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  • 1990-1994  (9)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 865-871 
    ISSN: 0392-6737
    Keywords: Disperse systems ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The phase diagram of the ternary system,i.e. poly(diallyldimethylammonium chloride), poly(acrylic acid, sodium salt), and water was investigated by varying the molecular weight of the components. In general, a range of phase separation is surrounded by a one-phase system. The range of phase separation can be subdivided into a region of flocculation and/or coacervation in contrast to stable symplex dispersions. By increasing the molecular weight of the components the range of phase separation is increased and phenomena of flocculation followed by coacervation were observed predominantly. Above a molecular weight of 10 000 g/mol the transition to concentrated macroscopic homogeneous one-phase systems was observed at a constant ionic strength of 2 mol/l coinciding with the «critical ionic strength» for Coulombic interactions in this system. That means the transition to concentrated one-phase systems can be understood by the disappearance of Coulombic forces above a system-specific ionic strength resulting in a quite additive behaviour of the mixtures with regard to the components.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Carboxymethyl cellulose and C-6-carboxy cellulose were treated with SO3 and HSO3CL in DMF yielding the corresponding watersoluble sulfate half-esters. A preferred sulfation of primary hydroxyl groups was found by 13C-n. m.r. spectroscopy. The potentiometric titration of the polyelectrolytes showed significant differences in the titration behaviour which can be explained by the different acidity of the carboxy groups in the two cellulose derivatives.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyanion-Polykation-Wechselwirkungen zwischen der freien Base Polyethylenimin und dem Natriumsalz der Polyacrylsäure wurden in Abhängigkeit der Polymerkonzentration untersucht. Bei einer Polymerkonzentration zwischen 0,003 und 0,15% beobachteten wir einen eng begrenzten Bereich der Phasentrennung, den wir mit Hilfe einer Methodenkombination bestehend aus Potentiometrie, Konduktometrie und Turbidimetrie auf vorrangig nicht-Coulombsche Wechselwirkungskräfte zurückführen konnten. Bei einer Erhöhung der Polymerkonzentration darüber hinaus beobachteten wir keine derartigen Phasentrennungsphänomene mehr, aber in Abhängigkeit des molaren Verhältnisses von kationischen zu anionischen funktionellen Gruppen sowie der Molmasse der Komponenten eine signifikante Viskositätssteigerung über das Niveau der Einzelkomponenten hinaus. Unsere Ergebnisse aus den NMR-spektroskopischen Untersuchungen und Dichtemessungen werden im Rahmen eines Modells zur Beschreibung der Wechselwirkung in konzentrierten Systemen diskutiert.
    Notes: Polyanion-polycation interactions between the free base poly(ethylene imine) and poly(acrylic acid, sodium salt) were investigated in dependence on polymer concentration of the components. At very low polymer concentration between 0.003% and 0.15% we observed a small range of phase separation, because of predominantly non-Coulombic interactions, determined by using a method combination, consisting of potentiometry, conductometry and turbidimetry. By increasing the polymer concentration no phenomena of phase separation could be observed but a significant viscosity increase above the level of the components in dependence on the molar ratio of cationic to anionic functional groups as well as the molecular weight of the components. The results of NMR spectroscopic investigations in combination with density measurements are discussed with regard to a model of interaction at high concentrations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 333-338 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Comparing a C-6-substituted carboxy cellulose and carboxy methyl cellulose samples differing in substituent distribution, the acidity of the COOH-group and the symplex formation of these polymers are investigated. The acidity of the COOH-group is inversely correlated to the average distance between the anionic charge centre and the anhydroglucose ring. Obviously, no significant effect of the regioselectivity of substitution on symplex formation exists.
    Notes: Es wird über vergleichende Untersuchungen zur Acidität der Carboxygruppe und zur Symplexbildung bei einer C-6-substituierten Carboxycellulose einerseits, Carboxymethylcellulosen mit unterschiedlicher Substituentenverteilung andererseits berichtet. Die Acidität der Carboxygruppe korreliert invers zum mittleren Abstand zwischen anionischem Ladungszentrum und Anhydroglucosering. Ein signifikanter Einfluß der Regioselektivität der Substitution auf die Symplexbildung besteht offensichtlich nicht.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 28-31 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Symplex formation between various eationic polyelectrolytes and solutions of carboxymethyl cellulose differing in microgel content was investigated by means of turbidimetric and conductometric titrations. The gel content influences on the shape of the turbidity curve in the case of poly-DMDAAC as the eationic component, and a correlation between the lenght of the steep initial part of the curve and the level of gel content can be stated. Possible preparative and analytical applications of these observations are discussed.
