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  • Wiley-Blackwell  (51)
  • American Physical Society (APS)  (17)
  • Molecular Diversity Preservation International (MDPI)
  • American Association for the Advancement of Science (AAAS)
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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 351-360 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intrisic viscosity [η] of poly(vinyl alcohol) (PVA) was determined in aqueous solutions with various concentrations cb of borax (Na2B4O7) as functions of molecular weight M and concentration cs of NaCl as an added salt. Polyelectrolyte viscosity behaviour was observed for the systems containing both borax and NaCl, due to the complexation with negatively charged borate ions B(OH)-4 · [η] changes depending on the ionic strength I. It was found that the Stock-mayer-Fixman treatment for the molecular-weight dependence of [η] is valid in the lower molecular-weight range (M 〈 105), even though the present PVA chain contains some intrachain crosslinks. Theta conditions can be attained at an appropriate concentration cs Θ of NaCl. The value of cs Θ is dependent on cb, but the conformational parameter from the Stockmayer-Fixman treatment K0 is almost independent of cb. The effect of intrachain crosslinks becomes evident only as a considerably large negative value for the excluded volume parameter B at infinite ionic strength. In addition, the electrostatic part of the expansion factor α3e was found to be linearly correlated to a reduced parameter (M/I)1/2 for all cb systems, from the slope of which the charge density was estimated.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 167-172 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity behavior of aqueous poly(vinyl alcohol) (PVA)-borax-NaCl systems was investigated. The intrinsic viscosity [η] of PVA in borax solution increases with increasing borax concentration. In solutions containing both borax and NaCl, on the other hand, [η] decreases with increasing concentration of NaCl, and at high NaCl concentration phase separation is observed. In the absence of borax, [η] is nearly independent of the NaCl concentration. These results are interpreted in terms of a limited chain expansion due to charges and intrachain crosslinks simultaneously introduced in the PVA chain when the chain is complexed with negatively charged tetrahedral borate ions. The crosslinking density was estimated from the intrinsic viscosity [η]∞ at infinite ionic strength using the Kuhn and Majer equation.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2547-2556 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ten fractions of poly(allylammonium chloride) were investigated at 25°C in sodium chloride solutions of various concentrations, cs, by viscosity and light scattering techniques. The molecular weight (Mw)-intrinsic viscosity [η] relationships were established at four NaCl concentrations. The unperturbed dimensions estimated from the Stockmayer-Fixman plot are independent of cs. The second virial coefficient A2 and the excluded volume parameter B as well as [η] were found to be proportional to cS-1/2 and to have negative values in the limit of infinite cs. In addition, it was found that the electrostatic part of the expansion factor can be expressed in terms of a reduced parameter (Mw/cs)1/2 in a fairly wide range of Mw and cs.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 431-435 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of stereoregularity on the low-temperature relaxation processes were studied by dynamic mechanical measurements on isotactic and syndiotactic polyisobutyl methacrylates (iso-PiBMA and syn-PiBMA). The α, β, and γ relaxation processes were observed in both stereoregular forms. Both the α, and β loss peaks were at lower temperatures for iso-PiBMA than for syn-PiBMA. The γ loss peak was observed at about -155°C at 30 Hz for both forms, and the apparent activation energy of this process was same for both samples within experimental error (6.7 ± 0.5 kcal/mole). It was reduced from these results that the α and β processes are both considerably influenced by the isotactic configuration but the γ process is not.
    Additional Material: 2 Ill.
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  • 5
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 305-315 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Photosynthetic ATP accumulation was shown in the presence of exogenous ADP plus orthophosphate on illumination to the intact cells of a strain of thermophilic blue-green algae isolated from Matsue hot springs, Mastigocladus sp. Kinetic studies of various effectors on the ATP accumulation proved that the ATP synthesis depends mainly on the cyclic photophosphorylation system around photosystem I (PS-I) in the algal cells. The temperature and pH optima for the accumulation were found at 45°C and pH 7.5. Maximum yield was obtained with light intensity higher than 15 mW/cm2. Borate ion exerted pronounced enhancement on the ATP synthesis. With a continuous reactor at a flow rate of 1 ml/hr at 45°C and pH 7.5, efficient photoconversion of ADP (2mM, at substrate reservoir) to ATP (1mM, at product outlet) has been maintained for a period of 2.5 days, though the efficiency has decreased in a further 2-day period to the level of 0.5mM ATP/9.5 h of residence time.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 136 (1933), S. 129-132 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1629-1640 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The sorption properties of atactic polypropylene (APP) and isotactic polypropylene (IPP) were studied by equilibrium sorption of various organic solvents. The variation of the Flory-Huggins interaction parameter χ for the APP-CCl4 system at 25°C was expressed as a function of the volume fraction v2 of polymer by the relation: x = 0.113 exp {1.879 v2}. The average molecular weight Mc of the polymer chains between successive crystallites for IPP subjected to different thermal treatments was calculated to be 250 to 350 by the equation of Flory and Rehner. From the variation of Mc with solvent concentration, we estimated the number fraction of polymer chains actually contributing to elastic deformation. The clustering function for solvent in the polymer calculated by the method of Zimm and Lundberg decreased linearly from a positive value to -1 with increasing solvent concentration. Clustering of solvent molecules was found to occur more easily in APP than in IPP.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 233-240 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Potentiometric titration in various 1-1 salt solutions was carried out to study the dissociation behavior of the poly(allylammonium) cation (PAAH+). The titration curves show that proton release from cationic PAAH+ is markedly suppressed by addition of simple salt and depends on the counterion species. From an analysis of the titration curves it is found that the electrostatic free energy change ΔGel upon the proton release is negative in all systems examined, and its absolute value decreases with increasing ionic strength of the medium. Also, at a constant added salt concentration (0.1 mol L-1) ΔGel depends significantly on the counterion species added and increases in the order $\[ {\rm ClO}_{\rm 4}^ - 〉 {\rm NO}_3^ - 〉 {\rm Cl}^ - 〉 {\rm Br}^ - 〉 {\rm SCN}^ - 〉 {\rm I}^ - . \]$ The value of ΔGel correlates well with the electron donor constant En of the counterions. The dissociation behavior of PAAH+ is discussed in terms of electrostatic interaction among the ionized groups on the chain, the charge shielding effect, and the ion-solvent interaction of the added counterions.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0887-6266
    Keywords: association of hydrophobic counterions in aqueous poly(allylammonium) chloride ; hydrophobicity and steric effect of alkyl groups on association of p-n-propylbenzenesulfonate and p-iso-propylbenzenesulfonate ions ; poly(allylammonium) cation ; conformation change and precipitation of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrophobic association behavior of p-propylbenzenesulfonate ions (n-PBS- and iso-PBS-) around poly(allylammonium) cation (PAAH+ was studied by absorption and 1H nuclear magnetic resonance (NMR) spectroscopy. In the presence of PAAH+Cl-, the broadening (hypochromism) of absorption band of PBS- were observed. In addition, all 1H NMR signals of PBS- exhibited up-field shift which resulted from the intermolecular ring current shift. These results indicate the hydrophobic association of negative PBS- around PAAH+. The hydrophobic association arises from the accumulation of counterions around the polyion, and is stabilized by the hydrophobic interaction between propyl groups and the stacking interaction between benzene rings. The association of iso-PBS- ions is rather weaker than that of n-PBS-, suggesting that the steric hindrance of isopropyl groups prevents an effective association of hydrophobic counterions. Furthermore, through viscosity and Cl- activity measurements, it was found that the binding of associated PBS-,s to PAAH+ causes the change of its surroundings to hydrophobic character and its conformation. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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