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  • 1
    Publication Date: 2018-01-20
    Description: Crystal Growth & Design DOI: 10.1021/acs.cgd.7b01550
    Print ISSN: 1528-7483
    Electronic ISSN: 1528-7505
    Topics: Chemistry and Pharmacology , Geosciences , Physics
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In Gegenwart einer Lithiumdispersion copolymerisieren Styrol und Methylmethacrylatnach einer radikalisch-anionischen Wachstumsreaktion; dies steht in Einklang mit Meßergebnissen von TOBOLSKY und Mitarb. Messungen der Homopolymerisationsgeschwindigkeit lassen auf einen wesentlich stärkeren Anteil des Styrols am Startschritt schließen, erklärbar durch einen leichteren Elektronenübergang vom Lithium auf dieses Monomere.Ausgehend von verschiedenen Molenbrüchen Styrol in den Monomerengemischen, so 0,48, 0,736 und 0,84, wurden Copolymere mit 4, 11 bzw. 22% Styrolgehalt erhalten. Diese Zusammensetzung wurde durch Fällungsfraktionierung an 4 Proben bestätigt.In Gegenwart von Benzochinon ist es möglich, den relativ starken Anteil am anionischen Wachstum herabzusetzen und so den Styrolgehalt der Copolymeren beträchtlich zu steigern. Für eine gegebene Monomerlösung mit 0,723 Mol Styrol und 0,778 Mol Methylmethacrylat beträgt in Gegenwart von 1, 1,5 und 2,5% Benzochinon, bezogen auf die Monomeren, der Styrolgehalt im Copolymerisat 20, 24 und 30 Gew.-%.Diese Ergebnisse weisen eindeutig auf die Dualität des Wachstumsmechanismus bei dieser durch Lithiummetall initiierten Copolymerisation hin.
    Notes: In the presence of a lithium dispersion, styrene and methyl methacrylate copolymerize by a radical-anionic propagation in agreement with TOBOLSKY's et al. datas, Homopolymerization rate measurements suggest a much more active participation of the styrene in the initiation step by an easy electron transfer from lithium to this monomer.Using various molar fractions of styrene in the monomer mixture, namely 0.48, 0.736, and 0.84, copolymers were obtained containing 4, 11, and 22% styrene, respectively, and these compositions were confirmed by precipitation fractionation of four samples.In the presence of benzoquinone it was possible to reduce the relative importance of the anionic growth, and thus to increase appreciably the styrene content of the copolymers. For a given monomer solution containing 0.723 mole of styrene and 0.778 mole methyl methacrylate, the styrene content of the copolymers was equal to 20, 24, and 30 weight precent in the presence of 1, 1.5, and 2.5% benzoquinone with respect to the monomers, respectively; in the absence of benzoquinone, the styrene content was only 4%.These results demonstrate unequivocally the duality of the propagation mechanism during these lithium metal initiated copolymerization.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 128 (1969), S. 263-271 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aliphatische Bisazide wie 1.5-Bisazido-pentan, 1.4-Bisazido-butan und Bis-(β-azidoäthyl)-äther können mit Hexamethylen-, und m- und p-Phenylenbismaleinsäureimiden kondensieren, wobei Poly-Δ2-1.2.3-triazoline entstehen. Auf gleiche Weise wurden 1.4- und 1.5-Bisazidoalkane mit m- und p-Diäthinylbenzol kondensiert, was die entsprechenden Triazolpolymeren gab. Mit 1.6-Bisdiazohexan geben die Diäthinylbenzole je nach den Reaktionsbedingungen Pyrazolenin- oder Pyrazolpolymere.Die Strukturen dieser neuen Polymeren wurden auf Grund der IR- und NMR-Spektren im Vergleich mit ihren niedermolekularen Modellverbindungen nachgewiesen.
    Notes: Aliphatic bisazides, 1.5-bis-azidopentane, 1.4-bis-azidobutane and bis-(β-azidoethyl)-ether have been condensed with hexamethylene, m- and p-phenylene bismaleimides and give poly-Δ2-1.2.3-triazolines. Similarly 1.4- and 1.5-bisazidoalkanes were condensed with m- and p-diethinylbenzene, and afford the corresponding triazole polymers. With 1.6-bis-diazohexane, the diethinylbenzene give pyrazolenine or pyrazole polymers depending on the reaction conditions.The structures of these new polymers were demonstrated on the basis of their infrared and NMR spectra, and comparison with those of their low molecular weight model substances.