    Notes: Mittels turbidimetrischer und konduktometrischer Titration wurde die Symplexbildung zwischen verschiedenen kationischen Polyelektrolyten und Carboxymethylcellulose-Lösungen unterschiedlichen Gelpartikelgehaltes untersucht. Der Gelgehalt beeinflußt im Falle von Poly-DMDAAC als kationischer Komponente die Form der Trübungskurve, wobei sich ein Zusammenhang zwischen der Länge des steil verlaufenden Anfangsteils der Kurve und der Höhe des Gelanteils ergibt. Präparative und analytische Anwendungsmöglichkeiten dieser Beobachtungen werden diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyanion-polycation interaction (symplex formation) with two ampholytic copolymers of vinyl(ethinylpiperidole) and acrylie acid, and of the N-methylated analog and methacrylie acid has been investigated by turbidimetry, conductometry, and potentiometry. The results are discussed from the aspect of competition between homosymplex formation by interaction of the acid and basic groups of the polyampholyte and heterosymplex formation between one kind of functional groups of the ampholytic polymer and an oppositely charged polyion. They are compared with previous results obtained with other ampholytic copolymers.
    Notes: Die Polyanion-Polykation-Wechselwirkung (Symplexbildung) Wurde bei zwei ampholytischen Copolymeren aus Vinylethinylpiperidol und Acryläure bzw. des N-methylierten Analogen und Methacrylsäure turbidimetrisch, konduktometrisch und potentiometrisch untersucht. Die Ergebnisse werden unter dem Aspekt einer konkurrierenden Homosymplexbildung zwischen den funktionellen Gruppen des Polyampholyten und Heterosymplexbildung zwischen einer Art der funktionellen Gruppen des Polyampholyten und einem entgegengesetzt geladenen Polyion diskutiert und mit früheren Resultaten bei anderen ampholytischen Copolymeren verglichen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unter Verwendung kationischer covalent vernetzter hoch gequollener Mikrogele auf Polyallylaminbasis und anionischer Latices aus Methacrylsäure-Epoxypropylmethacrylat-Copolymeren wird die Wechselwirkung dieser Polymerkolloide mit entgegengesetzt geladenen Makroionen mittels Potentiometrie, Konduktometrie und Turbidimetrie untersucht. Die Mikrogele verhalten sich bei der Symplexbildung ähnlich wie gelöste lineare Polyelektrolyte, wenn beide Titrationskomponenten in neutralisierter Form vorliegen, während bei einer Umsetzung zwischen freier Polysäure und freier Polybase primär nur die leicht zugänglichen Ladungszentren der Mikrogele and der Umsetzung mitwirken. Bei den Latices bildet sich bei der Titration eine stabile “Symplex-Dispersion”, während im Falle der Mikrogele Flockung erfolgt. Die Ergebnisse werden hinsichtlich des Einflusses der Zugänglichkeit der Polymerkolloide auf Stöchiometrie und Dispersitätszustand der gebildeten Symplexe diskutiert.
    Notes: Employing cationic, covalently crosslinked polyallylamine-based highly swollen microgels and anionic latices obtained by copolymerization of methacrylic acid and epoxypropyl methacrylate, the interaction of these polymer colloids with oppositely charged linear macroions is investigated by potentiometry, conductometry and turbidimetry. The microgels behave similar to linear macroions in symplex formation, if the components are reacted in the neutralized state, while in a “free acid - free base” titration only the easily accessible sites of the microgels are primarily involved in the interaction. With the more compact polymer latices a stable dispersion is formed, while with the microgels flocculation occurs. The results are discussed with regard to the influence of physical structure of the polymer colloids on stoichiometry and state of dispersion of the symplexes formed.
    Additional Material: 5 Ill.
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