusion coefficients for Li+ cations in the PEO600-y Li ionomer series over a range of temperatures. When the Tg values are taken into account, the self-diffusion coefficients of Li+ in each sample follow a similar trendline, indicating that lithium diffusion is independent of ion concentration at any given reduced inverse temperature, Tg/T. Ion aggregation increases Tg and slows both lithium cation diffusion and displacement, but there is no further slowing beyond the Tg effect in the PEO600-y Li ionomers samples. The differences in activation energies obtained from diffusion measurements and relaxation times suggest that at least one additional barrier must be overcome for cations emerge from local hopping motion to macroscopic cation transpfort. Using the Nernst- Einstein equation lithium diffusion coefficients were also calculated from conductivity measurements. The differences between the diffusion measured by the two separate techniques indicate the presence of ion pairs. The activation energy of lithium diffusion was found to be nearly identical between the PFG NMR and conductivity, suggesting that the conductivity and ionic diffusion are related to the same ionic dynamics. As the ion content within the PEO600-y Li samples increases the relative concentration of nonconducting ion pairs decrease. Also an increase in temperature causes a fraction of ion pairs to thermally dissociate into positive triple ions.

High-Temperature Shape Memory Polymers

NASA Technical Reports Server (NTRS)

Yoonessi, Mitra; Weiss, Robert A.

2012-01-01

physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing radiation ( radiation, neutrons), or by chemical crosslinking to form a covalent permanent network. With respect to other shape memory polymers, this invention is novel in that it describes the use of a thermoplastic composition that can be thermally molded or solution-cast into complex "permanent" shapes, and then reheated or redissolved and recast from solution to prepare another shape. It is also unique in that the shape memory behavior is provided by a non-polymer additive.

Application of Novel Anion-Exchange Blend Membranes (AEBMs) to Vanadium Redox Flow Batteries.

PubMed

Cho, Hyeongrae; Krieg, Henning M; Kerres, Jochen A

2018-06-19

Both cation-exchange membranes and anion-exchange membranes are used as ion conducting membranes in vanadium redox flow batteries (VRFBs). Anion-exchange membranes (AEMs) are applied in vanadium redox flow batteries due to the high blocking property of vanadium ions via the Donnan exclusion effect. In this study, novel anion-exchange blend membranes (AEBMs) were prepared, characterized, and applied in VRFBs. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide), poly[(1-(4,4′-diphenylether)-5-oxybenzimidazole)-benzimidazole] (PBI-OO) and sulfonated polyether sulfone polymer were combined to prepare 3-component AEBMs with 1,2,4,5-tetramethylimidazole (TMIm) for quaternization. 3-component AEBMs showed significantly enhanced chemical and mechanical properties compared with those of 2-component AEBMs, resulting in an improved performance in VRFBs. The compositions of the anion-exchange polymers in 3-component AEBMs were systematically varied to optimize the AEBMs for the redox-flow battery application. While the 3-component AEBMs showed comparable efficiencies with Nafion ® 212 membranes, they displayed improved vanadium ions cross-over as was confirmed by open circuit voltage tests and capacity fade tests conducted in VRFBs. In addition, one of the synthesized 3-component AEBM had a superior coulombic efficiency and capacity retention in a charging⁻discharging test over 300 cycles at a current density of 40 mA/cm². It can thus be concluded that 3-component AEBMs are promising candidates for long-term operation in VRFBs.

3D conductive nanocomposite scaffold for bone tissue engineering

PubMed Central

Shahini, Aref; Yazdimamaghani, Mostafa; Walker, Kenneth J; Eastman, Margaret A; Hatami-Marbini, Hamed; Smith, Brenda J; Ricci, John L; Madihally, Sundar V; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

Bone healing can be significantly expedited by applying electrical stimuli in the injured region. Therefore, a three-dimensional (3D) ceramic conductive tissue engineering scaffold for large bone defects that can locally deliver the electrical stimuli is highly desired. In the present study, 3D conductive scaffolds were prepared by employing a biocompatible conductive polymer, ie, poly(3,4-ethylenedioxythiophene) poly(4-styrene sulfonate) (PEDOT:PSS), in the optimized nanocomposite of gelatin and bioactive glass. For in vitro analysis, adult human mesenchymal stem cells were seeded in the scaffolds. Material characterizations using hydrogen-1 nuclear magnetic resonance, in vitro degradation, as well as thermal and mechanical analysis showed that incorporation of PEDOT:PSS increased the physiochemical stability of the composite, resulting in improved mechanical properties and biodegradation resistance. The outcomes indicate that PEDOT:PSS and polypeptide chains have close interaction, most likely by forming salt bridges between arginine side chains and sulfonate groups. The morphology of the scaffolds and cultured human mesenchymal stem cells were observed and analyzed via scanning electron microscope, micro-computed tomography, and confocal fluorescent microscope. Increasing the concentration of the conductive polymer in the scaffold enhanced the cell viability, indicating the improved microstructure of the scaffolds or boosted electrical signaling among cells. These results show that these conductive scaffolds are not only structurally more favorable for bone tissue engineering, but also can be a step forward in combining the tissue engineering techniques with the method of enhancing the bone healing by electrical stimuli. PMID:24399874

Selectivity of Direct Methanol Fuel Cell Membranes.

PubMed

Aricò, Antonino S; Sebastian, David; Schuster, Michael; Bauer, Bernd; D'Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

2015-11-24

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion(®) were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate-PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion(®) 115-based MEA (77 mW·cm(-2) vs. 64 mW·cm(-2)). This result was due to a lower methanol crossover (47 mA·cm(-2) equivalent current density for s-PEEK vs. 120 mA·cm(-2) for Nafion(®) 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm² for s-PEEK vs. 0.22 Ohm cm² for Nafion(®) 115).

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

PubMed Central

Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beon; Bae, Jin-Hyuk; Kang, Shin-Won

2017-01-01

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C61-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains. PMID:28338088

Potential of Wood-Rotting Fungi to Attack Polystyrene Sulfonate and Its Depolymerisation by Gloeophyllum trabeum via Hydroquinone-Driven Fenton Chemistry

PubMed Central

Krueger, Martin C.; Hofmann, Ulrike; Moeder, Monika; Schlosser, Dietmar

2015-01-01

Synthetic polymers often pose environmental hazards due to low biodegradation rates and resulting accumulation. In this study, a selection of wood-rotting fungi representing different lignocellulose decay types was screened for oxidative biodegradation of the polymer polystyrene sulfonate (PSS). Brown-rot basidiomycetes showed PSS depolymerisation of up to 50 % reduction in number-average molecular mass (Mn) within 20 days. In-depth investigations with the most efficient depolymeriser, a Gloeophyllum trabeum strain, pointed at extracellular hydroquinone-driven Fenton chemistry responsible for depolymerisation. Detection of hydroxyl radicals present in the culture supernatants showed good compliance with depolymerisation over the time course of PSS degradation. 2,5-Dimethoxy-1,4-hydroquinone (2,5-DMHQ), which was detected in supernatants of active cultures via liquid chromatography and mass spectrometry, was demonstrated to drive the Fenton processes in G. trabeum cultures. Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ. Furthermore, 2,5-DMHQ could initiate the Fenton's reagent-mediated PSS depolymerisation in cell-free systems. In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes. Detailed investigations with laccase from Trametes versicolor revealed that only in presence of certain redox mediators limited PSS depolymerisation occurred. Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants. PMID:26147966

Selectivity of Direct Methanol Fuel Cell Membranes

PubMed Central

Aricò, Antonino S.; Sebastian, David; Schuster, Michael; Bauer, Bernd; D’Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

2015-01-01

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion® were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate–PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion® 115-based MEA (77 mW·cm−2 vs. 64 mW·cm−2). This result was due to a lower methanol crossover (47 mA·cm−2 equivalent current density for s-PEEK vs. 120 mA·cm−2 for Nafion® 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm2 for s-PEEK vs. 0.22 Ohm cm2 for Nafion® 115). PMID:26610582

Ordered adsorption of coagulation factor XII on negatively charged polymer surfaces probed by sum frequency generation vibrational spectroscopy.

PubMed

Chen, Xiaoyun; Wang, Jie; Paszti, Zoltan; Wang, Fulin; Schrauben, Joel N; Tarabara, Volodymyr V; Schmaier, Alvin H; Chen, Zhan

2007-05-01

Electrostatic interactions between negatively charged polymer surfaces and factor XII (FXII), a blood coagulation factor, were investigated by sum frequency generation (SFG) vibrational spectroscopy, supplemented by several analytical techniques including attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), quartz crystal microbalance (QCM), zeta-potential measurement, and chromogenic assay. A series of sulfonated polystyrenes (sPS) with different sulfonation levels were synthesized as model surfaces with different surface charge densities. SFG spectra collected from FXII adsorbed onto PS and sPS surfaces with different surface charge densities showed remarkable differences in spectral features and especially in spectral intensity. Chromogenic assay experiments showed that highly charged sPS surfaces induced FXII autoactivation. ATR-FTIR and QCM results indicated that adsorption amounts on the PS and sPS surfaces were similar even though the surface charge densities were different. No significant conformational change was observed from FXII adsorbed onto surfaces studied. Using theoretical calculations, the possible contribution from the third-order nonlinear optical effect induced by the surface electric field was evaluated, and it was found to be unable to yield the SFG signal enhancement observed. Therefore it was concluded that the adsorbed FXII orientation and ordering were the main reasons for the remarkable SFG amide I signal increase on sPS surfaces. These investigations indicate that negatively charged surfaces facilitate or induce FXII autoactivation on the molecular level by imposing specific orientation and ordering on the adsorbed protein molecules.

3D conductive nanocomposite scaffold for bone tissue engineering.

PubMed

Shahini, Aref; Yazdimamaghani, Mostafa; Walker, Kenneth J; Eastman, Margaret A; Hatami-Marbini, Hamed; Smith, Brenda J; Ricci, John L; Madihally, Sundar V; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

Bone healing can be significantly expedited by applying electrical stimuli in the injured region. Therefore, a three-dimensional (3D) ceramic conductive tissue engineering scaffold for large bone defects that can locally deliver the electrical stimuli is highly desired. In the present study, 3D conductive scaffolds were prepared by employing a biocompatible conductive polymer, ie, poly(3,4-ethylenedioxythiophene) poly(4-styrene sulfonate) (PEDOT:PSS), in the optimized nanocomposite of gelatin and bioactive glass. For in vitro analysis, adult human mesenchymal stem cells were seeded in the scaffolds. Material characterizations using hydrogen-1 nuclear magnetic resonance, in vitro degradation, as well as thermal and mechanical analysis showed that incorporation of PEDOT:PSS increased the physiochemical stability of the composite, resulting in improved mechanical properties and biodegradation resistance. The outcomes indicate that PEDOT:PSS and polypeptide chains have close interaction, most likely by forming salt bridges between arginine side chains and sulfonate groups. The morphology of the scaffolds and cultured human mesenchymal stem cells were observed and analyzed via scanning electron microscope, micro-computed tomography, and confocal fluorescent microscope. Increasing the concentration of the conductive polymer in the scaffold enhanced the cell viability, indicating the improved microstructure of the scaffolds or boosted electrical signaling among cells. These results show that these conductive scaffolds are not only structurally more favorable for bone tissue engineering, but also can be a step forward in combining the tissue engineering techniques with the method of enhancing the bone healing by electrical stimuli.

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

NASA Astrophysics Data System (ADS)

Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beon; Bae, Jin-Hyuk; Kang, Shin-Won

2017-03-01

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C61-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains.

A biomimetic approach to enhancing interfacial interactions: polydopamine-coated clay as reinforcement for epoxy resin.

PubMed

Yang, Liping; Phua, Si Lei; Teo, Jun Kai Herman; Toh, Cher Ling; Lau, Soo Khim; Ma, Jan; Lu, Xuehong

2011-08-01

A facile biomimetic method was developed to enhance the interfacial interaction in polymer-layered silicate nanocomposites. By mimicking mussel adhesive proteins, a monolayer of polydopamine was constructed on clay surface by a controllable coating method. The modified clay (D-clay) was incorporated into an epoxy resin, it is found that the strong interfacial interactions brought by the polydopamine benefits not only the dispersion of the D-clay in the epoxy but also the effective interfacial stress transfer, leading to greatly improved thermomechanical properties at very low inorganic loadings. Rheological and infrared spectroscopic studies show that the interfacial interactions between the D-clay and epoxy are dominated by the hydrogen bonds between the catechol-enriched polydopamine and the epoxy.

Mussel-mimetic, bioadhesive polymers from plant-derived materials.

PubMed

Hiraishi, Noriko; Kaneko, Daisaku; Taira, Shu; Wang, Siqian; Otsuki, Masayuki; Tagami, Junji

2015-02-01

Mussel-mimetic, bioadhesive polymers are synthesized from plant-derived sources. The strong adhesive action is caused by interactions between the catechol groups at the end of the polymer terminal chains and the substrate surface. Here, we present a preliminary study of the adhesion properties and a discussion of the adhesion mechanism. Two bioadhesive polymers were synthesized from natural plant-derived monomers by the transesterification of: (a) caffeic acid (3,4-dihydroxycinnamic acid; DHCA) and p-coumaric acid (4-hydroxycinnamic acid; 4HCA) to produce poly(DHCA-co-4HCA); and (b) 4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(3-hydroxyphenyl) propionic acid (3HPPA) to produce poly(DHHCA-co-3HPPA). Thermoplastic poly(DHCA-co-4HCA) or poly(DHHCA-co-3HPPA) was placed between glass, carbon, steel, or bovine dentin substrates, and a lap shear adhesion test was conducted to compare them using conventional cyanoacrylate glue and epoxy resin. The greatest adhesion for all tested substrates was exhibited by poly(DHHCA-co-3HPPA), followed by epoxy resin adhesive, poly(DHCA-co-4HCA), and cyanoacrylate adhesive. The adhesive strength of poly(DHHCA-co-3HPPA) was greater than 25.6 MPa for glass, 29.6 MPa for carbon, 15.7 MPa for steel, and 16.3 MPA for bovine dentin. The adhesion of poly(DHHCA-co-3HPPA) might be the strongest reported for a mussel-mimic adhesive system, and could be a feasible alternative to petroleum adhesives. © 2013 Wiley Publishing Asia Pty Ltd.

Mussel-inspired polydopamine biopolymer decorated with magnetic nanoparticles for multiple pollutants removal.

PubMed

Zhang, Shengxiao; Zhang, Yuanyuan; Bi, Guoming; Liu, Junshen; Wang, Zhigang; Xu, Qiang; Xu, Hui; Li, Xiaoyan

2014-04-15

The polydopamine polymer decorated with magnetic nanoparticles (Fe3O4/PDA) was synthesized and applied for removal of multiple pollutants. The resulted Fe3O4/PDA was characterized with elemental analysis, thermo-gravimetric analyses, vibrating sample magnetometer, high resolution transmission electron microscope, Fourier transform infrared spectra, and X-ray photoelectron spectroscopy. The self-polymerization of dopamine could be completed within 8h, and Fe3O4 nanoparticles were embedded into PDA polymer. Superparamagnetism and large saturation magnetization facilitated collection of sorbents with a magnet. Based on the catechol and amine groups, the PDA polymer provided multiple interactions to combine with pollutants. To investigate the adsorption ability of Fe3O4/PDA, heavy metal ions and dyes were selected as target pollutants. The adsorption of pollutants was pH dependent due to the variation of surface charges at different solution pH. The removal efficiencies of cation pollutants enhanced with solution pH increasing, and that of anion pollutant was just the opposite. Under the optimal solution pH, the maximum adsorption capacity calculated from Langmuir adsorption isotherm for methylene blue, tartrazine, Cu(2+), Ag(+), and Hg(2+) were 204.1, 100.0, 112.9, 259.1, and 467.3 mg g(-1), respectively. The Fe3O4/PDA shows great potential for multiple pollutants removal, and this study is the first application of PDA polymer in environmental remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

Poly(p-Phenylene Sulfonic Acids). PEMs with frozen-in free volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Litt, Morton

