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Lysozyme binding to poly(4-vinyl-N-alkylpyridinium bromide)

SILVA, Rubens A.; URZUA, Marcela D.; PETRI, Denise F. S.
Fonte: ACADEMIC PRESS INC ELSEVIER SCIENCE Publicador: ACADEMIC PRESS INC ELSEVIER SCIENCE
Tipo: Artigo de Revista Científica
ENG
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The adsorption behavior of polycations at ionic strengths (1) ranging from 0.001 to 0.1 onto silicon wafers was studied by means of ellipsometry, contact angle measurements and atomic force microscopy (AFM). Polycations chosen were bromide salts of poly(4-vinylpyridine) N-alkyl quaternized with linear aliphatic chains of 2 and 5 carbon atoms, QPVP-C2 and QPVP-C5, respectively. Under 1 0.001 the reduction of screening effects led to low adsorbed amounts of QPVP-C2 or QPVP-C5 (1.0 +/- 0.1 mg/m(2)), arising from the adsorption of extended chains. Upon increasing l to 0.1, screening effects led to conformational changes of polyelectrolyte chains ill Solution and to higher adsorbed amount values (1.9 +/- 0.2 mg/m(2)). Advancing contact angle theta(a) measurements performed with water drops onto QPVP-C2 and QPVP-C5 adsorbed layers varied from (45 +/- 2)degrees to (50 +/- 5)degrees, evidencing the exposure of both hydrophobic alkyl groups and charged moieties. The adsorption of lysozyme (LYZ) molecules to QPVP-C5 layers was more pronounced than to QPVP-C2 films. Antimicrobial effect of LYZ bound to QPVP-C2 or QPVP-C5 layers or to Si wafers was evaluated with enzymatic assays using Micrococcus luteus as Substrates. The adsorption behavior of QPVP-C2 and QPVP-C5 at the water-air interface was studied by means Of surface tension measurements. Only QPVP-C5 was able to reduce water Surface tension. Mixtures of LYZ and QPVP-C5 were more efficient in reducing Surface tension than pure LYZ solution...

Synthesis and characterization of ruthenium complexes immobilized on poly(4-vinylpyridine)

Hoffmann, M. T.; Lima Neto, B. S.; Massabni, A. M G; Franco, D. W.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 155-168
ENG
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The [Ru(NH3)5(H2O)]2+ and trans-[Ru(NH3)4SO2(H2O)]2+ complexes ions were immobilized on poly(4-vinylpyridine) (4-PVP) through reactions in aqueous solutions. The stability of the imobilized complexes was checked in aqueous solution in the pH 2.0-8.0 range. The number of pyridinic nitrogens in the polymer 4-PVP is 2.80±0.05 mmol/g according to nitrogen elemental analysis. Potentiometric titration experiments showed that the accessible nitrogen, in aqueous medium, was 0.94±0.02 mmol/g with a p Ka value of 7.4±0.2. In addition, ruthenium and sulfate analysis has demonstrated that about 15% of the accessible nitrogen sites are able to coordinate to the metal centers. The characterization of the immobilized complexes was made through diffuse electronic and infrared spectroscopies and differential pulse and cyclic voltammetries. © 1993 Plenum Publishing Corporation.

Cross linked Poly (4-Vinylpyridine-Ethylene Glycol Dimethacrylate) Used for Preconcentration of Cd(II) and its Determination by Flow Injection Flame Atomic Absorption Spectrometry