    Additional Material: 6 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 69 (1963), S. 140-153 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Styrol wurde unter Benutzung von 4,4′-Azo-di-4-cyan-valeriansäure als Initiator polymerisiert; die Carboxylendgruppe des Polystyrols wurde mit t-Butylperoxyd verestert. Dieses Polystyrol, das t-Butylcarbonsäureperester als Endgruppe enthielt, wurde als Initiator für die Polymerisation von Methylmethacrylat benutzt, um Blockpolymere von Styrol und Methylmethacrylat zu erhalten. Diese zweite Polymerisation ist praktisch 1. Ordnung in bezug auf das Monomere und 0,5. Ordnung in bezug auf den Initiator. Die relative Reaktivität der beiden Radikale  -  des Makroradikals (—CH2—CH2—COO• oder —CH2—CH2•) und des t-Butyloxy- oder Methylradikals (letzterer entstanden durch Disproportionierung des t-Butyloxyradikals)  -  wurde ermittelt aus der Fähigkeit, das zweite Monomere anzulagern.Messung der Mengen an Blockpolymeren RB und Homopolymeren RH durch fraktionierte Fällung und Bestimmung ihrer Zusammensetzung ermöglichte die Bestimmung des Verhältnisses RH/RB; dieses beträgt 0,15-0,17. Die Startausbeute des Makroradikals beträgt also nur 1/6 von der des t-Butylradikals. Dieses Resultat wird gedeutet durch die Annahme einer Startreaktion in Form einer Kettenübertragung vom Makromolekül auf das Monomere. Bei Durchführung der Polymerisation von Methylmethacrylat in einem Nichtlösungsmittel wird die Startausbeute der Blockpolymerisation noch beträchtlich herabgesetzt (ungefähr um den Faktor 20), und zwar wegen der Unerreichbarkeit der Kettenendgruppen durch die Monomermoleküle.
    Notes: Polystyrene carrying-butylcarboxy-perester end-groups had been synthesized by polymerization of styrene in the presence of 4,4′-azo bis(4-cyanopentanoic acid) as initiator, and esterification of this end-carboxyl polystyrene with-butyl hydroperoxide. This polystyrene carrying-butylperester end-groups was used at 100°C. as initiator of the polymerization of methyl methacrylate for the synthesis of block-polymers of styrene and methyl methacrylate. This second step polymerization is practically a first order reaction with respect to the monomer concentration and 0.5 order with respect to the initiator. The relative reactivity of both radicals, the macroradical (bond;CH2—CH2—COO* or CH2—CH2*) and the t-butyloxide or methyl radical (by dismutation of C4H9O*), has been evaluated from their ability of second monomer addition.By measuring the amounts of blockpolymer RB and of homopolymer RH by fractional precipitation and determination of their composition, it was possible to determine the ratio RB/RH; this ratio is equal to 0.15-0.17; consequently the efficiency of initiation of the macroradical is only one-sixth of that of the t-butyloxide radical. This result is interpreted by assuming an initiation step by chain transfer reaction of the macroradical with the monomer. By carrying the polymerization of methyl methacrylate in a precipitating medium the efficiency of block polymerization is considerably reduced (about 1/20th) on account of the unaccessibility of the chain end-groups to the monomer molecules.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Russian Abstract.
    Abstract: An Hand von Beispielen werden verschiedene Verfahren zur Synthese von neuen Polyadditionspolymeren dargestellt. Im einzelnen werden folgende Verfahren diskutiert: - die 1,3-dipolare Polyaddition- die Dimerisierung von Bisdiazoalkanen und die Polymerisation von Diazoalkanderivaten- photochemische Polycycloaddition
    Notes: Different methods for the synthesis of new polyaddition polymers are considered and illustrated on the basis of original examples.The following methods will be successively discussed: -1,3 dipolar polyadditions-dimerization of bisdiazoalkanes and polymerization of diazoalkane derivatives-photochemical polycycloaddition
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 253-258 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Die Mischpolymerisation von Maleinsaeure Anydrid mit verschiedenen Vinyl-Verbindungen wie Methakrylsaeure, Methylester, Vinylchlorid, Vinylazetat und Isopropenylazetat wurde untersucht. Die Verhaeltnisse der Geschwindigkeits-Konstanten r1 und r2 wurden fuer jeden dieser Faelle festgestellt. Die Mischpolymerisation mit Monomeren, die eine elektronreiche Doppelverbindung enthalten, zeichnet sich durch eine hohe Selektivitaet aus. In diesen Faellen koennen die Ergebnisse nicht gaenzlich durch das Alfrey-Price Schema erklaert werden.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The infrared spectra of synthetic poly-1-phenyl- and poly-2-phenylbutadienes have been examined, principally in the region from 9 to 15 μ. The different intramolecular structures of these polymers, corresponding to the different types of monomer additions (1,4, 1,2, and 3,4) were examined by this method; the data are in complete agreement with the chemical results as reported previously. The influence of the method of polymerization on the internal structures of the polymers is taken in evidence; the presence of the aromatic substituent in position 1 or 2 in the monomer molecule exerts a large influence on the position and the intensity of the characteristic absorption bands, if they are compared with the results for synthetic polyisoprenes.