2016-01-21

Early work with rigid rod aromatic polyelectrolytes implied that steric hindrance in packing of the rigid rods left unoccupied volumes that could absorb and hold water molecules strongly. We called this “frozen in free volume). It is illustrated and contrasted with the packing of flexible backbone polyelectrolytes (Reference 5 of this report). This was quantified for poly(biphenylene disulfonic acid) (PBDSA) and poly(phenylene disulfonic acid) (PPDSA). We found that PPDSA held three water molecules per acid group down to 11% relative humidity (RH) and had very high conductivity even at these low RHs. (Reference 1 of report.) The frozen-in free volumemore » was calculated to be equivalent to a λ of 3.5. The work reported below concentrated on studying these polymers and their copolymers with biphenylene disulfonic acid. As expected, the polyelectrolytes are water soluble. Several approaches towards making water stable films were studied. Grafting alkyl benzene substituents on sulfonic acid groups had worked for PBPDSA (1) so it was tried with PPDSA and a 20%/80% copolymer of BPDSA and PDSA (B20P80). T-butyl, n-octyl and n-dodecyl benzene were grafted. Good films could be made. Water absorption and conductivity were studied as a function of RH and temperature (Reference 2). When less than 20% of the sulfonic acid groups were grafted, conductivity was much higher than that of Nafion NR212 at all RHs. At low graft levels, conductivity was ten times higher. Mechanical properties and swelling were acceptable below 90% RH. However, all the films were unstable in water and slowly disintegrated. The proposed explanation was that the molecules formed nano-aggregates in solution held together by hydrophobic bonding. Their cast films disintegrated when placed in water since hydrophobic bonding between the nano-aggregates was poor. We then shifted to crosslinking as a method to produce water stable films (References 3 and 4). Biphenyl could easily be reacted with the polymer, generating biphenyl sulfone grafts. Films were cast and then crosslinked by heating to 210°C for at least one hour. There was no loss of acid groups even after heating at 225°C for two hours. PPDSA and B20P80 polymers were grafted and crosslinked. Conductivity and water absorption were measured on polymers with grafting degrees from 3 to 16%. As before they all had much higher conductivity than Nafion NR212. One sample was tested as a fuel cell membrane. Unfortunately it tore; the tear was mended with a 3M ionomer. There was some hydrogen leakage. However, the current at a given voltage was about 95% that of a Nafion NR212 membrane over the whole useful range. Considering that this was the first test for such a system, this is remarkable performance. A mechanically better membrane was tested at the end of the grant period. This did not have tears or micro cracks (Reference 5). Testing confirmed earlier data (Sergio Granados-Focil, Ph. D. Thesis, CWRU. 2006) that such very polar membranes were excellent barriers to hydrogen diffusion. Standard measurements showed no hydrogen leakage. This was confirmed by open circuit voltage measurements. They were higher than those of the Nafion NR212 cells. Again the single cell performance was about 95% that of the Nafion SR212 cell over the whole range. These films show great promise. They are very stable and perform very well at very low humidity. They should be able to outperform the present cells with relatively little further development. A second project is reported fully in the final report since it was not published. Its goal was to make membranes with high conductivity and good mechanical strength that would have a constant volume at all RHs. We made large planar 2-D polymers containing 1.5 nm holes lined with sulfonic acid groups. These should hold water very strongly. The largest made was calculated to have a number average diameter of 29 nm. It was expected that when they were cast, they would aggregate and create channels for proton conduction. However, they were so large that they aggregated in solution during preparation. Measurements showed that the aggregates developed long channels. This was demonstrated and is reported. Unfortunately, the aggregates could not be cast with the channels perpendicular to the film plane. If methods are developed to keep the molecules in solution until they are cast, their planes should be parallel and the channels perpendicular to the film direction. They could be very interesting and perhaps important materials.« less

Features of the supercritical CO2-assisted immobilization of fluorinated tetraphenylporphyrins into tetrafluoroethylene copolymers

NASA Astrophysics Data System (ADS)

Shershnev, I. V.; Cherkasova, A. V.; Kopylov, A. S.; Glagolev, N. N.; Bragina, N. A.; Solov'eva, A. B.

2017-07-01

The immobilization of fluorinated tetraphenylporphyrins (FTPPs) into tetrafluoroethylene copolymers (fluoroplast F-42 and MF-4SK, a perfluorinated sulfonic acid cation exchanger in H+-form) is conducted in supercritical CO2 (scCO2). The effects the conditions of immobilization (the temperature and pressure of scCO2, reaction time, and the addition of cosolvents) and the structure of the carrier polymer have on the content of porphyrin in these polymers is studied. The porphyrin-loaded polymer systems are shown to exhibit photosensitizing activity in anthracene and cholesterol oxidation in scCO2. Under conditions of photocatalysis, chemical and functional stability is a feature of only MF-4SK polymer systems; this is attributed to the formation of protonated forms of the porphyrins and their interaction with SO3 --groups of the polymer (an ion exchange process), which prevents leaching of the FTPP from the polymer matrix. The photocatalytic process actually occurs inside the matrix of the perfluorinated copolymer, with the protonated form of the porphyrin acting as a photosensitizer. The rate constant of anthracene photooxidation in the presence of FTPP-loaded MF-4SK films in scCO2 is found to pass through a maximum as a function of the porphyrin content and the polymer film thickness. The use of such catalytic systems for cholesterol photooxidation in scCO2 is shown to produce a virtual monoproduct (yield, 10%): 6-formyl-B-norcholestane-3,5-diol, a compound with high biological activity.

Efficient detection of hazardous catechol and hydroquinone with MOF-rGO modified carbon paste electrode.

PubMed

Wang, Hailong; Hu, Quanqin; Meng, Yuan; Jin, Zier; Fang, Zilin; Fu, Qinrui; Gao, Wenhua; Xu, Liang; Song, Yibing; Lu, Fushen

2018-02-19

Reduced graphite oxide (rGO) was incorporated into a metal organic framework (MOF) MIL-101(Cr) for the modification of carbon paste electrode. Taking advantages of the large surface area of MOF and the electrical conductivity of rGO, the resulted electrodes exhibited high sensitivity and reliability in the simultaneous electrochemical identification and quantification of catechol (CC) and hydroquinone (HQ). Specifically, in the mixture solution of catechol and hydroquinone (constant concentration of an analyte), the linear response ranges for catechol and hydroquinone were 10-1400 μM and 4-1000 μM, and detection limits were 4 μM and 0.66 μM (S/N = 3) for individual catechol and hydroquinone, respectively. Therefore, the relatively easy fabrication of modified CPE and its fascinating reliability towards HQ and CC detection may simulate more research interest in the applications of MIL-101(Cr)-rGO composites for electrochemical sensors. Copyright © 2018 Elsevier B.V. All rights reserved.

Processable Conducting Polyaniline, Carbon Nanotubes, Graphene and Their Composites

NASA Astrophysics Data System (ADS)

Wang, Kan

Good processability is often required for applications of conducting materials like polyaniline (PANI), carbon nanotubes (CNTs) and graphene. This can be achieved by either physical stabilization or chemical functionalization. Functionalization usually expands the possible applications for the conducting materials depending on the properties of the functional groups. Processable conducting materials can also be combined with other co-dissolving materials to prepare composites with desired chemical and physical properties. Polyanilines (PANI) doped with dodecylbenzenesulfonic acid (DBSA) are soluble in many organic solvents such as chloroform and toluene. Single wall carbon nanotubes (SWCNTs) can be dispersed into PANI/DBSA to form homogeneous solutions. PANI/DBSA functions as a conducting surfactant for SWCNTs. The mixture can be combined with two-parts polyurethanes that co-dissolve in the organic solvent to produce conducting polymer composites. The composite mixtures can be applied onto various substrates by simple spray-on methods to obtain transparent and conducting coatings. Graphene, a single layer of graphite, has drawn intense interest for its unique properties. Processable graphene has been produced in N-methyl-2-pyrrolidone (NMP) by a one-step solvothermal reduction of graphite oxide without the aid of any reducing reagent and/or surfactant. The as-synthesized graphene disperses well in a variety of organic solvents such as dimethylsulfoxide (DMSO), ethanol and tetrahydrogenfuran (THF). The conductivity of solvothermal reduced graphite oxide is comparable to hydrazine reduced graphite oxide. Attempts were made to create intrinsically conducting glue comparable to mussel adhesive protiens using polyaniline and graphene. Mussels can attach to a variety of substrates under water. Catechol residue in 3,4-dihydroxyphenylalanine (L-DOPA) is the key to the wet adhesion. Tyrosine and phosphoserine with primary alkyl amine groups also participate in adhesion. A novel water soluble synthetic mussel adhesive containing both catechol and amine groups are synthesized in a simple approach. A polyallylamine backbone is used to take the place of the polyamide chain. Catechol is appended to the backbone as the key cross-linking group. Compared to polyallyamine, poly[N-(3,4- dihydroxybenzylidene)allylamine] exhibits good adhesion under alkaline water due to moderate cross-linking. When exposed to cross-linkers, this synthetic mussel adhesive can form a hydrogel at a very low concentration. Various methods were tried to attach catechol group onto polyaniline and graphene to make synthetic conductive mussel adhesive. Although the chemistry proved to be successful, the material doesn't show great adhesion to selected substrates probably due the nature of the backbone and difficulties associated with its processability

Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

NASA Astrophysics Data System (ADS)

Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

2015-12-01

The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

Stability of self-assembled polymer films investigated by optical laser reflectometry.

PubMed

Dejeu, Jérôme; Diziain, Séverine; Dange, Catherine; Membrey, François; Charraut, Daniel; Foissy, Alain

2008-04-01

We studied the influence of post-treatment rinsing after the formation of self-assembled polyelectrolyte films made with the weak base poly(allylamine hydrochloride) (PAH) and the strong acid poly(styrene sulfonate) (PSS). The stability of the film was studied using optical fixed-angle laser reflectometry to measure the release of polymeric material and AFM experiments to reveal the change of morphology and thickness. We found that the polymer films were stable upon rinsing when the pH was the same in the solution as that used in the buildup (pH 9). The films released most of the polymeric material when rinsed at higher pH values, but a layer remained that corresponded to a PAH monolayer directly bound with the silica surface. Films containing at least four bilayers were stable upon rinsing at lower pH values, but the stability of thinner films depended on the type of the last polymer deposited. They were stable in the case of PSS as an outermost deposit, but they released a large part of their material in the case of PAH. The stability results were determined using a simple model of the step-by-step assembly of the polymer film described formerly.

Nonlinear optical moiety-doped polymers with improved optical properties for photonic devices

NASA Astrophysics Data System (ADS)

Lee, Myung-Hyun; Kim, Hwan K.; Kim, Hye-Young; Lee, Hyuek J.; Kang, K. H.; Won, Yong Hyub; Jeon, Eunsuk S.; Wu, Jeong W.

1994-05-01

An electro-optic polymer guest-host system has been constructed and demonstrated. The polymer host is a polyimide (PIQ2200) and the guest chromophores are dimethyl (or diethyl) amino alkyl sulfone stilbenes. The alkylated-NLO moieties as guest chromophores have been modified, yielding new alkylated-NLO moieties. The higher content of alkylated-NLO moieties, compared to unmodified NLO moieties, was doped into a polyimide host system due to the improved solubility of new alkylated-NLO moieties. To the 40 wt%, the new alkylated- NLO moiety has been completely dissolved in the preliminary experiment, leading to the increase of refractive index by 0.0016. These polyimide-based guest-host systems exhibited a significant improvement in the thermal stability at high temperatures exceeding 250 degree(s)C. The electro-optic coefficient reported in the present study is 13 pm/V for the 40 wt% DASS-6- doped polymer system poled at the 135 V/micrometers . However, further increase up to 25 pm/V may easily be achieved by increasing the amount of guest moieties and/or the intensity of the poling field. This work presents new materials for photonic switching devices with low operating voltage.

Role of catechol in the radical reduction of B-alkylcatecholboranes in presence of methanol.

PubMed

Povie, Guillaume; Villa, Giorgio; Ford, Leigh; Pozzi, Davide; Schiesser, Carl H; Renaud, Philippe

2010-02-07

Mechanistic investigations on the previously reported reduction of B-alkylcatecholboranes in the presence of methanol led to the disclosure of a new mechanism involving catechol as a reducing agent. More than just revising the mechanism of this reaction, we disclose here the surprising role of catechol, a chain breaking antioxidant, which becomes a source of hydrogen atoms in an efficient radical chain process.

New metabolic pathway for degradation of 2-nitrobenzoate by Arthrobacter sp. SPG

PubMed Central

Arora, Pankaj K.; Sharma, Ashutosh

2015-01-01

Arthrobacter sp. SPG utilized 2-nitrobenzoate as its sole source of carbon and energy and degraded it with accumulation of stoichiometric amounts of nitrite ions. Salicylate and catechol were detected as metabolites of the 2-nitrobenzoate degradation using high performance liquid chromatography and gas chromatography–mass spectrometry. Enzyme activities for 2-nitrobenzoate-2-monooxygenase, salicylate hydroxylase, and catechol-1,2-dioxygenase were detected in the crude extracts of the 2-nitrobenzoate-induced cells of strain SPG. The 2-nitrobenzoate-monooxygenase activity resulted in formation of salicylate and nitrite from 2-nitrobenzoate, whereas salicylate hydroxylase catalyzed the conversion of salicylate to catechol. The ring-cleaving enzyme, catechol-1,2-dioxygenase cleaved catechol to cis,cis-muconic acid. Cells of strain SPG were able to degrade 2-nitrobenzoate in sterile as well as non-sterile soil microcosms. The results of microcosm studies showed that strain SPG degraded more than 90% of 2-nitrobenzoate within 10–12 days. This study clearly shows that Arthrobacter sp. SPG degraded 2-nitrobenzoate via a new pathway with formation of salicylate and catechol as metabolites. Arthrobacter sp. SPG may be used for bioremediation of 2-nitrobenzoate-contaminated sites due to its ability to degrade 2-nitrobenzoate in soil. PMID:26082768

Influence of Brij58 on the Characteristic and Performance of PES Membrane for Water Treatment Process

NASA Astrophysics Data System (ADS)

Mukramah; Syawaliah; Mulyati, S.; Arahman, N.

2017-03-01

This study proposes a modification of polyether sulfone (PES) membrane by blending the polymer with a hydrophilic additive of Brij-58. Flat-sheet PES membrane was prepared through a non-solvent induced phase separation (NIPS) method using dimethylformamide (DMF) as a solvent. PES membrane was modified by adding Brij-58 into dope solution at a different concentration, i.e 1, 3, 5, 7, and 10 wt %. The fabricated membranes were characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red (FTIR) spectroscopy. Filtration performance of membrane was analyzed by using a dead-end module. It is found that the addition of a small amount of Brij into polymer solution brought about the increase of water flux. FT-IR investigation showed that the additive exist on the surface of a blended membrane.

NMR study on mechanisms of ionic polymer-metal composites deformation with water content

NASA Astrophysics Data System (ADS)

Zhu, Zicai; Chen, Hualing; Wang, Yongquan; Luo, Bin; Chang, Longfei; Li, Bo; Chen, Luping

2011-10-01

Ionic polymer-metal composites (IPMCs) exhibit a large dynamic bending deformation under exterior electric field. The states and proportions of water within the IPMCs have great effect on the IPMCs deformation properties. This letter investigates the influence of the proportion changes of different types of water on the deformation, which may disclose the working mechanisms of the IPMCs. We give a deformation trend of IPMCs with the reduction of water content firstly. Then by the method of nuclear magnetic resonance, various water types (water bonded to sulfonates, loosely bound water and free water) of IPMCs and their proportions are investigated in the drying process which corresponds to their different deformation states. It is obtained that the deformation properties of IPMCs depend strongly on their water content and the excess free water is responsible for the relaxation deformation.

Acid-functionalized nanoparticles for biomass hydrolysis

NASA Astrophysics Data System (ADS)

Pena Duque, Leidy Eugenia

Cellulosic ethanol is a renewable source of energy. Lignocellulosic biomass is a complex material composed mainly of cellulose, hemicellulose, and lignin. Biomass pretreatment is a required step to make sugar polymers liable to hydrolysis. Mineral acids are commonly used for biomass pretreatment. Using acid catalysts that can be recovered and reused could make the process economically more attractive. The overall goal of this dissertation is the development of a recyclable nanocatalyst for the hydrolysis of biomass sugars. Cobalt iron oxide nanoparticles (CoFe2O4) were synthesized to provide a magnetic core that could be separated from reaction using a magnetic field and modified to carry acid functional groups. X-ray diffraction (XRD) confirmed the crystal structure was that of cobalt spinel ferrite. CoFe2O4 were covered with silica which served as linker for the acid functions. Silica-coated nanoparticles were functionalized with three different acid functions: perfluoropropyl-sulfonic acid, carboxylic acid, and propyl-sulfonic acid. Transmission electron microscope (TEM) images were analyzed to obtain particle size distributions of the nanoparticles. Total carbon, nitrogen, and sulfur were quantified using an elemental analyzer. Fourier transform infra-red spectra confirmed the presence of sulfonic and carboxylic acid functions and ion-exchange titrations accounted for the total amount of catalytic acid sites per nanoparticle mass. These nanoparticles were evaluated for their performance to hydrolyze the beta-1,4 glycosidic bond of the cellobiose molecule. Propyl-sulfonic (PS) and perfluoropropyl-sulfonic (PFS) acid functionalized nanoparticles catalyzed the hydrolysis of cellobiose significantly better than the control. PS and PFS were also evaluated for their capacity to solubilize wheat straw hemicelluloses and performed better than the control. Although PFS nanoparticles were stronger acid catalysts, the acid functions leached out of the nanoparticle during the catalytic reactions. PS nanoparticles were further evaluated for the pretreatment of corn stover in order to increase digestibility of the biomass. The pretreatment was carried out at three different catalyst load and temperature levels. At 180°C, the total glucose yield was linearly correlated to the catalyst load. A maximum glucose yield of 90% and 58% of the hemicellulose sugars were obtained at this temperature.