Teixeira Tarley, Cesar Ricardo; Botteon Farias, Natalia Cristina; Lima, Giovana de Fatima; Oliveira, Fernanda Midori de; Bonfilio, Rudy; Dragunski, Douglas Cardoso; Clausen, Debora Nobile; Segatelli, Mariana Gava
Fonte: Aoac Int Publicador: Aoac Int
Tipo: Artigo de Revista Científica Formato: 605-611
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The main purpose of this research was to synthesize crosslinked poly(4-vinylpyridine-ethylene glycol dimethacrylate) and evaluate its feasibility for highly sensitive and selective determination of Cd in water samples by using flow injection flame atomic absorption spectrometry. The crosslinked polymer, prepared by bulk polymerization, was characterized by FTIR spectrometry and scanning electron microscopy. The flow injection solid-phase method was based on preconcentration of 20.0 mL of sample through 100 mg of the polymer packed into a minicolumn at pH 8.25 using a flow rate of 6.0 mL/min, followed by elution with 1.0 M HNO3. The sample solution parameters influencing the preconcentration behavior of Cd ions, such as pH, buffer concentration, and flow rate, were simultaneously studied and optimized using? Doehlert matrix. Values of 0.10 mu g/L, 2.0-210 mu g/L, 32.3, 18/h, 9.7/min, and 0.62 mL were obtained for LOD, linear range, preconcentration factor, sample throughput, concentration efficiency, and consumption index, respectively. The effect of the presence of the inorganic cations Pb(II)...

Estudo de novos suportes para catalisadores de ziegler-natta

Soraya Jerico de Carvalho
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/12/1992 PT
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Neste trabalho o tetracloreto de titânio - TiCl4- foi heterogeneizado em suportes alternativos com o objetivo de se obter novos catalisadores de Ziegler-Natta heterogeneizados. Os suportes orgânicos utilizados foram: poli(propileno) atático -aPP, borracha natural -NR, poli(cloreto de vinila) -PVC, poli(4-vinilpiridina) P4VP- com 2% e 25% de divinilbenzeno (DVB) e o polímero de Merrifield. O aPP, a NR e o PVC foram funcionalizados através de cloração e o polímero de Merrifield foi funcionalizado com ciclopentadieno. Os cataIisadores obtidos foram testados na polimerização de olefinas. Entre os catalisadores heterogeneizados nos suportes poliméricos clorados, o que apresentou a melhor atividade frente à polimerização de etileno foi o sistema baseado em aPP clorado (20,7 kg PE/mol Ti.h.bar). O TiCl4 heterogeneizado nos suportes poliméricos não-clorados apresentou baixa atividade. O melhor destes sistemas foi o de P4VP com 25% DVB (7,9 kg PE/mol Ti.h.bar). As massas molares médias viscosimétricas -v- dos poli(etilenos) -PE- sintetizados variaram de 300 a 1500 kg/moI, dependendo do sistema. Os suportes inorgânicos estudados foram a crisotila e o óxido de titânio - TiO2. A atividade do TiCl4 heterogeneizado na crisotila...

Metalopolímero de pentacianoferrato e poli(4-vinilpiridina) : síntese, caracterização e aplicação na produção de estruturas automontadas; Pentacyanoferrate and poly(4-vinylpyridine) metallopolymer : synthesis, characterization and application to the production of self-assembled structures

Sergio Augusto Venturinelli Jannuzzi
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/12/2011 PT
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O presente trabalho ocupa-se da síntese, caracterização e aplicação de um material híbrido orgânico-inorgânico em que o bloco orgânico é o polímero poli(4-vinilpiridina) e o bloco inorgânico é o pentacianoferrato(II) de sódio. A primeira parte trata da influência do polímero nas propriedades do complexo, e vice-versa. A segunda parte ilustra a aplicação do metalopolímero na produção de estruturas análogas ao azul da Prússia (AP) pela reação de Fe com as unidades pentacianoferrato. A banda de transferência de carga metal-ligante do pentacianoferrato do metalopolímero em solução desloca-se para energias menores na medida em que aumenta a fração de meros livres da cadeia polimérica, indicando que a fração do bloco orgânico modula a polaridade do ambiente químico do complexo. Por outro lado, a crescente quantidade de complexo ligado às cadeias poliméricas aumenta viscosidade das soluções de metalopolímeros, evidenciando que o pentacianoferrato expande o novelo macromolecular. Estruturas tipo azul da Prússia sintetizadas a partir do metalopolímero exibem elevada estabilidade coloidal quando comparadas aos compostos isentos de polímero e apresentam banda de intervalência em menores energias do que o frequentemente reportado para esse tipo de estrutura...

