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  • 1
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 2139-2140 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 7064-7069 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 4 (1981), S. 711-715 
    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 Two polymerizable derivatives of 4-aminoazobenzene, viz., 4-methacryloylaminoazobenzene (MA-AAB) and 4-(12-methacryloylaminododecanoyl) aminoazobenzene (MA-12-AAB) were prepared and copolymerized with methacrylic acid (MA) and N-(2-hydroxypropyl) methacrylamide (HPMA). The cis-trans thermal isomerization of these copolymers was investigated as a function of temperature, side chain length and character of the polymer carrier.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A method is described for identifying hydrocarbons by means of so-called Chromatographic spectra. In contrast to the older method, in which the compound to be identified is divided into four different parallel connected columns with differing stationary phases and then reunited in a detector after their passage, the procedure in this new variant is pass the organic compound through a column first and then through two parallel columns. A chromatogram is obtained from which it is easy to read the hydrocarbon type to which a component belongs, or the chromatogram can be compared with a standard substance and the identity thus established.
    Abstract: Résumé On décrit une méthode pour l'identification des carbures d'hydrogène à l'aide de ce que l'on appelle les spectres chromatographiques. Contrairement aux anciennes méthodes, dans lesquelles le composé à identifier se trouvait partagé dans 4 colonnes différentes montées en parallèle avec des phases stationnaires différentes puis il était de nouveau réuni après son passage dans un détecteur, ici, dans cette nouvelle variante, on opère de manière à ce que le composé organique passe d'abord à travers une colonne et ensuite à travers deux colonnes disposées en parallèle. On obtient un chromatogramme d'où l'on peut déduire très facilement à quel type de carbure d'hydrogène appartient un composant, et l'on peut comparer le chromatogramme avec celui d'une substance étalon et par suite, faire l'identification.
    Notes: Zusammenfassung Eine Methode zur Identifizierung der Kohlenwasserstoffe an Hand sogenannter chromatographischer Spektren wird beschrieben. Im Gegensatz zu der älteren Methode, wobei sich die zu identifizierende Verbindung in vier verschiedene, parallel geschaltete Kolonnen mit unterschiedlichen stationären Phasen verteilt und nach ihrem Durchgang wieder in einem Detektor vereinigt wird, wird bei dieser neuen Variante so vorgegangen, daß die organische Verbindung zuerst durch eine Kolonne und nachher durch zwei parallel angeordnete Kolonnen läuft. Man erhält ein Chromatogramm, an dem man sehr leicht ablesen kann, zu welchem Kohlenwasserstofftyp eine Komponente gehört, bzw. man kann das Chromatogramm mit dem einer Standardsubstanz vergleichen und so die Identität feststellen.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Einige Stilbenderivate wurden chromatographisch mit fünf verschiedenen Lösungsmittelsystemen identifiziert, elektrophoretisch in zwei verschiedenen Elektrolyten und gaschromatographisch unter Nachweis der Spaltprodukte.
    Abstract: Résumé On a identifié quelques dérivés du stilbène par Chromatographie sur papier dans 5 systèmes différents de solvants, par électrophorèse (sur papier) dans deux électrolytes différents et par Chromatographie en phase gazeuse pour déceler les produits de coupure.
    Notes: Summary Some stilbene derivatives have been identified by using paper chromatography in five different solvents systems, paper electrophoresis in two different electrolytes, and gas chromatography to detect cleavage products.