Counterion adsorption and desorption rate of a charged macromolecule

NASA Astrophysics Data System (ADS)

Shi, Yu; Yang, Jingfa; Zhao, Jiang

The rate constant of counterion adsorption to and desorption from a synthetic polyelectrolyte, polystyrene sulfonate (PSS-), is measured in aqueous solution by single molecule fluorescence spectroscopy. The results show that both adsorption and desorption rate of counterions have strong dependence on polymer concentration, salt concentration as well as the molecular weight of polyelectrolytes. The results clearly demonstrate that the contribution of electrostatic interaction and the translational entropy to the distribution of counterions of a polyelectrolyte molecule. The information is helpful to the understanding of polyelectrolyte physics. National Natural Science Foundation of China.

Significant vertical phase separation in solvent-vapor-annealed poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) composite films leading to better conductivity and work function for high-performance indium tin oxide-free optoelectronics.

PubMed

Yeo, Jun-Seok; Yun, Jin-Mun; Kim, Dong-Yu; Park, Sungjun; Kim, Seok-Soon; Yoon, Myung-Han; Kim, Tae-Wook; Na, Seok-In

2012-05-01

In the present study, a novel polar-solvent vapor annealing (PSVA) was used to induce a significant structural rearrangement in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films in order to improve their electrical conductivity and work function. The effects of polar-solvent vapor annealing on PEDOT:PSS were systematically compared with those of a conventional solvent additive method (SAM) and investigated in detail by analyzing the changes in conductivity, morphology, top and bottom surface composition, conformational PEDOT chains, and work function. The results confirmed that PSVA induces significant phase separation between excess PSS and PEDOT chains and a spontaneous formation of a highly enriched PSS layer on the top surface of the PEDOT:PSS polymer blend, which in turn leads to better 3-dimensional connections between the conducting PEDOT chains and higher work function. The resultant PSVA-treated PEDOT:PSS anode films exhibited a significantly enhanced conductivity of up to 1057 S cm(-1) and a tunable high work function of up to 5.35 eV. The PSVA-treated PEDOT:PSS films were employed as transparent anodes in polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs). The cell performances of organic optoelectronic devices with the PSVA-treated PEDOT:PSS anodes were further improved due to the significant vertical phase separation and the self-organized PSS top surface in PSVA-treated PEDOT:PSS films, which can increase the anode conductivity and work function and allow the direct formation of a functional buffer layer between the active layer and the polymeric electrode. The results of the present study will allow better use and understanding of polymeric-blend materials and will further advance the realization of high-performance indium tin oxide (ITO)-free organic electronics.

Polystyrene bound oxidovanadium(IV) and dioxidovanadium(V) complexes of histamine derived ligand for the oxidation of methyl phenyl sulfide, diphenyl sulfide and benzoin.

PubMed

Maurya, Mannar R; Arya, Aarti; Kumar, Amit; Pessoa, João Costa

2009-03-28

Ligand Hsal-his (I) derived from salicylaldehyde and histamine has been covalently bound to chloromethylated polystyrene cross-linked with 5% divinylbenzene. Upon treatment with [VO(acac)(2)] in DMF, the polystyrene-bound ligand (abbreviated as PS-Hsal-his, II) gave the stable polystyrene-bound oxidovanadium(iv) complex PS-[V(IV)O(sal-his)(acac)] , which upon oxidation yielded the dioxidovanadium(v) PS-[V(V)O(2)(sal-his)] complex. The corresponding non polymer-bound complexes [V(IV)O(sal-his)(acac)] and [V(V)O(2)(sal-his)] have also been obtained. These complexes have been characterised by IR, electronic, (51)V NMR and EPR spectral studies, and thermal as well as scanning electron micrograph studies. Complexes and have been used as a catalyst for the oxidation of methyl phenyl sulfide, diphenyl sulfide and benzoin with 30% H(2)O(2) as oxidant. Under the optimised reaction conditions, a maximum of 93.8% conversion of methyl phenyl sulfide with 63.7% selectivity towards methyl phenyl sulfoxide and 36.3% towards methyl phenyl sulfone has been achieved in 2 h with 2 . Under similar conditions, diphenyl sulfide gave 83.4% conversion where selectivity of reaction products varied in the order: diphenyl sulfoxide (71.8%) > diphenyl sulfone (28.2%). A maximum of 91.2% conversion of benzoin has been achieved within 6 h, and the selectivities of reaction products are: methylbenzoate (37.0%) > benzil (30.5%) > benzaldehyde-dimethylacetal (22.5%) > benzoic acid (8.1%). The PS-bound complex, 1 exhibits very comparable catalytic potential. These polymer-anchored heterogeneous catalysts do not leach during catalytic action, are recyclable and show higher catalytic activity and turnover frequency than the corresponding non polymer-bound complexes. EPR and (51)V NMR spectroscopy was used to characterise methanolic solutions of 3 and 4 and to identify species formed upon addition of H(2)O(2) and/or acid and/or methyl phenyl sulfide.

Synthesis and evaluation of aminoborates derived from boric acid and diols for protecting wood against fungal and thermal degradation

Treesearch

George C. Chen

2008-01-01

N-methyl amino catechol borate (1), N-methyl amino-4-methyl catechol borate (2), N-methyl amino-4-t-butyl catechol borate (3), and N-methyl amino-2, 3-naphthyl borate (4) were synthesized by reflux of boric acid with a diol in solvent N,N-dimethyl formamide. The aminoborates were characterized by proton nuclear magnetic resonance spectroscopy, FTIR spectroscopy and...

Effects of choline 2:6-xylyl ether bromide upon the suprarenal medulla of the rat

PubMed Central

Coupland, R. E.; Exley, K. A.

1957-01-01

The administration of choline 2:6-xylyl ether bromide (TM 10) daily to rats for two weeks depletes the suprarenals of about one-half their normal content of adrenaline and noradrenaline. This depletion has been demonstrated histologically and by colorimetric and biological estimation of the amines present in extracts of the glands. Treatment with TM 10 causes similar histological signs of depletion in autografts of adrenal chromaffin tissue in the rat iris. Restoration of catechol amines in rat suprarenals, previously depleted by TM 10, occurs slowly and appears to be complete 14 days after withdrawing the drug. These results, considered in conjunction with the estimated rate of turnover of catechol amines in the rat suprarenal, lend support to the view that TM 10 may interfere with the biosynthesis of these amines. ImagesFIG. 1FIG. 2FIG. 3FIG. 4 PMID:13460235

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasan, Koroush; Brady, Patrick; Krumhansl, James L.

Fresh water scarcity is going to be a global great challenge in the near future because of the increasing population. Our water resources are limited and, hence, water treatment and recycling methods are the only alternatives for fresh water procurement in the upcoming decades. Water treatment and recycling methods serve to remove harmful or problematic constituents from ground, surface and waste waters prior to its consumption, industrial supply, or other uses. Scale formation in industrial and domestic installations is still an important problem during water treatment. In water treatment, silica scaling is a real and constant concern for plant operations.more » The focus of this study is on the viability of using a combination of catechol and active carbon to remove dissolved silica from concentrated cooling tower water (CCTW). Various analytical methods, such as ICP-MS and UV-vis, were used to understand the structure-property relationship between the material and the silica removal results. UV-Vis indicates that catechol can react with silica ions and form a silica-catecholate complex. The speciation calculation of catechol and silica shows that catechol and silica bind in the pH range of 8 – 10; there is no evidence of linkage between them in neutral and acidic pHs. The silica removal results indicate that using ~4g/L of catechol and 10g/L active carbon removes up to 50% of the dissolved silica from the CCTW.« less

Amperometric detection of catechol using tyrosinase modified electrodes enhanced by the layer-by-layer assembly of gold nanocubes and polyelectrolytes.

PubMed

Karim, Md Nurul; Lee, Ji Eun; Lee, Hye Jin

2014-11-15

A novel amperometric biosensor for catechol was developed using the layer-by-layer (LbL) self-assembly of positively charged hexadecyltrimethylammonium stabilized gold nanocubes (AuNCs), negatively charged poly(sodium 4-styrenesulfonate) and tyrosinase on a screen printed carbon electrode (SPCE). A carboxylic acid terminated alkanethiol assembled on electrochemically deposited Au nanoparticles on a SPCE was used as a platform for LbL assembly. Each SPCE sensor surface was terminated with tyrosinase and the electrocatalytic response due to the tyrosinase reaction with catechol was measured using cyclic voltammetry and square wave voltammetry (SWV). The effect of introducing AuNCs into the LbL assembly to further enhance the catechol detection performance was then investigated by comparing the SWV results to those from biosensors created using both the tyrosinase modified LbL assembly in the absence of NCs and the covalent attachment of tyrosinase. A wide dynamic range from 10nM to 80 µM of catechol with an excellent sensitivity of 13.72 A/M and a detection limit of 0.4 nM were both achieved alongside a good selectivity and reproducibility for the AuNC-modified electrodes. As a demonstration, the optimized biosensor design was applied to determine catechol concentrations in tea samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Free radical scavenging potency of quercetin catecholic colonic metabolites: Thermodynamics of 2H+/2e- processes.

PubMed

Amić, Ana; Lučić, Bono; Stepanić, Višnja; Marković, Zoran; Marković, Svetlana; Dimitrić Marković, Jasmina M; Amić, Dragan

2017-03-01

Reaction energetics of the double (2H + /2e - ), i.e., the first 1H + /1e - (catechol→ phenoxyl radical) and the second 1H + /1e - (phenoxyl radical→ quinone) free radical scavenging mechanisms of quercetin and its six colonic catecholic metabolites (caffeic acid, hydrocaffeic acid, homoprotocatechuic acid, protocatechuic acid, 4-methylcatechol, and catechol) were computationally studied using density functional theory, with the aim to estimate the antiradical potency of these molecules. We found that second hydrogen atom transfer (HAT) and second sequential proton loss electron transfer (SPLET) mechanisms are less energy demanding than the first ones indicating 2H + /2e - processes as inherent to catechol moiety. The Gibbs free energy change for reactions of inactivation of selected free radicals indicate that catecholic colonic metabolites constitute an efficient group of more potent scavengers than quercetin itself, able to deactivate various free radicals, under different biological conditions. They could be responsible for the health benefits associated with regular intake of flavonoid-rich diet. Copyright © 2016 Elsevier Ltd. All rights reserved.

Organic impurity profiling of 3,4-methylenedioxymethamphetamine (MDMA) synthesised from catechol.

PubMed

Heather, Erin; Shimmon, Ronald; McDonagh, Andrew M

2015-03-01

This work examines the organic impurity profile of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from catechol (1,2-dihydroxybenzene), a common chemical reagent available in industrial quantities. The synthesis of MDMA from catechol proceeded via the common MDMA precursor safrole. Methylenation of catechol yielded 1,3-benzodioxole, which was brominated and then reacted with magnesium allyl bromide to form safrole. Eight organic impurities were identified in the synthetic safrole. Safrole was then converted to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using two synthetic methods: Wacker oxidation (Route 1) and an isomerisation/peracid oxidation/acid dehydration method (Route 2). MDMA was then synthesised by reductive amination of MDP2P. Thirteen organic impurities were identified in MDMA synthesised via Route 1 and eleven organic impurities were identified in MDMA synthesised via Route 2. Overall, organic impurities in MDMA prepared from catechol indicated that synthetic safrole was used in the synthesis. The impurities also indicated which of the two synthetic routes was utilised. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Degradation and COD removal of catechol in wastewater using the catalytic ozonation process combined with the cyclic rotating-bed biological reactor.

PubMed

Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

2015-07-01

The effect of ozonation catalyzed with MgO/granular activated carbon (MgO/GAC) composite as a pretreatment process on the performance of cyclic rotating-bed biological reactor (CRBR) for the catechol removal from wastewater has been investigated. CRBR with acclimated biomasses could efficiently remove catechol and its related COD from wastewater at organic loading rate (OLR) of 7.82 kg COD/m(3).d (HRT of 9 h). Then, OLR increased to 15.64 kg COD/m(3).d (HRT of 4.5 h) and CRBR failed. Catalytic ozonation process (COP) used as a pre-treatment and could improve the performance of the failed CRBR. The overall removal efficiency of the combined process attained respective steady states of 91% and 79% for degradation and COD removal of catechol. Therefore, the combined process is more effective in degradation and COD removal of catechol; it is also a viable alternative for upgrading industrial wastewater treatment plant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inactivation of urease by catechol: Kinetics and structure.

PubMed

Mazzei, Luca; Cianci, Michele; Musiani, Francesco; Lente, Gábor; Palombo, Marta; Ciurli, Stefano

2017-01-01

Urease is a Ni(II)-containing enzyme that catalyzes the hydrolysis of urea to yield ammonia and carbamate at a rate 10 15 times higher than the uncatalyzed reaction. Urease is a virulence factor of several human pathogens, in addition to decreasing the efficiency of soil organic nitrogen fertilization. Therefore, efficient urease inhibitors are actively sought. In this study, we describe a molecular characterization of the interaction between urease from Sporosarcina pasteurii (SPU) and Canavalia ensiformis (jack bean, JBU) with catechol, a model polyphenol. In particular, catechol irreversibly inactivates both SPU and JBU with a complex radical-based autocatalytic multistep mechanism. The crystal structure of the SPU-catechol complex, determined at 1.50Å resolution, reveals the structural details of the enzyme inhibition. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and Characterization of Macrocyclic Polyether N,N'-Diallyl-7,16-diaza-1,4,10,13-tetraoxa-dibenzo-18-crown-6.

PubMed

Toeri, Julius; Laborie, Marie-Pierre

2016-01-29

In this study an efficient and direct production procedure for a macrocyclic polyether N,N'-diallyl-7,16-diaza-1,4,10,13-tetraoxa-dibenzo-18-crown-6 from the reaction of catechol and N,N-bis(2-chloroethyl)prop-2-en-1-amine in n-butanol in the presence of a strong base is reported. The synthesis involves a two-step addition of sodium hydroxide to enhance the cyclization process, and at the end of the reaction, the reaction mixture is neutralized and the solvent replaced with water in-situ through distillation to afford a relatively pure precipitate that is easily recrystallized from acetone. The yield of the macrocycle was 36%-45% and could be scaled-up to one-mole quantities. The structure and purity of this compound was verified on the basis of elemental analysis, IR, UV-Vis, ¹H-, (13)C-NMR, 2D-NMR, mass spectroscopy, and thermal analysis. The white crystalline compound has a sharp melting point of 124 °C and a crystallization temperature of 81.4 °C determined by differential scanning calorimetry. Our motivation behind the synthesis of the bibracchial lariat azacrown polyether ligand was to examine its possible applications in ion-selective polymer-supported materials.

Photogeneration of H2O2 in Water-Swollen SPEEK/PVA Polymer Films.

PubMed

Lockhart, PaviElle; Little, Brian K; Slaten, B L; Mills, G

2016-06-09

Efficient reduction of O2 took place via illumination with 350 nm photons of cross-linked films containing a blend of sulfonated poly(ether etherketone) and poly(vinyl alcohol) in contact with air-saturated aqueous solutions. Swelling of the solid macromolecular matrices in H2O enabled O2 diffusion into the films and also continuous extraction of the photogenerated H2O2, which was the basis for a method that allowed quantification of the product. Peroxide formed with similar efficiencies in films containing sulfonated polyketones prepared from different precursors and the initial photochemical process was found to be the rate-determining step. Generation of H2O2 was most proficient in the range of 4.9 ≤ pH ≤ 8 with a quantum yield of 0.2, which was 10 times higher than the efficiencies determined for solutions of the polymer blend. Increases in temperature as well as [O2] in solution were factors that enhanced the H2O2 generation. H2O2 quantum yields as high as 0.6 were achieved in H2O/CH3CN mixtures with low water concentrations, but peroxide no longer formed when film swelling was suppressed. A mechanism involving reduction of O2 by photogenerated α-hydroxy radicals from the polyketone in competition with second-order radical decay processes explains the kinetic features. Higher yields result from the films because cross-links present in them hinder diffusion of the radicals, limiting their decay and enhancing the oxygen reduction pathway.

Facile and scalable fabrication of polymer-ceramic composite electrolyte with high ceramic loadings

NASA Astrophysics Data System (ADS)

Pandian, Amaresh Samuthira; Chen, X. Chelsea; Chen, Jihua; Lokitz, Bradley S.; Ruther, Rose E.; Yang, Guang; Lou, Kun; Nanda, Jagjit; Delnick, Frank M.; Dudney, Nancy J.

2018-06-01

Solid state electrolytes are a promising alternative to flammable liquid electrolytes for high-energy lithium battery applications. In this work polymer-ceramic composite electrolyte membrane with high ceramic loading (greater than 60 vol%) is fabricated using a model polymer electrolyte poly(ethylene oxide) + lithium trifluoromethane sulfonate and a lithium-conducting ceramic powder. The effects of processing methods, choice of plasticizer and varying composition on ionic conductivity of the composite electrolyte are thoroughly investigated. The physical, structural and thermal properties of the composites are exhaustively characterized. We demonstrate that aqueous spray coating followed by hot pressing is a scalable and inexpensive technique to obtain composite membranes that are amazingly dense and uniform. The ionic conductivity of composites fabricated using this protocol is at least one order of magnitude higher than those made by dry milling and solution casting. The introduction of tetraethylene glycol dimethyl ether further increases the ionic conductivity. The composite electrolyte's interfacial compatibility with metallic lithium and good cyclability is verified by constructing lithium symmetrical cells. A remarkable Li+ transference number of 0.79 is discovered for the composite electrolyte.