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 14 (1954), S. 126-127 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 34 (1959), S. 287-307 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The two-step synthesis of graft copolymers was carried out by several methods. In the first method, the initial peroxidized polymer was prepared from a copolymer of methyl acrylate and acroyl chloride by recation with tert-butyl hydroperoxide; the content of perester could be varied. The rate of decomposition of these perester groups and the degradation velocity of this first-step polymer were determined in benzene solution at various temperatures. The activation energies were 30.1 kcal./mole, respectively, which values correspond to the scission of the O—O linkage. Grafting experiments were carried out in dilute solutions (1%) in order to avoid any grafting by transfer to the polymer. The second-step polymerization followed the square-root law dependence with respect to the peroxide polymer concentration. This rate was also of the first order with respect to the monomer, i.e., styrene, concentration. The rate of grafting was also evaluated by quantitative fractionation of the reaction products (precipitation method), taking into account the weight per cent of styrene in these isolated graft copolymers. The rate of grafting was also of the first order with respect to the monomer concentration. A comparison of the total rate, Rp, and the rate of grafting, Rg, indicates that, at low perester-content, Rg is about one-half of Rp, while at high perester content, Rg is much lower than Rp as a result of the recombination of redicals. These kinetic result are discussed on the basis of a general reaction scheme. In the second method, first-step polyners carrying tert-butyl peroxide endgroups, were prepared on the basis of the decomposition of tert-butyl hydroperoxide in the presence of cupric octoate. The influence of the concentration of this copper salt on the rate of polymerization has been considered. The first-step polymers so produced can initiate the polymerization of a second monomer, so that block copolymers are obtained by chain extension, probably on both sides. In a third method, the initial peroxidic polymer was obtained by electrolysis of an aqueous solution of polymethacrylic acid. The experimental conditions are discussed. The hydroperoxide-containing polymers, prepared and isolated at below 10°C., can be used for a second-step polymerization with another monomer, e.g., acrylamide. Graft copolymers were thus obtained; these hydroperoxidic polymers are, however, relatively unstable, particularly because of the presence of neighboring acid groups.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 40 (1959), S. 203-216 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several copolymers of methacrylic acid and methyl methacrylate have been prepared with acid contents of 28.8, 50, 60, 66, 72, 83, and 86.5%; they have been hydrolyzed in acidic medium at 110°C. at different neutralization ratios r = [HA]/[A-]. Except for those with the highest acid content, all the copolymers show a two-step hydrolysis, in which the second step is about 1/6-1/7 slower than the first. The order of reaction is one with respect to the acid concentration and one with respect to the ester concentration. On the basis of general catalysis, as suggested by Brønsted, two hydrolysis rate constants kHA and kA- may be evaluated; they correspond to the hydrolysis catalyzed by undissociated carboxyl groups and by carboxylate groups. At 110°C., kHA and kA- are equal, respectively, to 1.5 × 105 and 1.0 × 105; consequently, the rates of hydrolysis are practically insensitive to the ratios of neutralization r, except when r = 3. From comparison of the behavior of these acid-ester copolymers with that of a methyl methacrylic-N-vinylpyrrolidone copolymer in the presence of an acid-buffered solution (acetic tic or polymethacrylic acid), it becomes evident that the hydrolysis reaction consists essentially of a functional interaction between an ester function on one side, and a carboxyl and/or a carboxylate directly neighboring function on the other side. Moreover, on the basis of structural probability calculations, the immediate vicinality effect is insufficient to explain the rates and limited degree of conversion of the hydrolysis reaction. For the copolymers with high acid content (C72, C83, and C86.6) at r = 3, the rate of reaction is triple that at the other r-values. This strong increase of the reaction velocity is, as expected, characterized by an appreciable decrease in the energy of activation (16 kcal. instead of 23 kcal.) This behavior is attributed to a “concerted” mechanism which should be particularly enhanced at r = 3. It has been demonstrated that the stereochemical composition of these copolymers exerts a deep influence on the rate of hydrolysis as well as on the degree of conversion in these reactions.
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