Complexos de poli(vinilpiridinas) / cobre e tiocianato

Santana, Adriana Lídia
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Tese de Doutorado Formato: 128 p.| il., grafs., tabs.
POR
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2009; Neste trabalho estudo-se a formação de complexos de poli(vinilpiridinas) com íons cobre e tiocianato, e de filmes passivantes sobre eletrodo de cobre em meio contendo poli(2-vinilpiridina) [P2VP] ou poli(4-vinilpiridina) [P4VP] e tiocianato. Os complexos foram caracterizados por espectroscopia na região do infravermelho, termogravimetria (TG) e calorimetria exploratória diferencial (DSC). A interação polímero/metal ocorre pela formação de ligação entre o íon Cu(II) e o átomo de nitrogênio do anel, bem como pela coordenação do ânion tiocianato através do átomo de nitrogênio. A oxidação do cobre resulta na formação de compostos de coordenação depositados sobre a superfície do cobre na forma de filmes, que apresentam características dependentes da estrutura do polímero. Com P2VP foram obtidos complexos com cobre monovalente, enquanto que em meio de P4VP foi observada a formação de complexos com cobre divalente e tiocianato coordenado através do átomo de nitrogênio. Os complexos sintetizados eletroquimicamente e pela mistura física dos componentes mostraram propriedades com relação á estrutura eletrônica...

Interaction of poly(4-vinylpyridine) with copper surfaces: electrochemical, thermal and spectroscopic studies

Giacomelli,Cristiano; Giacomelli,Fernando Carlos; Santana,Adriana Lídia; Schmidt,Vanessa; Pires,Alfredo Tiburcio Nunes; Bertolino,José Roberto; Spinelli,Almir
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
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The interaction of poly(4-vinylpyridine) (P4VP) and thiocyanate ions with copper in acid solutions was studied by cyclic voltammetry, thermogravimetry, elemental analysis and infrared spectroscopy. It is shown that at ca. -0.45 V/SCE the electrogenerated Cu(I) ions at the surface of a copper electrode induce a complexing reaction with P4VP and SCN- both present in solution. The resulting electroactive polymer-complex grows onto the electrode surface as a film, and the metallic center is further oxidized to Cu(II) in a subsequent step at ca. -0.23 V/SCE. According to thermogravimetric results, the polymer-complex is less thermally-stable than P4VP as evidenced by the lowering in the initial temperature of degradation from ca. 400 ºC (P4VP) to ca. 200 ºC (complex). The elemental analysis revealed a chemical composition of 2:1:2 for P4VP:Cu:SCN, and the infrared spectra indicated that the complex comprises a copper metallic center coordinated with nitrogen pyridinic rings (P4VP) and thiocyanate ions.

Protective effect of poly(4-Vinylpyridine) containing surface films to the corrosion of copper

Giacomelli,Cristiano; Giacomelli,Fernando Carlos; Schmidt,Vanessa; Santana,Adriana Lídia; Pires,Alfredo Tiburcio Nunes; Bertolino,José Roberto; Spinelli,Almir
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2005 EN
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We report here on the ability of poly(4-vinylpyridine) (P4VP) films to improve the copper corrosion properties in 0.1 mol L-1 H2SO4. Films formed by Cu(P4VP)2(SCN)2 macromecular-complex were electrochemically or spontaneously (by immersion) grown onto copper surfaces in 3% acetic acid, 0.1 mol L-1 KSCN and P4VP containing solutions. Imaging and electrochemical techniques were employed to characterize the film morphology and evaluate its effect on the copper corrosion, respectively. A substantial increase in corrosion resistance of copper samples spontaneously coated by P4VP films was found in comparison to the uncoated ones. The optimum conditions for spontaneous growth comprise a 3 - 4 h immersion period in a 0.1 mol L-1 P4VP containing solution. Inhibition efficiencies (IE) of 94 - 98% were recorded by employing this methodology. For electrochemically grown P4VP films, the IE was 70 - 85%.