Water-Enabled Healing of Conducting Polymer Films.

PubMed

Zhang, Shiming; Cicoira, Fabio

2017-10-01

The conducting polymer polyethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) has become one of the most successful organic conductive materials due to its high air stability, high electrical conductivity, and biocompatibility. In recent years, a great deal of attention has been paid to its fundamental physicochemical properties, but its healability has not been explored in depth. This communication reports the first observation of mechanical and electrical healability of PEDOT:PSS thin films. Upon reaching a certain thickness (about 1 µm), PEDOT:PSS thin films damaged with a sharp blade can be electrically healed by simply wetting the damaged area with water. The process is rapid, with a response time on the order of 150 ms. Significantly, after being wetted the films are transformed into autonomic self-healing materials without the need of external stimulation. This work reveals a new property of PEDOT:PSS and enables its immediate use in flexible and biocompatible electronics, such as electronic skin and bioimplanted electronics, placing conducting polymers on the front line for healing applications in electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell attachment functionality of bioactive conducting polymers for neural interfaces.

PubMed

Green, Rylie A; Lovell, Nigel H; Poole-Warren, Laura A

2009-08-01

Bioactive coatings for neural electrodes that are tailored for cell interactions have the potential to produce superior implants with improved charge transfer capabilities. In this study synthetically produced anionically modified laminin peptides DEDEDYFQRYLI and DCDPGYIGSR were used to dope poly(3,4-ethylenedioxythiophene) (PEDOT) electrodeposited on platinum (Pt) electrodes. Performance of peptide doped films was compared to conventional polymer PEDOT/paratoluene sulfonate (pTS) films using SEM, XPS, cyclic voltammetry, impedance spectroscopy, mechanical hardness and adherence. Bioactivity of incorporated peptides and their affect on cell growth was assessed using a PC12 neurite outgrowth assay. It was demonstrated that large peptide dopants produced softer PEDOT films with a minimal decrease in electrochemical stability, compared to the conventional dopant, pTS. Cell studies revealed that the YFQRYLI ligand retained neurite outgrowth bioactivity when DEDEDYFQRYLI was used as a dopant, but the effect was strongly dependant on initial cell attachment. Alternate peptide dopant, DCDPGYIGSR was found to impart superior cell attachment properties when compared to DEDEDYFQRYLI, but attachment on both peptide doped polymers could be enhanced by coating with whole native laminin.

Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

NASA Astrophysics Data System (ADS)

Lin, Chun-Chiao; Huang, Chih-Kuo; Hung, Yu-Chieh; Chang, Mei-Ying

2016-08-01

An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

Sulfonated macro-RAFT agents for the surfactant-free synthesis of cerium oxide-based hybrid latexes.

PubMed

Garnier, Jérôme; Warnant, Jérôme; Lacroix-Desmazes, Patrick; Dufils, Pierre-Emmanuel; Vinas, Jérôme; van Herk, Alex

2013-10-01

Three types of amphiphatic macro-RAFT agents were employed as compatibilizers to promote the polymerization reaction at the surface of nanoceria for the synthesis of CeO2-based hybrid latexes. Macro-RAFT copolymers and terpolymers were first synthesized employing various combinations of butyl acrylate as a hydrophobic monomer and acrylic acid (AA) and/or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as hydrophilic monomers. After characterizing the adsorption of these macro-RAFT agents at the cerium oxide surface by UV-visible spectrometry, emulsion copolymerization reactions of styrene and methyl acrylate were then carried out in the presence of the surface-modified nanoceria. Dynamic Light Scattering and cryo-Transmission Electron Microscopy were employed to confirm the hybrid structure of the final CeO2/polymer latexes, and proved that the presence of acrylic acid units in amphiphatic macro-RAFT agents enabled an efficient formation of hybrid structures, while the presence of AMPS units, when combined with AA units, resulted in a better distribution of cerium oxide nanoclusters between latex particles. Copyright © 2013 Elsevier Inc. All rights reserved.

A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

PubMed

Yang, Bin; Lv, Yin; Zhu, Jing-Yi; Han, Yun-Tao; Jia, Hui-Zhen; Chen, Wei-Hai; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

2014-08-01

The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis and evaluation of borates derived from boric acid and diols for the protection of wood against fungal decay and thermal degradation

Treesearch

George C. Chen

2004-01-01

N,N-dimethyl amino carbinol catechol borate(1). N,N-dimethyl amino carbinol-4-methyl catechol borate(2), N,N-dimethyl amino carbinol-4-t- butyl catechol borate(3). N,N-dimethyl amino carbinol-2,3-naphthyl borate 4) were synthesized by refluxing boric acid and diol in DMF(N,N-dimethyl formamide). The borates were characterized by NMR. Wood impregnated with borate 1,2 or...

Mechanistic aspects of the tyrosinase oxidation of hydroquinone.

PubMed

Ramsden, Christopher A; Riley, Patrick A

2014-06-01

Contradictory reports on the behaviour of hydroquinone as a tyrosinase substrate are reconciled in terms of the ability of the initially formed ortho-quinone to tautomerise to the thermodynamically more stable para-quinone isomer. Oxidation of phenols by native tyrosinase requires activation by in situ formation of a catechol formed via an enzyme generated ortho-quinone. In the special case of hydroquinone, catechol formation is precluded by rapid tautomerisation of the ortho-quinone precursor to catechol formation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation

NASA Astrophysics Data System (ADS)

Deng, Chao; Zhang, Qiu Gen; Han, Guang Lu; Gong, Yi; Zhu, Ai Mei; Liu, Qing Lin

2013-10-01

Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles.Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles. Electronic supplementary information (ESI) available: Synthesis and characterization of SPEK-C; effect of the sulfonation degree on membrane formation; structure and properties of the self-assembled membranes; separation of cyt.c by the self-assembled membranes; size-selective separation of gold nanoparticles by the self-assembled membranes; comparison with commercial flat sheet ultrafiltration membranes. See DOI: 10.1039/c3nr03362g

Enhancing the efficiency of thiomers: Utilizing a highly mucoadhesive polymer as backbone for thiolation and preactivation.

PubMed

Prüfert, Felix; Bonengel, Sonja; Menzel, Claudia; Bernkop-Schnürch, Andreas

2017-01-01

The objective of this study was to develop a novel thiomer with enhanced mucoadhesive properties using a highly mucoadhesive polymeric backbone. Fixomer™ A-30 (poly(methacrylic acid-co-sodium acrylamidomethyl propane sulfonate)), exhibiting a mucoadhesive strength superior to that of all other polymers, was thiolated by conjugation with l-cysteine and furthermore preactivated with 2-mercaptonicotinic acid (MNA). The resulting derivatives Fix-SH and Fix-S-MNA exhibited coupling rates of 755μmol thiol groups and 304μmol MNA per gram polymer, respectively. The mucoadhesive profile was evaluated with three different methods: tensile studies, rotating cylinder and rheological synergism. In tensile studies, a total work of adhesion of above 500μJ was determined for the unmodified polymer that increased to around 750μJ after thiolation and around 1500μJ after preactivation. The adhesion time of Fix-SH on the rotating cylinder was 3.7-fold and that of Fix-S-MNA 6.8-fold longer compared to the unmodified polymer. A rheological synergism was observed for the unmodified polymer as well as the derivatives with a non-significant difference for Fix-SH but a 5.44-fold improvement for Fix-S-MNA. Fix-S-MNA showed a significantly improved swelling behavior with a water-uptake up to the 30-fold of its initial weight over >50h whereas thiolation showed only slight improvements. Derivatization had no significant influence on cell viability. According to the results, Fix-S-MNA seems to be a suitable polymer for mucoadhesive drug delivery systems. Copyright © 2016. Published by Elsevier B.V.

Improving Fire Resistance of Cotton Fabric through Layer-by-Layer Assembled Graphene Multilayer Nanocoating

NASA Astrophysics Data System (ADS)

Jang, Wonjun; Chung, Il Jun; Kim, Junwoo; Seo, Seongmin; Park, Yong Tae; Choi, Kyungwho

2018-05-01

In this study, thin films containing poly(vinyl alcohol) (PVA) and graphene nanoplatelets (GNPs), stabilized with poly(4-styrene-sulfonic acid) (PSS), were assembled by a simple and cost-effective layer-by-layer (LbL) technique in order to introduce the anti-flammability to cotton. These antiflammable layers were characterized by using UV-vis spectrometry and quartz crystal microbalance as a function of the number of bilayers deposited. Scanning electron microscopy was used to visualize the morphology of the thin film coatings on the cotton fabric. The graphene-polymer thin films introduced anti-flammable properties through thermally stable carbonaceous layers at a high temperature. The thermal stability and flame retardant property of graphene-coated cotton was demonstrated by thermogravimetric analysis, cone calorimetry, and vertical flame test. The results indicate that LbL-assembled graphene-polymer thin films can be applied largely in the field of flame retardant.

Single nanopore transport of synthetic and biological polyelectrolytes in three-dimensional hybrid microfluidic/nanofluidic devices

DOE PAGES

King, Travis L.; Gatimu, Enid N.; Bohn, Paul W.

2009-01-02

This paper presents a study of electrokinetic transport in single nanopores integrated into vertically-stacked three-dimensional hybrid microfluidic/nanofluidic structures. In these devices single nanopores, created by focused ion beam (FIB) milling in thin polymer films, provide fluidic connection between two vertically separated, perpendicular microfluidic channels. Experiments address both systems in which the nanoporous membrane is composed of the same (homojunction) or different (heterojunction) polymer as the microfluidic channels. These devices are then used to study the electrokinetic transport properties of synthetic (i.e., polystyrene sulfonate and polyallylamine) and biological (i.e.,DNA) polyelectrolytes across these nanopores. Single nanopore transport of polyelectrolytes across these nanoporesmore » using both electrical current measurements and confocal microscopy. Both optical and electrical measurements indicate that electroosmotic transport is predominant over electrophoresis in single nanopores with d > 180 nm, consistent with results obtained under similar conditions for nanocapillary array membranes.« less

Electrostimulated Release of Neutral Drugs from Polythiophene Nanoparticles: Smart Regulation of Drug-Polymer Interactions.

PubMed

Puiggalí-Jou, Anna; Micheletti, Paolo; Estrany, Francesc; Del Valle, Luis J; Alemán, Carlos

2017-09-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles are loaded with curcumin and piperine by in situ emulsion polymerization using dodecyl benzene sulfonic acid both as a stabilizer and a doping agent. The loaded drugs affect the morphology, size, and colloidal stability of the nanoparticles. Furthermore, kinetics studies of nonstimulated drug release have evidenced that polymer···drug interactions are stronger for curcumin than for piperine. This observation suggests that drug delivery systems based on combination of the former drug with PEDOT are much appropriated to show an externally tailored release profile. This is demonstrated by comparing the release profiles obtained in presence and absence of electrical stimulus. Results indicate that controlled and time-programmed release of curcumin is achieved in a physiological medium by applying a negative voltage of -1.25 V to loaded PEDOT nanoparticles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water-compatible 'aspartame'-imprinted polymer grafted on silica surface for selective recognition in aqueous solution.

PubMed

Singh, Meenakshi; Kumar, Abhishek; Tarannum, Nazia

2013-05-01

Molecularly imprinted polymers selective for aspartame have been prepared using N-[2-ammonium-ethyl-piperazinium) maleimidopropane sulfonate copolymer bearing zwitterionic centres along the backbone via a surface-confined grafting procedure. Aspartame, a dipeptide, is commonly used as an artificial sweetener. Polymerisation on the surface was propagated by means of Michael addition reaction on amino-grafted silica surface. Electrostatic interactions along with complementary H-bonding and other hydrophobic interactions inducing additional synergetic effect between the template (aspartame) and the imprinted surface led to the formation of imprinted sites. The MIP was able to selectively and specifically take up aspartame from aqueous solution and certain pharmaceutical samples quantitatively. Hence, a facile, specific and selective technique using surface-grafted specific molecular contours developed for specific and selective uptake of aspartame in the presence of various interferrants, in different kinds of matrices is presented.

Polymer modified glassy carbon electrode for the electrochemical determination of caffeine in coffee.

PubMed

Amare, Meareg; Admassie, Shimelis

2012-05-15

4-Amino-3-hydroxynaphthalene sulfonic acid (AHNSA) was electropolymerized on a glassy carbon electrode. The deposited film showed electrocatalytic activity towards the oxidation of caffeine. The polymer-modified electrode showed high sensitivity, selectivity and stability in the determination of caffeine in coffee. The peak current increased linearly with the concentration of caffeine in the range of 6 × 10(-8) to 4 × 10(-5) mol L(-1), with a detection limit of 1.37 × 10(-7) mol L(-1) (LoD = 3δ/slope). Analysis of caffeine in coffee was affected neither by sample matrices nor by structurally similar compounds. Recoveries ranging between 93.75 ± 2.32 and 100.75 ± 3.32 were achieved from coffee extracts indicating the applicability of the developed method for real sample analyses. Copyright © 2012 Elsevier B.V. All rights reserved.

Accelerated Thermal Depolymerization of Cyclic Polyphthalaldehyde with a Polymeric Thermoacid Generator.

PubMed

Lopez Hernandez, Hector; Lee, Olivia P; Possanza, Catherine; Kaitz, Joshua A; Park, Chan Woo; Plantz, Christopher L; Moore, Jeffrey S; White, Scott R

2018-04-30

Thermally triggerable polymer films that degrade at modest temperatures (≈85 °C) are created from a blend of cyclic polyphthalaldehyde (cPPA) and a polymeric thermoacid generator, poly(vinyl tert-butyl carbonate sulfone) (PVtBCS). PVtBCS depolymerizes when heated, generating acid which initiates the depolymerization of cPPA into volatile byproducts. The mass loss onset for 2 wt% PVtBCS/cPPA is 22 °C lower than the onset for neat cPPA alone in dynamic thermogravimetric analysis experiments. Increased concentrations of PVtBCS increase the rate of depolymerization of cPPA. Raman spectroscopy reveals that the monomer, o-phthalaldehyde, is the main depolymerization product of the acid-catalyzed depolymerization of cPPA. The PVtBCS/cPPA blend is a promising material for the design and manufacture of transient electronic packaging and polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lignolytic-consortium omics analyses reveal novel genomes and pathways involved in lignin modification and valorization.

PubMed

Moraes, Eduardo C; Alvarez, Thabata M; Persinoti, Gabriela F; Tomazetto, Geizecler; Brenelli, Livia B; Paixão, Douglas A A; Ematsu, Gabriela C; Aricetti, Juliana A; Caldana, Camila; Dixon, Neil; Bugg, Timothy D H; Squina, Fabio M

2018-01-01

Lignin is a heterogeneous polymer representing a renewable source of aromatic and phenolic bio-derived products for the chemical industry. However, the inherent structural complexity and recalcitrance of lignin makes its conversion into valuable chemicals a challenge. Natural microbial communities produce biocatalysts derived from a large number of microorganisms, including those considered unculturable, which operate synergistically to perform a variety of bioconversion processes. Thus, metagenomic approaches are a powerful tool to reveal novel optimized metabolic pathways for lignin conversion and valorization. The lignin-degrading consortium (LigMet) was obtained from a sugarcane plantation soil sample. The LigMet taxonomical analyses (based on 16S rRNA) indicated prevalence of Proteobacteria , Actinobacteria and Firmicutes members, including the Alcaligenaceae and Micrococcaceae families, which were enriched in the LigMet compared to sugarcane soil. Analysis of global DNA sequencing revealed around 240,000 gene models, and 65 draft bacterial genomes were predicted. Along with depicting several peroxidases, dye-decolorizing peroxidases, laccases, carbohydrate esterases, and lignocellulosic auxiliary (redox) activities, the major pathways related to aromatic degradation were identified, including benzoate (or methylbenzoate) degradation to catechol (or methylcatechol), catechol ortho-cleavage, catechol meta-cleavage, and phthalate degradation. A novel Paenarthrobacter strain harboring eight gene clusters related to aromatic degradation was isolated from LigMet and was able to grow on lignin as major carbon source. Furthermore, a recombinant pathway for vanillin production was designed based on novel gene sequences coding for a feruloyl-CoA synthetase and an enoyl-CoA hydratase/aldolase retrieved from the metagenomic data set. The enrichment protocol described in the present study was successful for a microbial consortium establishment towards the lignin and aromatic metabolism, providing pathways and enzyme sets for synthetic biology engineering approaches. This work represents a pioneering study on lignin conversion and valorization strategies based on metagenomics, revealing several novel lignin conversion enzymes, aromatic-degrading bacterial genomes, and a novel bacterial strain of potential biotechnological interest. The validation of a biosynthetic route for vanillin synthesis confirmed the applicability of the targeted metagenome discovery approach for lignin valorization strategies.

Understanding Marine Biocorrosion: Experiments with Artificial and Natural Seawater

DTIC Science & Technology

2015-11-04

study of microbiologically infl uenced marine corrosion (MIMC) and the consideration of nutrients for microorganisms. Recent MIMC investigations have...conclusion of the experiment the concentration of sulphide was below the detection limit (Figure 13.3 ). Generally, KW seawater had higher numbers of...sulphides. Supporting their hypothesis, diagnostic catechols, which are known aerobic degradation products of hydrocarbons, were detected in the NRL

Aerobic Biodegradation of Trichloroethylene.

