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  • 1980-1984  (9)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 17 (1984), S. 2264-2269 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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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
    Notes: In an expectation as potential media for photosensitized electron transfer reactions, polymers carrying both strong electrolytic and hydrophobic segments were prepared by the copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and styrene. The AMPS segments were found to have a remarkable power to solubilize the hydrophobic segments into water, i.e., even a copolymer with a styrene mole fraction of 0,72 is still soluble in water. Salt effect on the reduced viscosity, broadening of NMR spectra in D2O, and enhanced excimer fluorescence of styryl groups in aqueous solution indicated a pronounced hydrophobic interaction of a number of styryl groups along the chain in the copolymer with high styrene content. 8-Anilinonaphthalene-1-sulfonic acid, 1,6-diphenyl-1,3,5-hexatriene, and a cyanine dye were used as fluorescent probes for the hydrophobic microdomains. The results suggested that the microdomains are highly hydrophobic in nature but less capable to solubilize the fluorescent probes than the surfactant micelles. An electron microscopic image of the copolymer was also discussed as a supporting evidence for the presence of microdomains.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 953-960 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For a fundamental study of the electrochemical behavior of electroactive polymers a series of poly(3-vinyl-10-methylphenothiazine) (polyMPT), copolymers of 3-vinyl-10-methylphenothiazine and methyl methacrylate (MMA) (copolyMPT), and 3-ethyl-10-methylphenothiazine (EMPT) (a related monomer model) were prepared. The methylphenothiazine groups in these compounds showed reversible, one-electron oxidation waves in the triangular-were voltammograms. From a detailed comparison of the voltammograms between these polymers and EMPT it was revealed that the electroactive groups in poly MPT were not the “noninteracting” centers in the strict sense, whereas those in copolyMPT, in which the centers are spaced with the MMA segments, were typically noninteracting in nature; that is, in polyMPT the oxidation takes place at the potential 40 m V lower than that of EMPT and copolyMPT exhibited a wave identical to that of EMPT in shape and potential. The exhaustive electron transfer occurred from polyMPT to the electrode. On the other hand, a significant number of centers remained unoxidized in copolyMPT. The self-exchange electron transfer within the polymer coil facilitates the exhaustive oxidation. For this event the proximity of the centers was an essential factor.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 2007-2017 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amphiphilic block copolymers of 9-vinylphenanthrene (VPh) and methacrylic acid (MA) were prepared by a two-step living anionic polymerization of VPh and trimethylsilyl methacrylate followed by hydrolysis of the trimethylsilyl ester groups. Bis(2-hydroxyethyl) terephthalate, an oxidative quenching agent with amphiphilic nature, strongly quenched the fluorescence of phenanthrene groups in the block copolymer in aquecus solution. Apparent second-order rate constants kq for the quenching ranged in the magnitude of 1011-1012M-1 s-1 in the borate (pH 9) and phosphate (pH 7) buffers, whereas those in DMF solution were found to be ∼109M-1 s-1. No such difference in kq for the aqueous and DMF solutions was observed with the related random copolymer. The results suggest that a considerable increase in the effective concentration of the quencher around the VPh sequences in the block copolymer resulted from hydrophobic association. Fumaric acid (FA), an anionic quencher, did not quench the fluorescence of the copolymer at pH 9 and 7, presumably because of the lack of accessibility of the quencher to the copolymer due to electrostatic repulsion. However, in neat water in which only a part of the carboxyl groups of MA sequences are dissociated and therefore the charge effect is minimized, FA quenched the fluorescence, with the kq value approximating the diffusion control limit.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 299-310 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amphiphilic block copolymers consisting of methacrylic acid (MA) sequences and p-N,N-dimethylaminostyrene (DMS) sequences were prepared by living anionic polymerization. DMS was polymerized by lithium naphthalene in tetrahydrofuran to yield a living polymer solution, to which trimethylsilyl methacrylate (TMSM) was added to allow the block copolymerization. The conversion of TMSM was dependent on the countercation, i.e., with Na+ as counterion, no quantitative conversion was reached owing to premature termination, whereas with Li+ the conversion was quantitative. The role of the counterion was discussed in some detail in connection with self-termination by the backbiting mechanism. The trimethylsilyl ester groups in the block copolymer were quantitatively hydrolyzed by treatment with aqueous methanol at room temperature, yielding MA sequences. The block copolymer of MA and DMS exhibited micellar properties in an aqueous solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 2 (1981), S. 507-510 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amphiphilic polymers were prepared by the copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and aromatic vinyl compounds such as 9-vinylphenanthrene (VPh) and 1-vinylpyrene (VPy) with the expectation that they would serve as potential media for photosensitized electron transfer reactions. AMPS strongly solubilizes the hydrophobic segments into water; i.e., poly(AMPS-co-VPh) with VPh mole fraction (fPh) up to about 0.60 and poly(AMPS-co-VPy) with VPy mole fraction (fPy) up to about 0.35 were found to be soluble in water. Poly(AMPS-co-VPh) in aqueous solution, as compared with that in DMF solution, showed a broad fluorescence spectrum with significant tailing in the longer-wavelength region along with a decrease in the intensity of the structured, monomer fluorescence band. These phenomena seem to imply the presence of an excimerlike interaction of phenanthryl groups in an aqueous solution through which the fluorescence from excited VPh units may be partly self-quenched. A considerable enhancement of the fluorescence from sodium 8-anilino-1-naphthalenesulfonate (ANS) caused by hydrophobic interaction of the probe with poly(AMPS-co-VPh) in aqueous solution indicated that these copolymers assume micellar structures. The fluorescence of these copolymers in aqueous solutions was quenched by bis(2-hydroxyethyl)terephthalate (BHET), an amphiphilic quencher, far more effectively than by fumaric acid, a hydrophilic quencher. This tendency is particularly strong for the copolymers with higher content of hydrophobic units. The second-order rate constants for the quenching of poly(AMPS-co-VPh) (fPh = 0.58) by BHET were found to be ca. 3 × 1010 and 1.5 × 109 M-1 s-1 in aqueous and in DMF solution, respectively. The larger value in an aqueous solution is presumably due to an increase of the effective concentration of the amphiphilic quencher around the VPh sequences of the copolymer resulting from hydrophobic interaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 2439-2449 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The exciplex formation in 9-vinylphenanthrene-p-N,N-dimethylaminostyrene copolymers, its characteristics, and the electron transfer process in polar solvents were studied. The copolymer exhibited a more intense intramolecular exciplex fluorescence than the low-molecular-weight model system, phenanthrene-N,N-dimethylaniline, in which the intermolecular exciplex formation occurred. Intensities of the exciplex fluorescence, which were unchanged regardless of the copolymer composition, led us to speculate that the efficient energy migration takes place from an excited phenanthrene unit to an exciplex forming site on the polymer chain. The electron transfer in the copolymer-p-dicyanobenzene system was studied in polar media. The formation of p-dicyanobenzene anion radical was measured by flash photolysis and electron spin resonance (ESR). p-Dicyanobenzene anion radical was generated by the electron transfer process via exciplex and the direct electron transfer process from the excited phenanthrene unit in the copolymer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 21 (1983), S. 167-170 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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