Characterization of poly-{trans-[RuCl2(vpy)4 ]-styrene-4-vinylpyridine} impregnated with silver nanoparticles in non aqueous medium

Segala,Karen; Dutra,Rosilene L.; Oliveira,Eric N. de; Rossi,Liane M.; Matos,Jivaldo R.; Paula,Marcos M. S.; Franco,César V.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 EN
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The synthesis and characterization of a new polymeric material composed of poly-{trans-[RuCl2(vpy)4 ]-styrene-4-vinylpyridine} impregnated with silver nanoparticles are here described. This material was obtained by a non aqueous polymerization reaction involving trans-[RuCl2(vpy)4], styrene (sty) and 4-vinylpyridine (4-vpy), using benzoyl peroxide as initiator. The silver particles nanometric dimensions were confirmed by transmission electron microscopy (TEM) and UV-visible spectroscopy. The terpolymer morphology was characterized by scanning electron microscopy (SEM). Thermal properties were analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The antimicrobial action of the polymer impregnated with silver nanoparticles was evaluated by the use of Gram positive and Gram negative microorganisms, Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), respectively. The antimicrobial activity of the terpolymer with silver nanoparticles was confirmed by the presence of a bacterial growth inhibition halo in seeded culture media.

In situ and ex situ preparations of ZnO/poly-{trans-[RuCl2(vpy)4]/styrene} nanocomposites

Segala,Karen; Dutra,Rosilene L.; Franco,César V.; Pereira,Angela S.; Trindadeb,Tito
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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Nanosized semiconductor particles are of great scientific and technological interest because of their size-dependent electronic and optical properties. Semiconductor nanocrystals have been investigated, for example, as nano-fillers for diverse polymer matrices in order to produce new optically active materials. Here we report, for the first time, results concerning the preparation of nanocomposites made of ZnO nanocrystals (NCs) incorporated in the co-polymer poly-{trans-[RuCl2(vpy)4]/sty (sty = styrene and vpy = 4-vinylpyridine). In a first step, the co-polymer was prepared by reaction of trans-[RuCl2(vpy)4] with styrene. Then, organically capped ZnO NCs and poly-{trans-[RuCl2(vpy)4]/sty} were mixed in CH2Cl2 to produce cast films of the nanocomposites after evaporation of the solvent (ex situ method). The properties of these materials were compared to those of nanocomposites obtained by in situ polymerization in the presence of ZnO NCs.

Designing surfaces that kill bacteria on contact

Tiller, Joerg C.; Liao, Chun-Jen; Lewis, Kim; Klibanov, Alexander M.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Poly(4-vinyl-N-alkylpyridinium bromide) was covalently attached to glass slides to create a surface that kills airborne bacteria on contact. The antibacterial properties were assessed by spraying aqueous suspensions of bacterial cells on the surface, followed by air drying and counting the number of cells remaining viable (i.e., capable of growing colonies). Amino glass slides were acylated with acryloyl chloride, copolymerized with 4-vinylpyridine, and N-alkylated with different alkyl bromides (from propyl to hexadecyl). The resultant surfaces, depending on the alkyl group, were able to kill up to 94 ± 4% of Staphylococcus aureus cells sprayed on them. A surface alternatively created by attaching poly(4-vinylpyridine) to a glass slide and alkylating it with hexyl bromide killed 94 ± 3% of the deposited S. aureus cells. On surfaces modified with N-hexylated poly(4-vinylpyridine), the numbers of viable cells of another Gram-positive bacterium, Staphylococcus epidermidis, as well as of the Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, dropped more than 100-fold compared with the original amino glass. In contrast, the number of viable bacterial cells did not decline significantly after spraying on such common materials as ceramics...