DTIC Science & Technology

1987-07-01

into C02 and unidentified nonvolatile products. Phenol, 41 toiin- andq- cresol were found to replace the site water requirement for TCE metabolism...identified as phenol. Other aromatic compounds that could support TCE degradation were toluene, o- cresol , and m- cresol . The degradation could be...Production...... .. .. .. . 17 4. Test for the Catechol Ortho °Ring-Fission Pathway . 18 5. Oxidation of Aromatic Compounds ............. .18 6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Storey, Robson, F.; Mauritz, Kenneth, A.; Patton, Derek, L.

The overall objective of this project was the development and evaluation of novel hydrocarbon fuel cell (FC) membranes that possess high temperature performance and long term chemical/mechanical durability in proton exchange membrane (PEM) fuel cells (FC). The major research theme was synthesis of aromatic hydrocarbon polymers of the poly(arylene ether sulfone) (PAES) type containing sulfonic acid groups tethered to the backbone via perfluorinated alkylene linkages and in some cases also directly attached to the phenylene groups along the backbone. Other research themes were the use of nitrogen-based heterocyclics instead of acid groups for proton conduction, which provides high temperature, lowmore » relative humidity membranes with high mechanical/thermal/chemical stability and pendant moieties that exhibit high proton conductivities in the absence of water, and synthesis of block copolymers consisting of a proton conducting block coupled to poly(perfluorinated propylene oxide) (PFPO) blocks. Accomplishments of the project were as follows: 1) establishment of a vertically integrated program of synthesis, characterization, and evaluation of FC membranes, 2) establishment of benchmark membrane performance data based on Nafion for comparison to experimental membrane performance, 3) development of a new perfluoroalkyl sulfonate monomer, N,N-diisopropylethylammonium 2,2-bis(p-hydroxyphenyl) pentafluoropropanesulfonate (HPPS), 4) synthesis of random and block copolymer membranes from HPPS, 5) synthesis of block copolymer membranes containing high-acid-concentration hydrophilic blocks consisting of HPPS and 3,3'-disulfonate-4,4'-dichlorodiphenylsulfone (sDCDPS), 6) development of synthetic routes to aromatic polymer backbones containing pendent 1H-1,2,3-triazole moieties, 7) development of coupling strategies to create phase-separated block copolymers between hydrophilic sulfonated prepolymers and commodity polymers such as PFPO, 8) establishment of basic performance properties of experimental membranes, 9) fabrication and FC performance testing of membrane electrode assemblies (MEA) from experimental membranes, and 10) measurement of ex situ and in situ membrane durability of experimental membranes. Although none of the experimental hydrocarbon membranes that issued from the project displayed proton conductivities that met DOE requirements, the project contributed to our basic understanding of membrane structure-property relationships in a number of key respects. An important finding of the benchmark studies is that physical degradation associated with humidity and temperature variations in the FC tend to open new fuel crossover pathways and act synergistically with chemical degradation to accelerate overall membrane degradation. Thus, for long term membrane survival and efficient fuel utilization, membranes must withstand internal stresses due to humidity and temperature changes. In this respect, rigid aromatic hydrocarbon fuel cell membranes, e.g. PAES, offer an advantage over un-modified Nafion membranes. The benchmark studies also showed that broadband dielectric spectroscopy is a potentially powerful tool in assessing shifts in the fundamental macromolecular dynamics caused by Nafion chemical degradation, and thus, this technique is of relevance in interrogating proton exchange membrane durability in fuel cells and macromolecular dynamics as coupled to proton migration, which is of fundamental relevance in proton exchange membranes in fuel cells. A key finding from the hydrocarbon membrane synthesis effort was that rigid aromatic polymers containing isolated ion exchange groups tethered tightly to the backbone (short tether), such as HPPS, provide excellent mechanical and durability properties but do not provide sufficient conductivity, in either random or block configuration, when used as the sole ion exchange monomer. However, we continue to hypothesize that longer tethers, and tethered groups spaced more closely within the hydrophilic chain elements of the polymer, will yield highly conductive materials with excellent mechanical properties. Another key finding is the superior performance of PAES membranes upon being subjected to open circuit voltage (OCV) testing. Throughout the course of the experiment, OCV for the PAES not only stayed higher but also decayed at a much lower rate, which is attributed to better dimensional stability and improved mechanical and gas barrier properties. The rigid backbone reinforcement of PAES adds gas diffusion tortuosity that restricts membrane degradation and OCV loss due to reduced fuel crossover. The overall results of creep, contractile stress and mechanical tensile tests confirm the conclusion that degraded MEAs of PAES membrane can handle stress and are more likely to be more durable in a fuel cell, even after subjected to 62h of OCV degradation.« less

Modification of the effects of guanethidine on cardiac catechol amines by various agents

PubMed Central

Bhagat, B.

1964-01-01

A study has been made of the effect of injections of guanethidine in rats, in depleting catechol amines from the whole cardiac ventricles and from various subcellular fractions. Unlike reserpine, guanethidine first affected the concentration of the amines in the soluble fraction of the cell. Neither [2-(2,6-dimethylphenoxy)-propyl]trimethylammonium chloride monohydrate (β-methyl xylocholine) nor hemicholinium affected the endogenous catechol amines or the uptake of injected noradrenaline, but each significantly reduced the action of guanethidine in depleting catechol amines. Administration of choline chloride after hemicholinium reversed its influence on guanethidine depletion. In cats, cocaine potentiated the pressor response to noradrenaline, but antagonized the response to tyramine and guanethidine, while bretylium and N-o-chlorobenzyl-N'N”-dimethylguanidine sulphate (BW392C60) potentiated the responses to noradrenaline, tyramine and guanethidine. PMID:14190459

Nanostructured membranes based on polysulfone homopolymers and copolymers

NASA Astrophysics Data System (ADS)

Nunes, Suzana

Polyethersulfone is one of the most successful polymers for membranes with applications varying from seawater desalination to hemodialysis. Their manufacture however is traditionally done by solution casting and phase inversion using solvents, which are now considered negative for the environment. We have been working on the membrane manufacture using ionic liquids as green solvent alternative. Polyethersulfone, and polyetherimide sulfone membranes, as flat-sheet and hollow fibers, were prepared from solutions in different ionic liquids. Thermodynamic and rheological investigation were conducted to optimize the membrane morphology, leading to permeances of 20-65 Lm-2h-1bar-1 useful for instance for separations of peptides with molecular weight in the range of 800 to 3500 gmol-1. We also synthesized block copolymers with polysulfone segments and explored them for membrane preparation with low fouling, high porosity and narrow pore size distribution. The self-assembly of the copolymer in solution, leading to the membrane formation was investigated by cryo electron microscopy, supported by modeling (dissipative particle dynamics). In collaboration with: Dooli Kim, Yihui xie, Burhannudin Sutisna, King Abdullah University of Science and Technology

Nonlinear optical probe of biopolymer adsorption on colloidal particle surface: poly-L-lysine on polystyrene sulfate microspheres.

PubMed

Eckenrode, Heather M; Dai, Hai-Lung

2004-10-12

A nonlinear optical technique--second harmonic generation (SHG)--has been applied to characterize the adsorption of poly-L-lysine on micrometer size polystyrene particles, whose surface is covered with negatively charged sulfonate groups, in aqueous solutions. Adsorption behavior of the biopolymer with two chain lengths (14 and 75 amino acid units; PL14 and PL75) has been examined. Centrifugation experiments were also performed to support the adsorption measurements made using SHG. The adsorption free energies of the two polymers PL75 and PL14 are determined as -16.57 and -14.40 kcal/mol, respectively. The small difference in the adsorption free energies of the two chain lengths, however, leads to dramatic difference in the concentration needed for saturated surface coverage: nearly 50 times higher concentration is needed for the smaller polymer. Under acidic colloidal conditions, polylysine is found to adsorb in a relatively flat conformation on the surface. The surface area that each polylysine molecule occupies is nearly 1 order of magnitude larger than the size of the molecule in its extended form. The low adsorption density is likely a result from Coulombic repulsion between the positive charges on the amino acid units of PL. The measurements demonstrate the utility of SHG as an efficient and sensitive experimental approach for measuring adsorption characteristics of bio/macromolecules on colloidal particles and define surface and colloidal conditions for achieving maximum surface coverage of a widely used biopolymer. Copyright 2004 American Chemical Society

Ionic Liquids in Selective Oxidation: Catalysts and Solvents.

PubMed

Dai, Chengna; Zhang, Jie; Huang, Chongpin; Lei, Zhigang

2017-05-24

Selective oxidation has an important role in environmental and green chemistry (e.g., oxidative desulfurization of fuels and oxidative removal of mercury) as well as chemicals and intermediates chemistry to obtain high-value-added special products (e.g., organic sulfoxides and sulfones, aldehydes, ketones, carboxylic acids, epoxides, esters, and lactones). Due to their unique physical properties such as the nonvolatility, thermal stability, nonexplosion, high polarity, and temperature-dependent miscibility with water, ionic liquids (ILs) have attracted considerable attention as reaction solvents and media for selective oxidations and are considered as green alternatives to volatile organic solvents. Moreover, for easy separation and recyclable utilization, IL catalysts have attracted unprecedented attention as "biphasic catalyst" or "immobilized catalyst" by immobilizing metal- or nonmetal-containing ILs onto mineral or polymer supports to combine the unique properties of ILs (chemical and thermal stability, capacity for extraction of polar substrates and reaction products) with the extended surface of the supports. This review highlights the most recent outcomes on ILs in several important typical oxidation reactions. The contents are arranged in the series of oxidation of sulfides, oxidation of alcohols, epoxidation of alkenes, Baeyer-Villiger oxidation reaction, oxidation of alkanes, and oxidation of other compounds step by step involving ILs as solvents, catalysts, reagents, or their combinations.

Synthesis and characterization of aminated perfluoro polymer electrolytes

NASA Astrophysics Data System (ADS)

Page-Belknap, Zachary Stephan Glenn

Polymer electrolytes have been developed for use in anion exchange membrane fuel cells for years. However, due to the highly corrosive environment within these fuel cells, poor chemical stability of the polymers and low ion conductivity have led to high development costs and thus prevention from widespread commercialization. The work in this study aims to provide a solution to these problems through the synthesis and characterization of a novel polymer electrolyte. The 800 EW 3M PFSA sulfonyl fluoride precursor was aminated with 3-(dimethylamino)-1-propylamine to yield a functional polymer electrolyte following quaternization, referred to in this work as PFSa-PTMa. 1 M solutions of LiPF6, HCL, KOH, NaOH, CsOH, NaHCO3 and Na2CO3 were used to exchange the polymer to alternate counterion forms. Chemical structure analysis was performed using both FT and ATR infrared spectroscopy to confirm sulfonyl fluoride replacement and the absence of sulfonic acid sites. Mechanical testing of the polymer, following counterion exchange with KOH, at saturated conditions and 60 ºC exhibited a tensile strength of 13 +/- 2.0 MPa, a Young's modulus of 87 +/- 16 MPa and a degree of elongation reaching 75% +/- 9.1%, which indicated no mechanical degradation following exposure to a highly basic environment. Conductivities of the polymer in the Cl- and OH- counterion forms at saturated conditions and 90 ºC were observed at 26 +/- 8.0 mS cm-1 and 1.1 +/- 0.1 mS cm-1, respectively. OH- conductivities were slightly above those observed for CO32- and HCO 3- counterions at the same conditions, 0.63 +/- 0.18 and 0.66 +/- 0.21 mS cm-1 respectively. The ion exchange capacity (IEC) of the polymer in the Cl- counterion form was measured via titration at 0.57 meq g-1 which correlated to 11.2 +/- 0.10 water molecules per ion site when at 60ºC and 95% relative humidity. The IEC of the polymer in the OH- counterion form following titration expressed nearly negligible charge density, less than 0.01 meq g -1. The low OH- conductivities and IEC were attributed to the formation of a predominately zwitterionic polymer when exposed to a strong base. Removal of the sulfonamide proton following counterion exchange with a strong base and formation of a zwitterion was confirmed by FTIR with the absence of a primary amine stretch between 3000-3600 cm-1. 1H NMR analysis of small molecule analogues established that the sulfonamide site was not methylated during quaternization as evident by the exclusion of a strong singlet around 2.9 ppm. pH indication tests with Thymolphthalein illuminated the slight presence of free OH- ions within the polymer following counterion exchange thus validating the low IEC and formation of a predominately zwitterionic polymer. Recommended future work with this polymer electrolyte consists of fine tuning the polymer to be less or completely zwitterionic, pKa analysis of the sulfonamide linkage with small molecule analogues, implementation into microbial fuel cell and biological separation processes for pH regulation, and development as a support infrastructure for ionic liquids.

An implantable smart magnetic nanofiber device for endoscopic hyperthermia treatment and tumor-triggered controlled drug release.

PubMed

Sasikala, Arathyram Ramachandra Kurup; Unnithan, Afeesh Rajan; Yun, Yeo-Heung; Park, Chan Hee; Kim, Cheol Sang

2016-02-01

The study describes the design and synthesis of an implantable smart magnetic nanofiber device for endoscopic hyperthermia treatment and tumor-triggered controlled drug release. This device is achieved using a two-component smart nanofiber matrix from monodisperse iron oxide nanoparticles (IONPs) as well as bortezomib (BTZ), a chemotherapeutic drug. The IONP-incorporated nanofiber matrix was developed by electrospinning a biocompatible and bioresorbable polymer, poly (d,l-lactide-co-glycolide) (PLGA), and tumor-triggered anticancer drug delivery is realized by exploiting mussel-inspired surface functionalization using 2-(3,4-dihydroxyphenyl)ethylamine (dopamine) to conjugate the borate-containing BTZ anticancer drug through a catechol metal binding in a pH-sensitive manner. Thus, an implantable smart magnetic nanofiber device can be exploited to both apply hyperthermia with an alternating magnetic field (AMF) and to achieve cancer cell-specific drug release to enable synergistic cancer therapy. These results confirm that the BTZ-loaded mussel-inspired magnetic nanofiber matrix (BTZ-MMNF) is highly beneficial not only due to the higher therapeutic efficacy and low toxicity towards normal cells but also, as a result of the availability of magnetic nanoparticles for repeated hyperthermia application and tumor-triggered controlled drug release. The current work report on the design and development of a smart nanoplatform responsive to a magnetic field to administer both hyperthermia and pH-dependent anticancer drug release for the synergistic anticancer treatment. The iron oxide nanoparticles (IONPs) incorporated nanofiber matrix was developed by electrospinning a biocompatible polymer, poly (d,l-lactide-co-glycolide) (PLGA), and tumor-triggered anticancer drug delivery is realized by surface functionalization using 2-(3,4-dihydroxyphenyl)ethylamine (dopamine) to conjugate the boratecontaining anticancer drug bortezomib through a catechol metal binding in a pH-sensitive manner. This implantable magnetic nanofiber device can be exploited to apply hyperthermia with an alternating magnetic field and to achieve cancer cell-specific drug release to enable synergistic cancer therapy, which results in an improvement in both quality of life and patient compliance. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Preparation of activated carbon monolith by application of phenolic resins as carbon precursors

NASA Astrophysics Data System (ADS)

Sajad, Mehran; Kazemzad, Mahmood; Hosseinnia, Azarmidokht

2014-04-01

In the current work, activated carbon monoliths have been prepared by application of different phenolic hydrocarbons namely catechol and resorcinol as carbon precursors. For synthesis of carbon monolith, the precursors have been mixed with Genapol PF-10 as template and then polymerized in the presence of lysine as catalyst. Then the polymerized monolith carbonized in inert atmosphere at 700°C and activated by water steam at 550°C. It was found that resorcinol polymerization is easier than catechol and occurred at 90°C while for polymerization of catechol elevated temperature of 120°C at hydrothermal condition is necessary. The prepared activated carbon samples have been characterized by various analysis methods including scanning electron microscopy (SEM), surface area measurement, and transmission electron microscopy (TEM). The adsorptions of three different aromatic hydrocarbons by the prepared activated carbon samples have also been investigated by high performance liquid chromatography (HPLC) and UV-Vis spectroscopy. It was found that carbon monolith prepared by catechol as carbon precursor has higher adsorpability and strength in comparison with the other sample. The higher performance of carbon monolith prepared by catechol can be associated with its higher active sites in comparison with resorcinol.

Enhanced waterflooding design with dilute surfactant concentrations for North Sea conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michels, A.M.; Djojosoeparto, R.S.; Haas, H.