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  • 7
    ISSN: 1573-4994
    Keywords: Syndiotactic and isotactic poly(methyl methacrylate)s ; stereocomplex formation ; anthracene-labeled polymers ; rotational correlation time ; limiting fluorescence anisotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Poly(methyl methacrylate)s labeled with the anthracene fluorophore were prepared by free radical, anionic, and coordination polymerization yielding atactic and syndiotactic polymers. Unlabeled isotactic poly(methyl methacrylate) was prepared by anionic polymerization. Time-resolved fluorescence spectroscopy was used to study polymer association in solution. The time-dependent decays of fluorescence anisotropy show that stereocomplexation causes an increase in rotational correlation times of anthracene fluorophores both embedded in the polymer backbone and attached at the end of the side chain of polymer molecules. The rotational correlation time of anthracene fluorophore in dimethylformamide as a part of stereocomplex is 11.9 and 30 ns in the side chain and embedded in the polymer backbone, respectively, and shorter than 3 ns in noncomplexing solvent.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4994
    Keywords: Poly[N-(2-hydroxypropyl)methacrylamide] ; Foerster's energy transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By copolymerization of monomers containing donor (carbazole) and acceptor (dansyl) fluorophores withN-(2-hydroxypropyl)methacrylamide (HPMA), statistical copolymers with “low” and “high” contents of the fluorophores were prepared. The increase in nonradiative energy transfer between copolymers with a low content of fluorophores was probably due to intermolecular penetration of the polymer coils in concentrated solutions.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 2 (1980), S. 785-789 
    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 Two soluble photochromic polymers containing 1′-(ß-hydroxyethyl)-3′,3′-dimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline] bound on a variously long side chain were prepared. It was found that the discolouration process depends on the length of the side chain to which the photochromic centre is bound.
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  • 10
    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: Es wurde die Geschwindigkeit der trans→cis Photoisomerisierung des Stilbenrestes im Copolymeren 3 aus 2-Hydroxyäthylmethacrylat (1) und trans-N-4-(4-nitrostyryl)phenylmethacrylamid (2a) einerseits mit derjenigen in dem niedermolekularen Analogon des letzteren, trans-N-4-(4-nitrostyrl)phenylisobutyramid (2b) andererseits, in Methanol, 2-Äthoxyäthanol und in den binären Lösungsmitteln Propanol/Wasser und tert-Butylalkohol/Wasser verglichen. Dabei wurde beobachtet, daß die trans→cis Photoisomerisierung des Stilbenrestes in den Seitenketten des Copolymeren bei 20°C in den meisten Lösungsmitteln schneller als beim 2b verläuft. Dieses Ergebnis kann auf der Grundlage der Abhängigkeit der Quantenausbeute der trans→cis Isomerisierung von der Polarität des Milieus, in dem die Isomerisierung verläuft, interpretiert werden. Die Beschleunigung der trans→cis Photoisomerisierung der Stilbenreste in den Seitenketten des Copolymeren wird durch ein Absinken der Polarität des Mikromilieus des Polymeren im Vergleich zur Polarität des Lösungsmittels selbst verursacht. Diese Interpretation stützt sich auf die direkte Messung der Polarität des Mikromilieus der Polymerkette auf der Grundlage der Kosowerschen semi-empirischen Polaritätsskala. Der Verlauf der trans→cis Isomerisierung von 2b und 3 gehorcht nicht der Gleichgewichtsreaktion erster Ordnung für alle erwähnten Lösungsmittel. Der Einfluß der Vorzugssorption einer der Lösungsmittel-komponenten in binären Lösungsmitteln auf das Polymerknäuel und der Einflulß der Temperatur auf die photochemische trans→cis Isomerisierung werden im Zusammenhang mit den experimentellen Ergebnissen diskutiert.
    Notes: The rate of the trans→cis photoismerization of the stilbene residue was compared in the copolymer 3 from 2-hydroxyethyl methacrylate (1) and trans-N-4-(4-nitrostyryl)phenylmethacrylamide (2a) with its low molecular weight analogue trans-N-4-(4-nitrostyryl)phenylisobutyramide (2b) in methanol, 2-ethoxyethanol and in the binary solvents propanol/water and tert-butyl alcohol/water. It was observed that the trans→cis photoisomerization of the stilbene residues was more rapid at 20°C in the side chains of the copolymer than for 2b in most solvents. This result may be interpreted on the basis of the quantum yield dependence for the trans→cis isomerization on the polarity of the medium where the isomerization takes place. Acceleration of the trans→cis isomerization of the stilbene residues in the side chains of the copolymer results from a decrease in the polymer microenvironment polarity as compared to the polarity of the solvent itself. This interpretation is supported by direct measurement of the polarity of the polymer chain microenvironment, based on the Kosower semi-empirical polarity scale. The course of the trans→cis isomerization of 2b and 3 does not obey the equilibrium, first-order reaction for all the solvents mentioned. The effect of preferential sorption of one of the components in binary solvents on the polymer coil and the effect of temperature on the photochemical trans→cis isomerization are discussed in connection with the experimental results.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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