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  • Polymer and Materials Science  (7)
  • 1980-1984  (7)
  • 1920-1924
  • 1983  (7)
Collection
Publisher
Years
  • 1980-1984  (7)
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 579-588 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Binding of the cationic dye auramine O (AuO) to the polysoap-type polymers poly(vinylbenzo-18-crown-6) (P18C6) and polyvinylbenzoglyme (PVBG) in water were studied by fluorimetry and dialysis. The quantum yield of P18C6-bound AuO was found to be 0.028, the value being 0.018 for AuO bound to PVBG. The intrinsic binding constants were found to be 2.2 × 104M-1 (P18C6) and 1.2 × 104M-1 (PVBG), the respective first binding constants being 317 and 63M-1. Addition of crown-ether-complexable cations such as K+, Tl+, or Cs+ converts the neutral poly(crown ether) into a polycation, causing repulsion of the cationic dye and a strong decrease in the AuO fluorescence. AuO fluorescence was also studied in the absence of polymer in ether solvents, giving θ values of 0.011 and 0.018 in THF and dioxane. Traces of water rapidly form a nonfluorescent species. Solutions of AuO in water without polymer present exhibit very strong fluorescence on addition of BPh4 anions owing to formation of AuO+, BPh4- ion pairs and higher aggregates.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 1535-1542 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalytic hydrolysis of enantiomeric substrates by N-decanoyl-L-histidine was studied at pH 7.30, 0.02M phosphate buffer, and 25°C in the presence of quaternized polymers. The rate of reaction is remarkably accelerated in the presence of polyethylenimine derivatives, but the observed stereoselectivity depends on the structure of the substrates.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 2777-2785 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymers that contain crown ether moieties at the side chain and are capable of forming rather tough film were synthesized by the polymer reaction of poly(vinyl alcohol) with formyl derivatives of aliphatic crown ethers such as 12-crown-4, 15-crown-5, and 18-crown-6. In the passive transport of alkali metal picrates across the poly(crown ether) membranes the permeation, particularly of alkali metals which tend to form intramolecular sandwich-type complexes with the crown ether rings, was retarded, compared with a poly(vinyl alcohol) membrane. The cation selectivities in the permeation of poly(crown ether) membranes differed significantly from those of poly(vinyl alcohol).
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 1053-1063 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical copolymerizations of N-alkylitaconimide (RII, R = CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, CH2CH2Cl, CH2C6H5) (M1) with styrene (ST) (M2) or methyl methacrylate (MMA)-(M2) were carried out at 60°C, using azobisisobutyronitrile as an initiator in tetrahydrofuran in order to clarify the substituent effect on the copolymerizations. The monomer reactivity ratios r1, r2 and the Q1 and e1 values were determined from the results obtained. It was found that the relative reactivities 1/r2 of RII toward an attack by a poloystyryl radical could be correlated not by the steric-substituent constant Es of the alkyl group in RII but by the polar-substituent constant σ* in Taft's equation: log(1/r2) = ρ*σ* + δ Es. According to the above equation, the ρ* and δ values were obtained as 0.55 and 0, respectively, in the RII-ST system, while in the RII-MMA system, the ρ* and δ values were obtained as 0.49 and 0, respectively. It was also observed that the Q1values for RII were proportional to σ* constants and that the e1 values for RII were independent of σ* substituent constant. It was also found that the weight-average molecular weights of the copolymers are between 8.5 × 104 and 32.5 × 104.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2191-2206 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octapeptides, cyclo(X-Pro)4, where X represents Phe, Leu, or Lys(Z), were synthesized and their conformations investigated. A C2-symmetric conformer containing two cis peptide bonds was found in all of these cyclic octapeptides. The numbers of available conformations due to the cis-trans isomerization of Pro peptide bonds depended on the nature of the solvent and X residue: they decreased in the following order: cyclo[Lys(Z)-Pro]4 〉 cyclo(Leu-Pro)4 〉 cyclo(Phe-Pro)4 in CDCl3. 13C spin-lattice relaxation times (T1) of these cyclic octapeptides were measured, and the contribution of segmental mobility to T1 was found to vary with the nature of the X residue.
    Additional Material: 12 Ill.
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  • 6
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complex formation with alkali and alkaline earth metal ions of cyclic octapeptides, cyclo(Phe-Pro)4, cyclo(Leu-Pro)4, and cyclo[Lys(Z)-Pro]4 was investigated in relation to conformation. In an alcohol solution, cyclo(Phe-Pro)4 did not form complexes. However, cyclo(Leu-Pro)4 and cyclo[Lys(Z)-Pro]4 formed complexes selectively with Ba2+ and Ca2+ ions. Changing the solvent from alcohol to acetonitrile, the complexation behavior was very different. In acetonitrile, cyclo(Phe-Pro)4 was found to form a complex with Ba2+, and CD spectra of cyclo(Leu-Pro)4 and cyclo[Lys(Z)-Pro]4 changed sharply on complexation with K+. Rate constants of the complex formation between the cyclic octapeptides and metal salts were in the range of 0.7-12 L mol-1 min-1 in an alcohol solution. One of the two types of complex formation in acetonitrile was much faster than that in an alcohol solution.
    Additional Material: 10 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 367-378 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(butylene terephthalate) (PBT) and a copolyester of bisphenol-A with 50% terephthalate-50% isophthalate (PAr), before and after transesterification, have been studied by thermal and dynamic mechanical tests to determine crystallinity and phase behavior. Blends without transesterification, as prepared by solution precipitation, show a single Tg, indicating amorphous miscibility of PBT and PAr. A melting-point depression for PBT crystals is not observed; this means that PBT crystallizes excluding PAr and the entropy of melting is small. The highest fractional crystallinity for PBT is obtained at 20-35% of PAr. Transesterified blends were obtained by holding the physical blends at 250°C for up to 16 h. The transesterified systems show higher Tg's than the corresponding physical blends and also show a marked melting-point depression and lesser PBT crystallinity at the corresponding increased PAr content.
    Additional Material: 10 Ill.
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