Antagonistic activity of poly (4-vinylpyridine-N-oxide) to the inhibition of viral interferon induction by asbestos fibres.

Hahon, N; Booth, J A; Eckert, H L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1977 EN
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The depressive activity of both serpentine (Canadian and Rhodesian chrysotiles) and amphibole (amosite, crocidolite, and anthophyllite) asbestos fibres on interferon induction by influenza virus was significantly diminished or abolished completely when either asbestos fibres or LLC-MK2 cell monolayers were pretreated with poly(4-vinylpyridine-N-oxide). Maximal antagonistic activity of the polymer was time and concentration dependent. Pretreating asbestos fibres with the polymer was more rapid and effective in encouraging viral interferon synthesis than pretreating cell monolayers. Virus multiplication in the presence of asbestos fibre-treated cell monolayers attained a twofold higher level than that noted in normal cell monolayers or those containing polymer-pretreated asbestos fibres. These findings were related to the suppression of interferon production.

Hydrogenation of quinoline by ruthenium nanoparticles immobilized on poly(4-vinylpyridine)

Sánchez-Delgado, Roberto A.; Machalaba, Nataliya; Ng-a-qui, Nkechia
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/2007 EN
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A series of catalysts composed of ruthenium nanoparticles immobilized on poly(4-vinylpyridine) was prepared by NaBH4 reduction of RuCl3.3H2O in methanol in the presence of the polymer; TEM measurements of a 10 wt % Ru/P4VPy material indicate that ruthenium particles of 1-2 nm predominate. This catalyst is efficient for the selective hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline at 100–120 ºC and 30–40 bar H2. The activity increases with hydrogen pressure up to 40 bar but is essentially independent of quinoline concentration. Polar solvents, triethylamine, and acetic acid enhance catalytic performance, suggesting an ionic mechanism involving heterolytic hydrogen activation.

Electrospinning and characterization of supramolecular poly(4-vinyl pyridine)-small molecule complexes

Wang, Xiaoxiao
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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La chimie supramoléculaire est basée sur l'assemblage non covalent de blocs simples, des petites molécules aux polymères, pour synthétiser des matériaux fonctionnels ou complexes. La poly(4-vinylpyridine) (P4VP) est l'une des composantes supramoléculaires les plus utilisées en raison de sa chaîne latérale composée d’une pyridine pouvant interagir avec de nombreuses espèces, telles que les petites molécules monofonctionnelles et bifonctionnelles, grâce à divers types d'interactions. Dans cette thèse, des assemblages supramoléculaires de P4VP interagissant par liaisons hydrogène avec de petites molécules sont étudiés, en ayant comme objectifs de faciliter l'électrofilage de polymères et de mieux comprendre et d'optimiser la photoréponse des matériaux contenant des dérivés d'azobenzène. Une nouvelle approche est proposée afin d'élargir l'applicabilité de l'électrofilage, une technique courante pour produire des nanofibres. À cet effet, un complexe entre la P4VP et un agent de réticulation bifonctionnel capable de former deux liaisons hydrogène, le 4,4'-biphénol (BiOH), a été préparé pour faciliter le processus d’électrofilage des solutions de P4VP. Pour mieux comprendre ce complexe, une nouvelle méthode de spectroscopie infrarouge (IR) a d'abord été développée pour quantifier l'étendue de la complexation. Elle permet de déterminer un paramètre clé...