1996-08-01

Efficient selection procedures for surfactants have been applied to design a low-concentration surfactant-flooding process for North Sea oilfield application. Anionic surfactants of the propoxy ethoxy glyceryl sulfonate type can be used at 0.1 wt% concentrations together with sacrificial agents and without a polymer drive. Currently estimated unit technical costs (UTC`s)--at 8%--for application in the North Sea oil fields range frommore » $81 to $$94/incremental m{sup 3}, without taking uncertainty factors into account. Including such factors would likely add another $$31/m{sup 3} to the costs.« less

High Performance of Supercapacitor from PEDOT:PSS Electrode and Redox Iodide Ion Electrolyte

PubMed Central

Gao, Xing; Zu, Lei; Cai, Xiaomin; Li, Ce; Lian, Huiqin; Liu, Yang; Wang, Xiaodong; Cui, Xiuguo

2018-01-01

Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity of 51.3 mAh/g and the retention of specific capacity of 87.6% after 3000 cycles due to the synergic effect through a simultaneous redox reaction both in electrode and electrolyte, as well as the catalytic activity for reduction of triiodide of the PEDOT:PSS. PMID:29772662

Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization. 10. Influence of Molecular Weight on the Phase Transitions of Poly(Omega-((4-Cyano-4’-Biphenyl)oxy)alkyl Vinyl Ethers)s with Nonyl and Decanyl Alkyl Groups

DTIC Science & Technology

1990-10-16

washed with concentrated sulfuric acid , then with water, dried over anhydrous magnesium sulfate, refluxed over calcium hydride and freshly distilled...oxide, filtered, and fractionally distilled under reduced pressure. Trifluoromethane sulfonic acid (triflic acid , 98%, Aldrich) w s distilled under...flask. Then the flask was filled with argon, cooled to 0°C and the methylene chloride, dimethyl sulfide and triflic acid were added via a syringe. The

Modification of epoxy-reinforced glass-cloth composites with a perfluorinated alkyl ether elastomer

NASA Technical Reports Server (NTRS)

Rosser, R. W.; Chen, T. S.; Taylor, M.

1984-01-01

A perfluorinated alkyl ether diacyl fluoride prepolymer (molecular weight about 1500) was coreacted with Epon 828 epoxy resin and diamino diphenyl sulfone to obtain an elastomer-toughened, glass-cloth composite. Improvements in flexural toughness, impact resistance, and water resistance, without loss of strength, modulus of elasticity or a lowering of the glass-transition temperature, were realized over those of the unmodified composite. Factors concerning optimization of the process are discussed. Results suggest that a simultaneously interpenetrating polymer network may be formed which gives rise to a measured improvement in composite mechanical properties.

Covalent conjugation of graphene oxide with methotrexate and its antitumor activity

NASA Astrophysics Data System (ADS)

Wojtoniszak, M.; Urbas, K.; Perużyńska, M.; Kurzawski, M.; Droździk, M.; Mijowska, E.

2013-05-01

Here, we have functionalized graphene oxide with anticancer drug methotrexate through amide bonding. A kinetics of the drug release from graphene oxide in physiological solution - phosphate buffered saline (PBS) containing different biocompatible polymers have been investigated. Dispersion of MTX-GO in poly sodium-4-styrene sulfonate and poly ethylene glycol resulted in increase of the release time. The material was characterized with transmission electron microscopy, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy. Furthermore, antineoplastic action against human breast adenocarcinoma cell line MCF7 of MTX-GO and empty graphene oxide was explored.

Immobilization of Trametes hirsuta laccase into poly(3,4-ethylenedioxythiophene) and polyaniline polymer-matrices

NASA Astrophysics Data System (ADS)

Wang, Xiaoju; Sjöberg-Eerola, Pia; Immonen, Kirsi; Bobacka, Johan; Bergelin, Mikael

The immobilization of Trametes hirsuta laccase (ThL) in the poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) matrices was carried out in order to study the catalytic effect of ThL in different biocathode structures in a biofuel cell application. By using 2,2‧-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) as a mediator compound, the immobilized ThL in both polymer matrices, exhibited catalytic activity for the reduction of oxygen into water. The amount of ThL was adjustable in the PEDOT matrix by controlling the working parameters, such as the charge density used in the electropolymerization of EDOT monomer and the ThL concentration used in the electropolymerization electrolyte. In the PEDOT biocathode structure, the utilization of porous material as the PEDOT supporting template was studied in order to improve the current density generated per unit area/volume. Reticulated vitreous carbon foam (RVC foam) was chosen as the PEDOT supporting template material and the biocathodes were manufactured by in situ entrapment of ThL into PEDOT films polymerized on the RVC foam. These biocathodes possessed a high cathodic open circuit potential and produced a large current density, reaching 1 mA cm -3 at 0.45 V when 19.5 μg ml -1 of ThL was used in the electrolyte. The performance of these biocathodes was extremely sensitive to variations in pH and the optimal working pH was around 4.2. The biocathode reserved 80%, 50%, and 30% of the catalytic activity after storage in a +4 °C buffer solution for 1 day, 1 week, and 1 month, respectively. The PANI matrix was prepared in a form of printable ink where ThL was in situ entrapped in the PANI matrix during the laccase activated polymerization of aniline using a chemical batch reactor method. Different amounts of the ThL-containing printable PANI ink were then applied on carbon paper and the performance of the ink was subsequently electrochemically characterized. In this way, not only two different polymer matrices, but also two different matrix manufacturing procedures could be compared.

Homology modeling, simulation and molecular docking studies of catechol-2, 3-Dioxygenase from Burkholderia cepacia: Involved in degradation of Petroleum hydrocarbons.

PubMed

Ajao, At; Kannan, M; Yakubu, Se; Vj, Umoh; Jb, Ameh

2012-01-01

Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3- dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene, Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255, Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Å. In addition to that, the above mentioned substrate except pyrene all other made π-π stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Å. All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of catalyzing the above-mentioned substrate.

Homology modeling, simulation and molecular docking studies of catechol-2, 3-Dioxygenase from Burkholderia cepacia: Involved in degradation of Petroleum hydrocarbons

PubMed Central

Ajao, AT; Kannan, M; Yakubu, SE; VJ, Umoh; JB, Ameh

2012-01-01

Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3- dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene, Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255, Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Å. In addition to that, the above mentioned substrate except pyrene all other made π-π stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Å. All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of catalyzing the above-mentioned substrate. PMID:23144539

Tunneling in green tea: understanding the antioxidant activity of catechol-containing compounds. A variational transition-state theory study.

PubMed

Tejero, Ismael; Gonzalez-García, Núria; Gonzalez-Lafont, Angels; Lluch, José M

2007-05-09

The catechol functionality present in the catechins is responsible for the protective effects exerted by green tea against a wide range of human diseases. High-level electronic structure calculations and canonical variational transition-state theory including multidimensional tunneling corrections have allowed us to understand the key factors of the antioxidant effectiveness of the catechol group. This catechol group forms two hydrogen bonds with the two oxygen atoms of the lipid peroxyl radical, leading to a very compact reactant complex. This fact produces an extremely narrow adiabatic potential-energy profile corresponding to the hydrogen abstraction by the peroxyl radical, which makes it possible for a huge tunneling contribution to take place. So, quantum-mechanical tunneling highly increases the corresponding rate constant value, in such a way that catechins become able to trap the lipid peroxyl radicals in a dominant competition with the very damaging free-radical chain-lipid peroxidation reaction.

Catabolism of benzoate and monohydroxylated benzoates by Amycolatopsis and Streptomyces spp.

PubMed Central

Grund, E; Knorr, C; Eichenlaub, R

1990-01-01

Eight actinomycetes of the genera Amycolatopsis and Streptomyces were tested for the degradation of aromatic compounds by growth in a liquid medium containing benzoate, monohydroxylated benzoates, or quinate as the principal carbon source. Benzoate was converted to catechol. The key intermediate in the degradation of salicylate was either catechol or gentisate, while m-hydroxybenzoate was metabolized via gentisate or protocatechuate. p-Hydroxybenzoate and quinate were converted to protocatechuate. Catechol, gentisate, and protocatechuate were cleaved by catechol 1,2-dioxygenase, gentisate 1,2-dioxygenase, and protocatechuate 3,4-dioxygenase, respectively. The requirement for glutathione in the gentisate pathway was dependent on the substrate and the particular strain. The conversion of p-hydroxybenzoate to protocatechuate by p-hydroxybenzoate hydroxylase was gratuitously induced by all substrates that were metabolized via protocatechuate as an intermediate, while protocatechuate 3,4-dioxygenase was gratuitously induced by benzoate and salicylate in two Amycolatopsis strains. PMID:2339895

Polymers in cell encapsulation from an enveloped cell perspective.

PubMed

de Vos, Paul; Lazarjani, Hamideh Aghajani; Poncelet, Denis; Faas, Marijke M

2014-04-01

In the past two decades, many polymers have been proposed for producing immunoprotective capsules. Examples include the natural polymers alginate, agarose, chitosan, cellulose, collagen, and xanthan and synthetic polymers poly(ethylene glycol), polyvinyl alcohol, polyurethane, poly(ether-sulfone), polypropylene, sodium polystyrene sulfate, and polyacrylate poly(acrylonitrile-sodium methallylsulfonate). The biocompatibility of these polymers is discussed in terms of tissue responses in both the host and matrix to accommodate the functional survival of the cells. Cells should grow and function in the polymer network as adequately as in their natural environment. This is critical when therapeutic cells from scarce cadaveric donors are considered, such as pancreatic islets. Additionally, the cell mass in capsules is discussed from the perspective of emerging new insights into the release of so-called danger-associated molecular pattern molecules by clumps of necrotic therapeutic cells. We conclude that despite two decades of intensive research, drawing conclusions about which polymer is most adequate for clinical application is still difficult. This is because of the lack of documentation on critical information, such as the composition of the polymer, the presence or absence of confounding factors that induce immune responses, toxicity to enveloped cells, and the permeability of the polymer network. Only alginate has been studied extensively and currently qualifies for application. This review also discusses critical issues that are not directly related to polymers and are not discussed in the other reviews in this issue, such as the functional performance of encapsulated cells in vivo. Physiological endocrine responses may indeed not be expected because of the many barriers that the metabolites encounter when traveling from the blood stream to the enveloped cells and back to circulation. However, despite these diffusion barriers, many studies have shown optimal regulation, allowing us to conclude that encapsulated grafts do not always follow nature's course but are still a possible solution for many endocrine disorders for which the minute-to-minute regulation of metabolites is mandatory. Copyright © 2013 Elsevier B.V. All rights reserved.

Water Sorption in Electron-Beam Evaporated SiO2 on QCM Crystals and Its Influence on Polymer Thin Film Hydration Measurements.

PubMed

Kushner, Douglas I; Hickner, Michael A

2017-05-30

Spectroscopic ellipsometry (SE) and quartz crystal microbalance (QCM) measurements are two critical characterization techniques routinely employed for hydration studies of polymer thin films. Water uptake by thin polymer films is an important area of study to investigate antifouling surfaces, to probe the swelling of thin water-containing ionomer films, and to conduct fundamental studies of polymer brush hydration and swelling. SiO 2 -coated QCM crystals, employed as substrates in many of these hydration studies, show porosity in the thin electron-beam (e-beam) evaporated SiO 2 layer. The water sorption into this porous SiO 2 layer requires correction of the optical and mass characterization of the hydrated polymer due to changes in the SiO 2 layer as it sorbs water. This correction is especially important when experiments on SiO 2 -coated QCM crystals are compared to measurements on Si wafers with dense native SiO 2 layers. Water adsorption filling void space during hydration in ∼200-260 nm thick SiO 2 layers deposited on a QCM crystal resulted in increased refractive index of the layer during water uptake experiments. The increased refractive index led to artificially higher polymer swelling in the optical modeling of the hydration experiments. The SiO 2 -coated QCM crystals showed between 6 and 8% void as measured by QCM and SE, accounting for 60%-85% of the measured polymer swelling in the low humidity regime (<20% RH) and 25%-40% of the polymer swelling in the high humidity regime (>70% RH) from optical modeling for 105 and 47 nm thick sulfonated polymer films. Correcting the refractive index of the SiO 2 layer for its water content resulted in polymer swelling that successfully resembled swelling measured on a silicon wafer with nonporous native oxide.

Hot-hole extraction from quantum dot to molecular adsorbate.

PubMed

Singhal, Pallavi; Ghosh, Hirendra N

2015-03-09

Ultrafast thermalized and hot-hole-transfer processes have been investigated in CdSe quantum dot (QD)/catechol composite systems in which hole transfer from photoexcited QDs to the catechols is thermodynamically favorable. A series of catechol derivatives were selected with different electron-donating and -withdrawing groups, and the effect of these groups on hole transfer and charge recombination (CR) dynamics has been investigated. The hole-transfer time was determined using the fluorescence upconversion technique and found to be 2-10 ps depending on the molecular structure of the catechol derivatives. The hot-hole-transfer process was followed after monitoring 2S luminescence of CdSe QDs. Interestingly, hot-hole extraction was observed only in the CdSe/3-methoxycatechol (3-OCH3) composite system owing to the higher electron-donating property of the 3-methoxy group. To confirm the extraction of the hot hole and to monitor the CR reaction in CdSe QD/catechol composite systems, ultrafast transient absorption studies have been carried out. Ultrafast transient-absorption studies show that the bleach recovery kinetics of CdSe QD at the 2S excitonic position is much faster in the presence of 3-OCH3. This faster bleach recovery at the 2S position in CdSe/3-OCH3 suggests hot-hole transfer from CdSe QD to 3-OCH3. CR dynamics in CdSe QD/catechol composite systems was followed by monitoring the excitonic bleach at the 1S position and was found to decrease with free energy of the CR reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interactions among catechol-O-methyltransferase genotype, parenting, and sex predict children’s internalizing symptoms and inhibitory control: Evidence for differential susceptibility

PubMed Central

SULIK, MICHAEL J.; EISENBERG, NANCY; SPINRAD, TRACY L.; LEMERY-CHALFANT, KATHRYN; SWANN, GREGORY; SILVA, KASSONDRA M.; REISER, MARK; STOVER, DARYN A.; VERRELLI, BRIAN C.

2015-01-01

We used sex, observed parenting quality at 18 months, and three variants of the catechol-O-methyltransferase gene (Val158Met [rs4680], intron1 [rs737865], and 3′-untranslated region [rs165599]) to predict mothers’ reports of inhibitory and attentional control (assessed at 42, 54, 72, and 84 months) and internalizing symptoms (assessed at 24, 30, 42, 48, and 54 months) in a sample of 146 children (79 male). Although the pattern for all three variants was very similar, Val158Met explained more variance in both outcomes than did intron1, the 3′-untranslated region, or a haplotype that combined all three catechol-O-methyltransferase variants. In separate models, there were significant three-way interactions among each of the variants, parenting, and sex, predicting the intercepts of inhibitory control and internalizing symptoms. Results suggested that Val158Met indexes plasticity, although this effect was moderated by sex. Parenting was positively associated with inhibitory control for methionine–methionine boys and for valine–valine/valine–methionine girls, and was negatively associated with internalizing symptoms for methionine–methionine boys. Using the “regions of significance” technique, genetic differences in inhibitory control were found for children exposed to high-quality parenting, whereas genetic differences in internalizing were found for children exposed to low-quality parenting. These findings provide evidence in support of testing for differential susceptibility across multiple outcomes. PMID:25159270

Oxidation of Benzene to Phenol, Catechol, and 1,2,3-Trihydroxybenzene by Toluene 4-Monooxygenase of Pseudomonas mendocina KR1 and Toluene 3-Monooxygenase of Ralstonia pickettii PKO1

PubMed Central

Tao, Ying; Fishman, Ayelet; Bentley, William E.; Wood, Thomas K.

2004-01-01

Aromatic hydroxylations are important bacterial metabolic processes but are difficult to perform using traditional chemical synthesis, so to use a biological catalyst to convert the priority pollutant benzene into industrially relevant intermediates, benzene oxidation was investigated. It was discovered that toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1, toluene 3-monooxygenase (T3MO) of Ralstonia pickettii PKO1, and toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 convert benzene to phenol, catechol, and 1,2,3-trihydroxybenzene by successive hydroxylations. At a concentration of 165 μM and under the control of a constitutive lac promoter, Escherichia coli TG1/pBS(Kan)T4MO expressing T4MO formed phenol from benzene at 19 ± 1.6 nmol/min/mg of protein, catechol from phenol at 13.6 ± 0.3 nmol/min/mg of protein, and 1,2,3-trihydroxybenzene from catechol at 2.5 ± 0.5nmol/min/mg of protein. The catechol and 1,2,3-trihydroxybenzene products were identified by both high-pressure liquid chromatography and mass spectrometry. When analogous plasmid constructs were used, E. coli TG1/pBS(Kan)T3MO expressing T3MO formed phenol, catechol, and 1,2,3-trihydroxybenzene at rates of 3 ± 1, 3.1 ± 0.3, and 0.26 ± 0.09 nmol/min/mg of protein, respectively, and E. coli TG1/pBS(Kan)TOM expressing TOM formed 1,2,3-trihydroxybenzene at a rate of 1.7 ± 0.3 nmol/min/mg of protein (phenol and catechol formation rates were 0.89 ± 0.07 and 1.5 ± 0.3 nmol/min/mg of protein, respectively). Hence, the rates of synthesis of catechol by both T3MO and T4MO and the 1,2,3-trihydroxybenzene formation rate by TOM were found to be comparable to the rates of oxidation of the natural substrate toluene for these enzymes (10.0 ± 0.8, 4.0 ± 0.6, and 2.4 ± 0.3 nmol/min/mg of protein for T4MO, T3MO, and TOM, respectively, at a toluene concentration of 165 μM). PMID:15240250

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

PubMed

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

2015-12-04

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

PubMed Central

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T.C. Mike

2015-01-01

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications. PMID:26690232

Integration of a Graphite/PMMA CompositeElectrode into a Poly(methyl methacrylate) (PMMA) Substrate for Electrochemical Detection in Microchips

PubMed Central

Regel, Anne; Lunte, Susan

2013-01-01

Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by microchip electrophoresis (ME). PMID:23670816

Electrical stimulation promotes nerve cell differentiation on polypyrrole/poly (2-methoxy-5 aniline sulfonic acid) composites.

