Temperature Dependence of Viscosities and Potentiometric Titration Behavior of Poly(N-vinylimidazole) in Aqueous Salt Solutions

Sakurai, Masaru; Imai, Takateru; Yamashita, Fumitaka; Nakamura, Kunio; Komatsu, Tsuyoshi

doi:10.1295/polymj.26.658

Cited by 12 publications

(14 citation statements)

References 6 publications

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“…With strongly bonded counteranions such as chloride, the characteristic ratio of protonated sPVI is about the same as that of uncharged sPVI, whereas it is larger for loosely bonded counteranions 18. In some electrolyte solutions, hydrogen bonds between protonated and unprotonated rings cause coil contraction at low α values, and so the viscosity of sPVI, instead of increasing with ionization as usual, decreases for low α values and increases upon further protonation 14, 16, 17. A two‐step protonation mechanism has been proposed to explain potentiometric titrations of sPVI in organic solvents and in aqueous solutions of some electrolytes, and it has been related to conformational changes taking place over the course of titration 17…”

Section: Introductionmentioning

confidence: 99%

“…The pH range of ionization of a hydrogel is important in some of its applications (e.g., pH‐triggerable devices) and depends on many intrinsic and extrinsic factors that we intend to analyze in this work. The presence of imidazole groups in histidine has led to a large number of studies on its basicity in systems of biological importance and in soluble poly( N ‐vinylimidazole) (sPVI) samples 14–18. Metal‐ion uptake by hPVI9, 10, 13 depends on protonation, and the relationship between both processes has been previously reported.…”

Section: Introductionmentioning

confidence: 99%

“…The acid–base properties of soluble polymers, measured by p K a , have been broadly studied,14–31 and a few of these studies have been focused on sPVI 14–18. On the contrary, studies on p K a of swellable crosslinked polymers in centimeter‐size slab gel samples32–37 or microspheres38–40 are rarely found, and as far as we know, there is no study with respect to the basicity of hPVI.…”

Section: Introductionmentioning

confidence: 99%

“…The unusually large entropic effect has been attributed to specific interactions of neutral and protonated imidazole groups with chloride anions 15. The protonation of sPVI is influenced by the anion of the protonating acid and supporting electrolyte 14–18. With strongly bonded counteranions such as chloride, the characteristic ratio of protonated sPVI is about the same as that of uncharged sPVI, whereas it is larger for loosely bonded counteranions 18.…”

Section: Introductionmentioning

confidence: 99%

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Factors driving the protonation of poly(N‐vinylimidazole) hydrogels

Molina

Gómez-Antón

Piérola

2004

J Polym Sci B Polym Phys

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Poly(N‐vinylimidazole) hydrogels immersed in aqueous acid solutions produce an increment in the pH of the bath because of proton uptake by basic imidazole moieties, leading to hydrogel protonation. Both kinetic and equilibrium measurements of the pH of the bath have been performed under a variety of conditions and with different hydrogel samples. The kinetics of the xerogel protonation process (which includes solvent and titrant diffusion, the true protonation reaction or ion–dipole association, and the polymer relaxation to a new conformation) are mostly driven by the size of the hydrogel sample, whereas other magnitudes, such as the initial pH, the effective polymer concentration, and the network structure, governed by the crosslinker ratio and total comonomer concentration in the feeding, have a minor influence. pKa changes with the degree of protonation (α), delimitating two different regions: (1) a broad α range in which pKa decreases with increasing α but less pronouncedly with increasing ionic strength and (2) an α range close to α = 1 in which pKa decreases abruptly, more markedly with sulfate than with chloride counteranions and with larger ionic strengths. In the first region, pKa is determined by repulsive electrostatic interactions and so is larger for titration with H2SO4 than with HCl and increases as the effective polymer concentration and ionic strength increase. Two steps (i.e., two protonation sites) can be observed in the titration curves, the second one corresponding to abrupt changes in the basicity of the second pKa‐versus‐α region. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2294–2307, 2004

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Factors driving the protonation of poly(N‐vinylimidazole) hydrogels

Molina

Gómez-Antón

Piérola

2004

J Polym Sci B Polym Phys

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“…1-Vinylimidazole moiety contains two active centers: a lone electron pair of N atoms, which exhibits donating properties, and an unsaturated π-system of heterocycle, which is characterized by withdrawing properties [14,15]. Such combination of acidic and basic units in a polymer chain imparts the macromolecules highly interesting acid-base and complexing properties [16].…”

Section: Introductionmentioning

confidence: 99%

Terpolymers of N-vinylpyrrolidinone and 1-vinylimidazole as new supports for palladium nanocluster catalysts

et al. 2011

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Two terpolymers of styrene, divinylbenzene, and 1-vinylimidazole (S/DVB/VI) or N-vinylpyrrolidinone (S/DVB/NVP) were prepared by radical polymerization. Palladium nanoparticle catalyst has been "heterogenized" by anchoring to these polymers the [PdCl 2 (PhCN) 2 ] complex via ligand exchange reaction. The formation of coordination bond between S/DVB/VI, S/DVB/NVP terpolymers and Pd 2+ ions was studied using infrared and XPS. Immobilized palladium complex was reduced during hydrogenation reaction or by reaction with sodium borohydride. Characterization of polymer supports and palladium catalysts has involved the measurements of the structural parameters in the dry state by the nitrogen BET adsorption, X-ray photoelectron spectroscopy (XPS), AAS spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Both the catalytic systems were found efficient in the hydrogenation of cinnamaldehyde. The stability and a good recycling efficiency of these catalysts make them useful for prolonged use. The factors influencing selectivity of supported catalysts were discussed. The results offer the possibility of using these terpolymers for the immobilization of metal complex catalysts for hydrogenation and other catalytic reactions.

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Concentration Dependence of the Viscosity of Dilute Polymer Solutions: Huggins and Schulz‐Blaschke Constants

Schöff

1999

The Wiley Database of Polymer Properties

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Temperature Dependence of Viscosities and Potentiometric Titration Behavior of Poly(N-vinylimidazole) in Aqueous Salt Solutions

Cited by 12 publications

References 6 publications

Factors driving the protonation of poly(N‐vinylimidazole) hydrogels

Factors driving the protonation of poly(N‐vinylimidazole) hydrogels

Terpolymers of N-vinylpyrrolidinone and 1-vinylimidazole as new supports for palladium nanocluster catalysts

Concentration Dependence of the Viscosity of Dilute Polymer Solutions: Huggins and Schulz‐Blaschke Constants

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