Oligomerização e telemirização de butadieno na presença de catalizadores de niquel, ferro e paladio, ancorados em polimeros organicos

Francisco Santos Dias
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/03/1987 PT
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Níquel, ferro e paládio foram ancorados em poli(vinilpiridinas) e em poli(estireno/divinilbenzeno) funcionalizado com 2,2'-bipiridila. Os sistemas catalíticos de níquel foram altamente ativos e seletivos para a ciclotrimerização de butadieno a 1,5,9-ciclododecatrieno (CDT; 62,3 a 91,7%) . As reações de oligomerização de butadieno na presença de ca- talisadores heterogeneizados de ferro foram lentas, semelhantes aos sistemas homogêneos correspondentes. As poli(vinilpiridinas) contendo ferro apresentaram baixa seletividade para a oligomerização. No entanto, ferro ancorado em poli(estireno/divinilbenzeno) funcionalizado com 2,2'-bipiridila, levou somente à formação dos ciclodímeros 4-vinilciclohexeno (VCH, 41%) e ciclooctadieno-1,5 (COD, 37%). A telomerização de bu- tadieno com metanol na presença de polímeros contendo paládio(II) somente foi possível com a adição de trifenilfosfina, fornecendo uma relação de produtos que difere da reação catalítica em fase homogênea. Em todos os casos, certa quantidade do metal foi lixiviada dos polímeros durante as reações e não foi possível a reciclagem dos catalisadores, com excessão de poli(4-vinilpiridina) níquel. A partir dos resultados das conversões molares globais e das seletividades obtidas são discutidos os prováveis mecanismos da catálise...

Counteraction of poly(4-vinylpyridine-n-oxide) on the depression of viral interferon induction by coal dust.

Hahon, N
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1976 EN
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The depressive activity of coal dust on interferon induction by influenza was markedly subverted when either coal dust or LLC-MK2 cell monolayers were pretreated with poly (4-vinylpyridine-N-oside). The polymer alone neither induced interferon synthesis, inhibited viral induction of interferon, influenced viral multiplication, nor affected cellular-induced resistance by interferon. Absorption of the polymer to coal dust not only occurred at a more rapid rate than to cell monolayers, but also less polymer was required to pretreat coal dust than cell monolayers to achieve comparable amelioration of interferon production. The polymer effectively negated the adverse activity of coal dust particles, irrespective of the latter's size (is less than 2.0 to 74.0 mum). Virus multiplication in the presence of coal dust=treated cell monolayers attained a level that was twofol higher than that noted with either polymer-pretreated coal dust or polymer-pretreated cell monolayers. Interferon production was almost completely inhibited in the presence of coal dust; pretreating coal dust or cells with the polymer abrogated this inhibitory activity of coal dust. It is tentatively suggested that coal dust particles per se directly interact with cell membranes to subvert interferon induction and that the formation of an absorbed polymerlayer on these complexes prevents their interaction.

Blends containing amphiphilic polymers. V. Compatibilization of N-alkylitaconamic acid-co-styrene copolymers with interacting polymers

Gargallo, Ligia; Leiva, Angel; Radic, Deodato; González Nilo, Fernando; Sandoval, Claudia; Urzúa, Marcela
Fonte: JOHN WILEY Publicador: JOHN WILEY
Tipo: Artículo de revista
EN
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The phase behavior of blends containing N-alkylitaconamic acid-co-styrene copolymers (NAIA-co-S) with poly(N-vinyl-2-pyrrolidone) (PVY) of two different weight average molecular weights (M-w($) over bar), poly(2-vinylpyridine) (P2VPy) and poly(4-vinylpyridine) (P4VPy), was analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. Copolymers containing 80% S are miscible with PVT10, PVP24, and P4VPy over the whole range of composition. In the case of blends with P2VPy, miscibility is observed only for the first three members of the series, i.e., NEIA-co-S, NPIA-co-S, and NBIA-co-S. For copolymers containing hexyl to dodecyl moieties, phase separation is observed in blends with P2VPy. Copolymers containing 50% S are miscible over the whole range of composition irrespective of the homopolymer and the length of the side chain of the itaconamic moiety of the copolymer. This behavior is interpreted in terms of steric hindrance, in the sense that the copolymers with long side chains are not able to interact with the nitrogen of P2VPy because of the position in the aromatic ring. The interactions between copolymers and homopolymers are discussed in terms of specific interactions like hydrogen bonds between the itaconamic moiety and the different functional groups of the homopolymers...