PubMed

Liu, Xiao; Gilmore, Kerry J; Moulton, Simon E; Wallace, Gordon G

2009-12-01

The purpose of this work was to investigate for the first time the potential biomedical applications of novel polypyrrole (PPy) composites incorporating a large polyelectrolyte dopant, poly (2-methoxy-5 aniline sulfonic acid) (PMAS). The physical and electrochemical properties were characterized. The PPy/PMAS composites were found to be smooth and hydrophilic and have low electrical impedance. We demonstrate that PPy/PMAS supports nerve cell (PC12) differentiation, and that clinically relevant 250 Hz biphasic current pulses delivered via PPy/PMAS films significantly promote nerve cell differentiation in the presence of nerve growth factor (NGF). The capacity of PPy/PMAS composites to support and enhance nerve cell differentiation via electrical stimulation renders them valuable for medical implants for neurological applications.

Align and random electrospun mat of PEDOT:PSS and PEDOT:PSS/RGO

NASA Astrophysics Data System (ADS)

Sarabi, Ghazale Asghari; Latifi, Masoud; Bagherzadeh, Roohollah

2018-01-01

In this research work we fabricated two ultrafine conductive nanofibrous layers to investigate the materilas composition and their properties for the preparation of supercapacitor materials application. In first layer, a polymer and a conductive polymer were used and second layer was a composition of polymer, conductive polymer and carbon-base material. In both cases align and randomized mat of conductive nanofibers were fabricated using electrospinning set up. Conductive poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT:PSS) nanofibers were electrospun by dissolving fiber-forming polymer and polyvinyl alcohol (PVA) in an aqueous dispersion of PEDOT:PSS. The effect of addition of reduced graphene oxide (RGO) was considered for nanocomposite layer. The ultrafine conductive polymer fibers and conductive nanocomposite fibrous materials were also fabricated using an electrospinning process. A fixed collector and a rotating drum were used for random and align nanofibers production, respectively. The resulted fibers were characterized and analyzed by SEM, FTIR and two-point probe conductivity test. The average diameter of nanofibers measured by ImageJ software indicated that the average fiber diameter for first layer was 100 nm and for nanocomposite layer was about 85 nm. The presence of PEDOT:PSS and RGO in the nanofibers was confirmed by FT-IR spectroscopy. The conductivity of align and random layers was characterized. The conductivity of PEDOT:PSS nanofibers showed higher enhancement by addition of RGO in aqueous dispersion. The obtained results showed that alignment of fibrous materials can be considered as an engineering tool for tuning the conductivity of fibrous materials for many different applications such as supercapacitors, conductive and transparent materials.

Origins of the helical wrapping of phenyleneethynylene polymers about single-walled carbon nanotubes.

PubMed

Von Bargen, Christopher D; MacDermaid, Christopher M; Lee, One-Sun; Deria, Pravas; Therien, Michael J; Saven, Jeffery G

2013-10-24

The highly charged, conjugated polymer poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) has been shown to wrap single-wall carbon nanotubes (SWNTs), adopting a robust helical superstructure. Surprisingly, PPES adopts a helical rather than a linear conformation when adhered to SWNTs. The complexes formed by PPES and related polymers upon helical wrapping of a SWNT are investigated using atomistic molecular dynamics (MD) simulations in the presence and absence of aqueous solvent. In simulations of the PPES/SWNT system in an aqueous environment, PPES spontaneously takes on a helical conformation. A potential of mean force, ΔA(ξ), is calculated as a function of ξ, the component of the end-to-end vector of the polymer chain projected on the SWNT axis; ξ is a monotonic function of the polymer's helical pitch. ΔA(ξ) provides a means to quantify the relative free energies of helical conformations of the polymer when wrapped about the SWNT. The aqueous system possesses a global minimum in ΔA(ξ) at the experimentally observed value of the helical pitch. The presence of this minimum is associated with preferred side chain conformations, where the side chains adopt conformations that provide van der Waals contact between the tubes and the aliphatic components of the side chains, while exposing the anionic sulfonates for aqueous solvation. The simulations provide a free energy estimate of a 0.2 kcal/mol/monomer preference for the helical over the linear conformation of the PPES/SWNT system in an aqueous environment.

Photo-assisted generation of phospholipid polymer substrates for regiospecific protein conjugation and control of cell adhesion.

PubMed

Tanaka, Masako; Iwasaki, Yasuhiko

2016-08-01

Novel photo-reactive phospholipid polymers were synthesized for use in the preparation of nonfouling surfaces with protein conjugation capacity. Poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-ran-N-methacryloyl-(l)-tyrosinemethylester (MAT)] (P(MPC/MAT)) was synthesized by conventional radical polymerization, with the MAT units capable of being oxidized by 254nm UV irradiation. Because of this photo-oxidation, active species such as catechol and quinone were alternately generated in the copolymer. A silicon wafer was subjected to surface modification through spin coating of P(MPC/MAT) from an aqueous solution for use as a model substrate. The surface was then irradiated several times with UV light. The thickness of the polymer layers formed on the Si wafers was influenced by various parameters such as polymer concentration, UV irradiation time, and composition of the MAT units in P(MPC/MAT). Oxidized MAT units were advantageous not only for polymer adhesion to a solid surface but also for protein conjugation with the adhered polymers. The amount of protein immobilized on UV-irradiated P(MPC/MAT) was dependent on the composition of the MAT units in the polymer. Furthermore, it was confirmed that protein immobilization on the polymer occurred through the oxidized MAT units because the protein adsorption was significantly reduced upon blocking these units through pretreatment with glycine. Conjugation of regiospecific protein could also be achieved through the use of a photomask. In addition, nonspecific protein adsorption was reduced on the non-irradiated regions whose surface was covered with physisorbed P(MPC/MAT). Therefore, P(MPC/MAT) can be used in the preparation of nonfouling substrates, which enable micrometer-sized manipulation of proteins through photo-irradiation. Function of proteins immobilized on MPC copolymers was also confirmed by cell adhesion test. As such, photo-reactive MPC copolymers are suitable for performing controlled protein conjugation and preparing polymer-protein hybrid platforms for use in biomedical and diagnostic devices. Novel photo-reactive phospholipid polymers have been synthesized for immobilization on solid surfaces and regiospecific protein conjugation. Tyrosine residues embedded in 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymers could be photo-oxidized, resulting in polymers able to form layers on a solid surface and conjugate with proteins. Moreover, nonspecific biofouling on the surface significantly reduced when the oxidized tyrosine units in the polymer layers were blocked. Upon UV irradiation through a photomask, the UV-exposed tyrosine units were selectively oxidized, forming the only specific regions in which protein conjugation could occur. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis, molecular structure and magnetic properties of a rhenium(IV) compound with catechol

NASA Astrophysics Data System (ADS)

Cuevas, A.; Geis, L.; Pintos, V.; Chiozzone, R.; Sanchíz, J.; Hummert, M.; Schumann, H.; Kremer, C.

2009-03-01

A novel Re(IV) complex containing catechol as ligand has been prepared and characterized. The crystal structure of (HNEt 3)(NBu 4)[ReCl 4(cat)]·H 2cat was determined. The rhenium ion presents a distorted octahedral geometry, being bonded to a bidentate catecholate group and four chloride anions. The magnetic properties of the complex were studied, a /2 D/ (the energy gap between ±3/2 and ±1/2 Kramers doublets) value of 190(10) cm -1. This is the largest /2 D/ value reported for Re(IV) up to now.

Proton-Coupled Electron Transfer and Substituent Effects in Catechol-Based Deep Eutectic Solvents: Gross and Fine Tuning of Redox Activity.

PubMed

Smith, Parker J; Goeltz, John C

2017-12-07

The 1,2-diol moiety in a variety of substituted catechols allows formation of room temperature ionic melts in a 2:1 ratio with choline chloride or choline dihydrogen citrate. These deep eutectic solvents were 4.3-6.6 M in redox active catechols. Substituents on 3- and 4-substituted catechols shift both E° and pK a such that Hammett parameters predict the observed E p for oxidation in square wave voltammetry. The proton acceptor for the proton-coupled oxidation shifts the observed E p more strongly than the substituents within the substituents and acceptors reported here. The shift is predicted well by the pK a of the conjugate acid of the proton acceptor, i.e., water in aqueous solutions or chloride or dihydrogen citrate in the DESs in this study. Together, the substituent and the proton acceptor allow gross and fine-tuning of the oxidation potential for catechol over 750 mV, the first demonstration of control of the thermodynamics of proton-coupled electron transfer in deep eutectic solvents. Changing the substituents on the HBD affords fine control in tens of millivolts, while changing the base strength of the anion of the organic salt affords gross control across hundreds of millivolts.

Biochar, activated carbon, and carbon nanotubes have different effects on fate of (14)C-catechol and microbial community in soil.

PubMed

Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

2015-10-30

This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of (14)C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of (14)C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of (14)C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of (14)C-catechol and microbial community in soil.

Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

PubMed Central

Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

2015-01-01

This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil. PMID:26515132

Dielectric Properties of Polyether Sulfone/Bismaleimide Resin Composite Based on Nanolumina Modified by Super-Critical Ethanol

NASA Astrophysics Data System (ADS)

Chen, Yufei; Li, Zhichao; Teng, Chengjun; Li, Fangliang; Han, Yang

2016-11-01

Nano-alumina was chemically modified with super-critical ethanol enabling a surface active coating. Modified nano-alumina was incorporated in polymer blends based on thermoplastic polyether sulfone and thermosetting bismaleimide resin to produce novel nanocomposites designated as SCE-Al2O3/PES-MBAE. In the SCE-Al2O3/PES-MBAE nano-composites, the matrix was originally formed from 4,4'-diamino diphenyl methane bismaleimide (MBMI) using the diluents of 3,3'-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE), while polyether sulfone (PES) was used as toughening agent along with super-critically modified nano-alumina (SCE-Al2O3) as filler material. The content of SCE-Al2O3 was varied from 0 wt.% to 6 wt.%. The nano-composites were characterized for their morphological, spectroscopic and dielectric properties. Fourier transform infrared spectroscopy (FT-IR) indicated that ethanol molecules had adhered to the surface of the nano-Al2O3 in super-critical state. A reaction between MBMI and allyl compound occurred and SCE-Al2O3 was doped into the polymer matrix. Volume resistivity of the composite initially increased and then decreased. The modification due to SCE-Al2O3 could overcome the undesirable impact of PES by using a bare minimum level of SCE-Al2O3. The dielectric constant ( ɛ) and dielectric loss (tan δ) as in the case of volume resistivity were initially increased and then decreased with the content of SCE-Al2O3 in the composite. The dielectric constant, dielectric loss and dielectric strength of SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE nano-composite were 3.53 (100 Hz), 1.52 × 10-3 (100 Hz) and 15.66 kV/mm, respectively, which indicated that the dielectric properties of the composite fulfilled the basic requirements of electrical and insulating material. It was evident from the morphological analysis that the SCE-Al2O3 was evenly dispersed at the nanoscale; for example, the size of SCE-Al2O3 in SCE-Al2O3 (4 wt.%)/PES (5 wt.%)-MBAE measured less than 50 nm.

Glucose- and Cellulose-Derived Ni/C-SO3H Catalysts for Liquid Phase Phenol Hydrodeoxygenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasakov, Stanislav; Zhao, Chen; Barath, Eszter

2015-01-19

Sulfonated carbons were explored as functionalized supports for Ni nanoparticles to hydrodeoxygenate (HDO) phenol. Both hexadecane and water were used as solvents. The dual-functional Ni catalysts supported on sulfonated carbon (Ni/C-SO3H) showed high rates for phenol hydrodeoxygenation in liquid hexadecane, but not in water. Glucose and cellulose were precursors to the carbon supports. Changes in the carbons resulting from sulfonation of the carbons resulted in variations of carbon sheet structures, morphologies and the surface concentrations of acid sites. While the C-SO3H supports were active for cyclohexanol dehydration in hexadecane and water, Ni/C-SO3H only catalyzed the reduction of phenol to cyclohexanolmore » in water. The state of 3 – 5 nm grafted Ni particles was analyzed by in situ X-ray absorption spectroscopy. The results show that the metallic Ni was rapidly formed in situ without detectable leaching to the aqueous phase, suggesting that just the acid functions on Ni/C-SO3H are inhibited in presence of water. Using in situ IR spectroscopy, it was shown that even in hexadecane, phenol HDO is limited by the dehydration step. Thus, phenol HDO catalysis was further improved by physically admixing C-SO3H with the Ni/C-SO3H catalyst to balance the two catalytic functions. The minimum addition of 7 wt.% C-SO3H to the most active of the Ni/C-SO3H catalysts enabled nearly quantitative conversion of phenol and the highest selectivity (90%) towards cyclohexane in 6 h, at temperatures as low as 473 K, suggesting that the proximity to Ni limits the acid properties of the support.« less

Glucose- and cellulose-derived Ni/C-SO3H catalysts for liquid phase phenol hydrodeoxygenation.

PubMed

Kasakov, Stanislav; Zhao, Chen; Baráth, Eszter; Chase, Zizwe A; Fulton, John L; Camaioni, Donald M; Vjunov, Aleksei; Shi, Hui; Lercher, Johannes A

2015-01-19

Sulfonated carbons were explored as functionalized supports for Ni nanoparticles to hydrodeoxygenate (HDO) phenol. Both hexadecane and water were used as solvents. The dual-functional Ni catalysts supported on sulfonated carbon (Ni/C-SO3H) showed high rates for phenol hydrodeoxygenation in liquid hexadecane, but not in water. Glucose and cellulose were precursors to the carbon supports. Changes in the carbons resulting from sulfonation of the carbons resulted in variations of carbon sheet structures, morphologies and the surface concentrations of acid sites. While the C-SO3H supports were active for cyclohexanol dehydration in hexadecane and water, Ni/C-SO3H only catalysed the reduction of phenol to cyclohexanol in water. The state of 3-5 nm grafted Ni particles was analysed by in situ X-ray absorption spectroscopy. The results show that the metallic Ni was rapidly formed in situ without detectable leaching to the aqueous phase, suggesting that just the acid functions on Ni/C-SO3H are inhibited in the presence of water. Using in situ IR spectroscopy, it was shown that even in hexadecane, phenol HDO is limited by the dehydration step. Thus, phenol HDO catalysis was further improved by physically admixing C-SO3H with the Ni/C-SO3H catalyst to balance the two catalytic functions. The minimum addition of 7 wt % C-SO3H to the most active of the Ni/C-SO3H catalysts enabled nearly quantitative conversion of phenol and the highest selectivity (90%) towards cyclohexane in 6 h, at temperatures as low as 473 K, suggesting that the proximity to Ni limits the acid properties of the support. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synergistic combination of antioxidants, silver nanoparticles and chitosan in a nanoparticle based formulation: Characterization and cytotoxic effect on MCF-7 breast cancer cell lines.

PubMed

Nayak, Debasis; Minz, Aliva Prity; Ashe, Sarbani; Rauta, Pradipta Ranjan; Kumari, Manisha; Chopra, Pankaj; Nayak, Bismita

2016-05-15

Chitosan (Cs) is a biocompatible, biodegradable cationic polymer having the ability of targeted drug delivery. Vitamin E and C are not synthesized in our body thus, when encapsulated within a carrier system these vitamins in combination with/alone can be utilized for their anti-cancer potentials. The present investigation was conducted to develop a stable nanoparticle based formulation encapsulating antioxidants (Vitamin E, catechol) and silver nanoparticles synthesized from Hibiscus rosa-sinensis (HRS) petal extracts within a chitosan matrix. The prepared nanoformulations were characterized using Field emission scanning electron microscopy (Fe-SEM), X-ray diffraction (XRD) and Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR). They were further tested for their antioxidant potentials using DPPH assay, hydrogen peroxide scavenging assay, nitric oxide scavenging assay and ferrous antioxidant reducing potential assay. The nanoformulations were found to be highly hemocompatible and showed high encapsulation efficiency up to 76%. They also showed higher antioxidant activity than their base materials. Further, their anti-cancer efficacy was observed against MCF-7 breast cancer cells having IC50 values of 53.36±0.36μg/mL (chitosan-ascorbic acid-glucose), 55.28±0.85μg/mL (chitosan-Vitamin E), 63.72±0.27μg/mL (Chitosan-catechol) and 58.53±0.55μg/mL (chitosan-silver nanoparticles). Thus, the prepared formulations can be therapeutically applied for effective and targeted delivery in breast cancer treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

40 CFR 721.10711 - Alkyl substituted catechol (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10711 Alkyl substituted catechol (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

Free-Standing Conducting Polymer Films for High-Performance Energy Devices.

