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  • Polymer and Materials Science  (10)
  • Polymers  (1)
  • 1985-1989  (11)
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  • 1
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Spin-lattice relaxation rates (1/T1) have been used to study the correlation between the molecular motions in the polyion components of polyelectrolyte complexes from poly(dimethyliminioalkylenes) (α,ω-ionenes) and polystyrenesulfonate. The length of the alkyl chains in the α,ω-ionenes has been varied studying the complexes with 3,3-ionene, 6,6-ionene, and 10,10-ionene, respectively. In the latter, three different positions in the alkylene chains were deuterated selectively. The relaxation rate curves show that the more rigid polystyrenesulfonate component of the complexes is relaxed through the rapid large-angle motions in the alkylene chains of the α,ω-ionenes. In the complex with 10,10-ionene coupling is stronger with the mobility of the CH2 groups adjacent to the quaternary ammonium ion.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 2367-2379 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 2H NMR is used to study the mobility of the alkylene chain in solid poly[(dimethyliminio)-alkylene]s (α,ω-ionenes) complexed with poly(styrenesulfonate). In 10, 10-ionene the alkylene chain motion was probed on samples selectively deuterated at the 1-, 2-, and 4-position as well as in the methyl part of the quaternary ammonium groups. 2H NMR spectra show that all positions in the polymethylene chains are involved in conformational jumps between trans and gauche states. The mobility of the methylene units adjacent to charged centres was found to be significantly reduced compared with that of units in the inner part of the chain. The charged quaternary ammonium groups themselves, however, do not take part in trans-gauche isomerization. An increase in mobility resulting from increasing the length of the alkylene chains between the charge centres was observed in 3,3-, 6,6- and 10,10-ionene complexes labelled in the 2-position. The differences in chain dynamics were also detected via EPR line shapes of small spin probe molecules incorporated into the complexes.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 2711-2723 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The molecular order and mobility of two liquid-crystalline polyacrylates with phenyl benzoate moieties as mesogenic side groups and (CH2)m spacers (m = 2 and m = 6) were investigated by pulsed 2H NMR. The mesogenic side groups were isotopically labelled at the terminal phenylene ring. In the glassy state the orientational distribution function was characterized from the angular dependence of the 2H NMR line shape of samples macroscopically ordered in their nematic phase by the 8,4 T magnetic field of an NMR spectrometer. It was found to be Gaussian with widths of ± 18,5° and ± 10,5° for the m = 2 frozen nematic and m = 6 frozen smectic system, respectively. The phenylene rings undergo 180° jumps about their local C2-axes in the glassy state. The time-scale of this process, however, was found not to be uniform. Instead, the analysis of 2H NMR line shapes and their intensities as a function of temperature yielded a log-Gaussian distribution with correlation times characteristic of amorphous solids, 2,2 versus 2,5 decades in width and mean activation energy ĒA = 42 versus 47 kJ/mol for the m = 2 and m = 6 system, respectively. The correlation times for the centre of the distribution agree with those obtained by dielectric relaxation measurements of the same systems, suggesting that reorientation of the whole mesogenic group is detected via the phenylene rings.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The 13C solid-state NMR spectra of the aromatic polyester 1 with flexible hexadecyloxy side chains are measured at temperatures below and above its solid-solid phase transition in order to study the conformation of the side chains. The signals due to the CH2 carbons reflect the ratio of trans and gauche conformations at the various positions along the chain. An increase in the gauche content was observed towards the end of the side chain in both phases, however, in the low temperature phase the spectra are dominated by all-trans sequences. The solid-solid transition, as detected by differential scanning calorimetry corresponds to a large increase in the gauche content at all positions on the side chain, except near to the rigid polymer backbone. Above the solid-solid transition a small residual concentration of all-trans sequences was detectable.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2935-2949 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Pulsed 2H NMR was used to study the molecular mobility of a polymer model membrane. The polymerizable lipid analogue consists of a quaternary ammonium ion with two C18 alkyl chains and a methacryloyl moiety attached to the hydrophilic head group via an alkyl spacer. The bilayer spacing as obtained from small angle X-ray scattering was found to be 3 nm in the lamellar Lβ gel phase of the monomer and 3,5 nm in the polymer indicating an interdigitated structure. The molecular mobility in both the monomer and the polymer below and above the phase transition Lβ → Lα was investigated by the NMR lineshapes and the transverse relaxation time T2 at five positions of the monomeric unit: a methylene group of the spacer, the head group and three methylene groups of the alkyl chains (1-, 2-, and 7-position). In contrast to the monomer a pronounced motional gradient was observed in the polymer, where the spacer is almost completely immobilized, whereas the mobility in the middle of the hydrophobic chains is largely retained. A quantitative analysis of the NMR lineshapes shows a gradual increase of molecular mobility in the polymer above the phase transition due to an increase in both the jump rate and the number of conformational transitions.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The function of lipid bilayer membranes crucially depends on their mobility and their ability to incorporate components that, e.g., can change molecular order and dynamics or form channels. Since polymerization increases the stability of model membranes at the expense of their mobility a compromise must be sought. Therefore, the effect of different polymerization schemes on the structure and dynamics of polymer membranes has to be checked. To this end X-ray scattering, DSC-thermal analysis and a variety of spectroscopic techniques probing the dynamics on largely different time--- and length scales were employed, i.e. 2H-NMR, ESR, fluorescense anisotropy and FRAP. These studies showed that in model membranes polymerized in the hydrophylic region the head group mobility can be controlled by the length and the nature of the spacer connecting it to the polymer backbone. The head group region is much less affected, if the polymerization is achieved in the hydrophobic region. By use of a lipid analogue carrying a polymerizable group on only one of its two alkyl chains, membranes retaining high mobility in the hydrophobic region can be generated. Typical membrane constituents, i.e. cholesterol, gramicidin and ubiquinone can be incorporated and the mixtures show a behaviour similar to natural model membranes, although lateral diffusion of the lipids is frozen as a consequence of the polymerization.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0570-0833
    Schlagwort(e): NMR spectroscopy ; NMR spectroscopy ; Polymers ; Analytical methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: NMR spectroscopy is an effective method not only for examining liquid samples but also for characterizing molecular sturcture, order and dynamics in amorphous and ordered solids. Recent developments in the area of solid-state NMR spectroscopy span from model-dependent studies of conventional one-dimensional spectra to the more definitive two-dimensional (2D) spectra which provide more specific information. For example, with 2D-NMR spectroscopy it is possible to determine the orientational distribution functions of molecular segments in drawn polymers and to distinguish different mechanisms of complex molecular motions. Following an introduction to basic NMR spectroscopy, an overview of the current state-of-the-art of 2D methods in solid-state NMR spectroscopy is presented and demonstrated with selected examples.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 7 (1986), S. 449-453 
    ISSN: 0173-2803
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 7 (1986), S. 777-783 
    ISSN: 0173-2803
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 9 (1988), S. 337-343 
    ISSN: 0173-2803
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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