Factors Affecting the Electrochemical Responses of Metal Complexes at Pyrolytic Graphite Electrodes Coated with Films of Poly(4-Vinylpyridine)

Oyama, Noboru; Anson, Fred C.
Fonte: Instituto de Tecnologia da Califórnia Publicador: Instituto de Tecnologia da Califórnia
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /03/1980
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Electrochemical responses from the reduction of RuIII (edta) coordinatedto films of high molecular weight poly(4-vinylpyridine) on pyrolytic graphiteelectrodes were studied as functions of film thickness, temperature, supportingelectrolyte composition, and solvent. Responses at filmed electrodes from metalcomplexes that do not coordinate to the films were also examined. With filmsthicker than ca. 1000Å, the current responses are limited by the rates of molecularmotions within the films. Penetration of counterions, segmental motion ofsections of the polymer chains, and juxtapositioning of pairs of attached metalcomplexes to facilitate intercomplex electron transfer within the film or combinationsof the three are suggested as likely current limiting processes.

Adsorbed Layer Structure of a Weak Polyelectrolyte Studied by Colloidal Probe Microscopy and QCM-D as a Function of pH and Ionic Strength

Notley, Shannon M; Biggs, Simon; Craig, Vincent; Wagberg, Lars
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
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The adsorbed layer structure of a weak polyelectrolyte poly(2- vinylpyridine), on silica and mica, has been studied using colloidal probe microscopy (CPM) and the quartz crystal microbalance (QCM-D). The adsorbed layer structure was found to be highly dependent on both the solution conditions from which it was adsorbed and the molecular weight. Conditions were altered to favour both flat adsorbed layers and the development of significant steric layers. The structural reconformation of the large steric layer was furthermore studied as a function of pH. The equilibrium interaction force, measured using CPM as a function of surface separation, was used to determine the relative extension of the polyelectrolyte away from the interface. At low pH (3.2) and high ionic strength, the adsorbed polyelectrolyte molecules adopt a highly extended conformation; as the pH is increased (to 4.6 then to 5.5) the polymer chains collapse progressively towards the interface. Reversal of this pH cycle causes a re-protonation of the adsorbed polymers and highlights the finite timescale for this process to occur. The kinetics of this process was measured from the amount of trapped solvent within the polyelectrolyte layer as determined from the QCM-D. Upon decrease in pH...

Effect of Iodide Ions on Corrosion Inhibition of Mild Steel in 0.5 M H2SO4 by Poly(4-Vinylpyridine)

Larabi,Lahcène; Harek,Yahia
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2004 FR
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The effect of iodide ions on the corrosion inhibition of mild steel in 0.5 M sulfuric acid in the presence of poly(4-vinylpyridine) (p4vp) was studied by weight loss and different electrochemical techniques such as electrochemical impedance spectroscopy, potentiodynamic polarization and polarization resistance measurements. The obtained results showed that poly(4-vinylpyridine) effectively reduces the corrosion rate of mild steel. The addition of potassium iodide (KI) enhanced the inhibition efficiency (P%). The synergism parameter (Sp) calculated from inhibition efficiency was found to be greater than unity, suggesting that the phenomenon of synergism exists between P4VP and iodide ions. The adsorption of p4vp alone and in combination with KI followed Frumkin adsorption isotherm. The effect of temperature indicated that the inhibition efficiency of p4vp decreases with increasing temperature. Study of temperature effect showed also that inhibition efficiency of (P4VP + KI) does not depend on temperature. The apparent activation energies in the absence and in the presence of P4Vp and ( P4VP + KI ) were determined.