PubMed

Li, Zaifang; Ma, Guoqiang; Ge, Ru; Qin, Fei; Dong, Xinyun; Meng, Wei; Liu, Tiefeng; Tong, Jinhui; Jiang, Fangyuan; Zhou, Yifeng; Li, Ke; Min, Xue; Huo, Kaifu; Zhou, Yinhua

2016-01-18

Thick, uniform, easily processed, highly conductive polymer films are desirable as electrodes for solar cells as well as polymer capacitors. Here, a novel scalable strategy is developed to prepare highly conductive thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (HCT-PEDOT:PSS) films with layered structure that display a conductivity of 1400 S cm(-1) and a low sheet resistance of 0.59 ohm sq(-1). Organic solar cells with laminated HCT-PEDOT:PSS exhibit a performance comparable to the reference devices with vacuum-deposited Ag top electrodes. More importantly, the HCT-PEDOT:PSS film delivers a specific capacitance of 120 F g(-1) at a current density of 0.4 A g(-1). All-solid-state flexible symmetric supercapacitors with the HCT-PEDOT:PSS films display a high volumetric energy density of 6.80 mWh cm(-3) at a power density of 100 mW cm(-3) and 3.15 mWh cm(-3) at a very high power density of 16160 mW cm(-3) that outperforms previous reported solid-state supercapacitors based on PEDOT materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strong Photo-Amplification Effects in Flexible Organic Capacitors with Small Molecular Solid-State Electrolyte Layers Sandwiched between Photo-Sensitive Conjugated Polymer Nanolayers

PubMed Central

Lee, Hyena; Kim, Jungnam; Kim, Hwajeong; Kim, Youngkyoo

2016-01-01

We demonstrate strong photo-amplification effects in flexible organic capacitors which consist of small molecular solid-state electrolyte layers sandwiched between light-sensitive conjugated polymer nanolayers. The small molecular electrolyte layers were prepared from aqueous solutions of tris(8-hydroxyquinoline-5-sulfonic acid) aluminum (ALQSA3), while poly(3-hexylthiophene) (P3HT) was employed as the light-sensitive polymer nanolayer that is spin-coated on the indium-tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) film substrates. The resulting capacitors feature a multilayer device structure of PET/ITO/P3HT/ALQSA3/P3HT/ITO/PET, which were mechanically robust due to good adhesion between the ALQSA3 layers and the P3HT nanolayers. Results showed that the specific capacitance was increased by ca. 3-fold when a white light was illuminated to the flexible organic multilayer capacitors. In particular, the capacity of charge storage was remarkably (ca. 250-fold) enhanced by a white light illumination in the potentiostatic charge/discharge operation, and the photo-amplification functions were well maintained even after bending for 300 times at a bending angle of 180o. PMID:26846891

Strong Photo-Amplification Effects in Flexible Organic Capacitors with Small Molecular Solid-State Electrolyte Layers Sandwiched between Photo-Sensitive Conjugated Polymer Nanolayers.

PubMed

Lee, Hyena; Kim, Jungnam; Kim, Hwajeong; Kim, Youngkyoo

2016-02-05

We demonstrate strong photo-amplification effects in flexible organic capacitors which consist of small molecular solid-state electrolyte layers sandwiched between light-sensitive conjugated polymer nanolayers. The small molecular electrolyte layers were prepared from aqueous solutions of tris(8-hydroxyquinoline-5-sulfonic acid) aluminum (ALQSA3), while poly(3-hexylthiophene) (P3HT) was employed as the light-sensitive polymer nanolayer that is spin-coated on the indium-tin oxide (ITO)-coated poly(ethylene terephthalate) (PET) film substrates. The resulting capacitors feature a multilayer device structure of PET/ITO/P3HT/ALQSA3/P3HT/ITO/PET, which were mechanically robust due to good adhesion between the ALQSA3 layers and the P3HT nanolayers. Results showed that the specific capacitance was increased by ca. 3-fold when a white light was illuminated to the flexible organic multilayer capacitors. In particular, the capacity of charge storage was remarkably (ca. 250-fold) enhanced by a white light illumination in the potentiostatic charge/discharge operation, and the photo-amplification functions were well maintained even after bending for 300 times at a bending angle of 180(°).

Development of a chemiresistor sensor based on polymers-dye blend for detection of ethanol vapor.

PubMed

dos Reis, Marcos A L; Thomazi, Fabiano; Del Nero, Jordan; Roman, Lucimara S

2010-01-01

The conductive blend of the poly (3,4-ethylene dioxythiophene) and polystyrene sulfonated acid (PEDOT-PSS) polymers were doped with Methyl Red (MR) dye in the acid form and were used as the basis for a chemiresistor sensor for detection of ethanol vapor. This Au | Polymers-dye blend | Au device was manufactured by chemical vapor deposition and spin-coating, the first for deposition of the metal electrodes onto a glass substrate, and the second for preparation of the organic thin film forming ∼1.0 mm2 of active area. The results obtained are the following: (i) electrical resistance dependence with atmospheres containing ethanol vapor carried by nitrogen gas and humidity; (ii) sensitivity at 1.15 for limit detection of 26.25 ppm analyte and an operating temperature of 25 °C; and (iii) the sensing process is quickly reversible and shows very a low power consumption of 20 μW. The thin film morphology of ∼200 nm thickness was analyzed by Atomic Force Microscopy (AFM), where it was observed to have a peculiarly granulometric surface favorable to adsorption. This work indicates that PEDOT-PSS doped with MR dye to compose blend film shows good performance like resistive sensor.

Facile and scalable fabrication of polymer-ceramic composite electrolyte with high ceramic loadings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandian, Amaresh Samuthira; Chen, Xi Chelsea; Chen, Jihua

Solid state electrolytes are a promising alternative to flammable liquid electrolytes for high-energy lithium battery applications. In this work polymer-ceramic composite electrolyte membrane with high ceramic loading (greater than 60 vol%) is fabricated using a model polymer electrolyte poly(ethylene oxide) + lithium trifluoromethane sulfonate and a lithium-conducting ceramic powder. The effects of processing methods, choice of plasticizer and varying composition on ionic conductivity of the composite electrolyte are thoroughly investigated. The physical, structural and thermal properties of the composites are exhaustively characterized. We demonstrate that aqueous spray coating followed by hot pressing is a scalable and inexpensive technique to obtainmore » composite membranes that are amazingly dense and uniform. The ionic conductivity of composites fabricated using this protocol is at least one order of magnitude higher than those made by dry milling and solution casting. The introduction of tetraethylene glycol dimethyl ether further increases the ionic conductivity. The composite electrolyte's interfacial compatibility with metallic lithium and good cyclability is verified by constructing lithium symmetrical cells. As a result, a remarkable Li + transference number of 0.79 is discovered for the composite electrolyte.« less

Swelling kinetics and electrical charge transport in PEDOT:PSS thin films exposed to water vapor.

PubMed

Sarkar, Biporjoy; Jaiswal, Manu; Satapathy, Dillip K

2018-06-06

We report the swelling kinetics and evolution of the electrical charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films subjected to water vapor. Polymer films swell by the diffusion of water vapor and are found to undergo structural relaxations. Upon exposure to water vapor, primarily the hygroscopic PSS shell, which surrounds the conducting PEDOT-rich cores, takes up water vapor and subsequently swells. We found that the degree of swelling largely depends on the PEDOT to PSS ratio. Swelling driven microscopic rearrangement of the conducting PEDOT-rich cores in the PSS matrix strongly influences the electrical charge transport of the polymer film. Swelling induced increase as well as decrease of electrical resistance are observed in polymer films having different PEDOT to PSS ratio. This anomalous charge transport behavior in PEDOT:PSS films is reconciled by taking into account the contrasting swelling behavior of the PSS and the conducting PEDOT-rich cores leading to spatial segregation of PSS in films with PSS as a minority phase and by a net increase in mean separation between conducting PEDOT-rich cores for films having abundance of PSS.

High Performance Electroactive Polymer Actuators Based on Sulfonated Block Copolymers Comprising Ionic Liquids

NASA Astrophysics Data System (ADS)

Kim, Onnuri; Park, Moon Jeong

2015-03-01

Electroactive polymer (EAP) actuators that show reversible deformation under external electric stimulus have attracted great attention toward a range of biomimetic applications such as microsensors and artificial muscles. Key challenges to advance the technologies can be placed on the achievement of fast response time, low driving voltage, and durable operation in air. In present study, we are motivated to solve these issues by employing self-assembled block copolymers containing ionic liquids (ILs) as polymer layers in the actuator based on knowledge of factors affecting electromechanical properties of actuators. By controlling the block architecture and molecular weight of block copolymers, bending strain and durability were controlled in a straightforward manner. It has also been revealed that the type of IL makes impact on the EAP actuator performance by determining ion migration dynamics. Our actuators demonstrated large bending strains (up to 4%) under low voltages of 1-3V, which far exceeds the best performance of other EAP actuators reported in the literature. To underpin the molecular-level understanding of actuation mechanisms underlying the improved performance, we carried out in situ spectroscopy and in situ scattering experiments under actuation.

Proton-conducting membranes based on benzimidazole polymers for high-temperature PEM fuel cells. A chemical quest.

PubMed

Asensio, Juan Antonio; Sánchez, Eduardo M; Gómez-Romero, Pedro

2010-08-01

The development of high-temperature PEM fuel cells (working at 150-200 degrees C) is pursued worldwide in order to solve some of the problems of current cells based on Nafion (CO tolerance, improved kinetics, water management, etc.). Polybenzimidazole membranes nanoimpregnated with phosphoric acid have been studied as electrolytes in PEMFCs for more than a decade. Commercially available polybenzimidazole (PBI) has been the most extensively studied and used for this application in membranes doped with all sorts of strong inorganic acids. In addition to this well-known polymer we also review here studies on ABPBI and other polybenzimidazole type membranes. More recently, several copolymers and related derivatives have attracted many researchers' attention, adding variety to the field. Furthermore, besides phosphoric acid, many other strong inorganic acids, as well as alkaline electrolytes have been used to impregnate benzimidazole membranes and are analyzed here. Finally, we also review different hybrid materials based on polybenzimidazoles and several inorganic proton conductors such as heteropoly acids, as well as sulfonated derivatives of the polymers, all of which contribute to a quickly-developing field with many blooming results and useful potential which are the subject of this critical review (317 references).

Facile and scalable fabrication of polymer-ceramic composite electrolyte with high ceramic loadings

DOE PAGES

Pandian, Amaresh Samuthira; Chen, Xi Chelsea; Chen, Jihua; ...

2018-04-24

Solid state electrolytes are a promising alternative to flammable liquid electrolytes for high-energy lithium battery applications. In this work polymer-ceramic composite electrolyte membrane with high ceramic loading (greater than 60 vol%) is fabricated using a model polymer electrolyte poly(ethylene oxide) + lithium trifluoromethane sulfonate and a lithium-conducting ceramic powder. The effects of processing methods, choice of plasticizer and varying composition on ionic conductivity of the composite electrolyte are thoroughly investigated. The physical, structural and thermal properties of the composites are exhaustively characterized. We demonstrate that aqueous spray coating followed by hot pressing is a scalable and inexpensive technique to obtainmore » composite membranes that are amazingly dense and uniform. The ionic conductivity of composites fabricated using this protocol is at least one order of magnitude higher than those made by dry milling and solution casting. The introduction of tetraethylene glycol dimethyl ether further increases the ionic conductivity. The composite electrolyte's interfacial compatibility with metallic lithium and good cyclability is verified by constructing lithium symmetrical cells. As a result, a remarkable Li + transference number of 0.79 is discovered for the composite electrolyte.« less

Swelling kinetics and electrical charge transport in PEDOT:PSS thin films exposed to water vapor

NASA Astrophysics Data System (ADS)

Sarkar, Biporjoy; Jaiswal, Manu; Satapathy, Dillip K.

2018-06-01

We report the swelling kinetics and evolution of the electrical charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films subjected to water vapor. Polymer films swell by the diffusion of water vapor and are found to undergo structural relaxations. Upon exposure to water vapor, primarily the hygroscopic PSS shell, which surrounds the conducting PEDOT-rich cores, takes up water vapor and subsequently swells. We found that the degree of swelling largely depends on the PEDOT to PSS ratio. Swelling driven microscopic rearrangement of the conducting PEDOT-rich cores in the PSS matrix strongly influences the electrical charge transport of the polymer film. Swelling induced increase as well as decrease of electrical resistance are observed in polymer films having different PEDOT to PSS ratio. This anomalous charge transport behavior in PEDOT:PSS films is reconciled by taking into account the contrasting swelling behavior of the PSS and the conducting PEDOT-rich cores leading to spatial segregation of PSS in films with PSS as a minority phase and by a net increase in mean separation between conducting PEDOT-rich cores for films having abundance of PSS.

Colloidal polymer particles as catalyst carriers and phase transfer agents in multiphasic hydroformylation reactions.

PubMed

Peral, D; Stehl, D; Bibouche, B; Yu, H; Mardoukh, J; Schomäcker, R; Klitzing, R von; Vogt, D

2018-03-01

Colloidal particles have been used to covalently bind ligands for the heterogenization of homogeneous catalysts. The replacement of the covalent bonds by electrostatic interactions between particles and the catalyst could preserve the selectivity of a truly homogeneous catalytic process. Functionalized polymer particles with trimethylammonium moieties, dispersed in water, with a hydrophobic core and a hydrophilic shell have been synthesized by emulsion polymerization and have been thoroughly characterized. The ability of the particles with different monomer compositions to act as catalyst carriers has been studied. Finally, the colloidal dispersions have been applied as phase transfer agents in the multiphasic rhodium-catalyzed hydroformylation of 1-octene. The hydrodynamic radius of the particles has been shown to be around 100 nm, and a core-shell structure could be observed by atomic force microscopy. The polymer particles were proven to act as carriers for the water-soluble hydroformylation catalyst, due to electrostatic interaction between the functionalized particles bearing ammonium groups and the sulfonated ligands of the catalyst. The particles were stable under the hydroformylation conditions and the aqueous catalyst phase could be recycled three times. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhancement in Elastic Bending Rigidity of Polymer Loaded Reverse Microemulsions.

PubMed

Geethu, P M; Yadav, Indresh; Aswal, Vinod K; Satapathy, Dillip K

2017-11-14

Elastic bending rigidity of the surfactant shell is a crucial parameter which determines the phase behavior and stability of microemulsion droplets. For water-in-oil reverse microemulsions stabilized by AOT (sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate) surfactant, the elastic bending rigidity is close to thermal energy at room temperature (k B T) and can be modified by the presence of hydrophilic polymers. Here, we explore the influence of two polymers polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP), both having nearly same size (radius of gyration, R g ) but different dipole moment, on elastic bending rigidity of water-AOT-n-decane reverse microemulsions via estimating the percolation temperatures (T P ) and droplet radii using dielectric relaxation spectroscopy (DRS) and small-angle neutron scattering (SANS) techniques. Notably, an increase in T P is observed on introducing PEG and PVP polymers and is attributed to the adsorption of polymer chains onto the surfactant monolayer. The stability of the droplet phase of microemulsion after the incorporation of PEG and PVP polymers is confirmed by contrast matching SANS experiments. An enhancement in elastic bending rigidity of AOT surfactant shell amounting to ∼46% is observed upon incorporation of PVP into the droplet core, whereas for PEG addition, a smaller increase of about 17% is recorded. We conjecture that the considerable increase in elastic bending rigidity of the surfactant monolayer upon introducing PVP is because of the strong ion-dipole interaction between anionic AOT and dipoles present along the PVP polymer chains. Scaling exponents extracted from the temperature dependent electrical conductivity measurements and the frequency dependent scaling of conductivity at percolation indicate the dynamic nature of percolation for both pure and polymer loaded reverse microemulsions. The decrease in activation energy of percolation upon incorporating PEG and PVP polymer molecules also reflects the increased stability of microemulsion droplets against thermal fluctuations.

Aromatic fluorine compounds. XI. Replacement of chlorine by fluorine in halopyridines

USGS Publications Warehouse

Finger, G.C.; Starr, L.D.; Dickerson, D.R.; Gutowsky, H.S.; Hamer, J.

1963-01-01

The ??-halogenated pyridines react with potassium fluoride in various solvents to give replacement of the ??-halogen by fluorine. A 50% yield of 2-fluoropyridine was obtained from 2-chloropyridine by heating with potassium fluoride in dimethyl sulfone or tetramethylene sulfone for twenty-one days; 2-bromopyridine gave a similar yield with a heating period of only seven days. The ??-halogens of the polyhalopyridines undergo the exchange reaction more readily than do the halogens of the ??-monohalopyridines. The proposed structures of the fluoropyridines are supported by alternate syntheses and by n.m.r. studies.

Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

NASA Astrophysics Data System (ADS)

Sundararaman, Ramanathan

Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk MgO catalysts for decomposition of sulfones showed that these catalysts are effective in decomposing oxidized sulfur compounds such as dibenzothiophene sulfone and 3-methyl benzothiophene sulfone to biphenyl and isopropyl benzene respectively and SO2. Study of catalyst structure-activity relationship revealed that in the range of 40--140 nm of MgO, crystallite size plays a critical role on activity of the catalyst for sulfone decomposition. In testing other alkali oxides, it was demonstrated that CaO was effective as a reagent in decomposing oxidized sulfur compounds in a crude oil at a much lower temperature than used for MgO based catalyst. Preliminary data on potential regeneration scheme of spent CaO is also discussed.