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  • Polymer and Materials Science  (11)
  • Physics  (1)
  • Polymers
  • 1995-1999  (11)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Columnar mesophases of alkylated hexa-peri-hexabenzocoronenes with remarkably large phase widthsFinancial support from the Bundesministerium für Bildung und Forschung is gratefully acknowledged. We also thank Sigrid C. Kuebler for her help in recording the 2H-NMR spectra. (1996)
    Weinheim : Wiley-Blackwell
    Advanced Materials 8 (1996), S. 510-513 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19960080613
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  • 2
    Electronic Resource
    Electronic Resource
    Visualization of immobilization in shear bands by NMR imagingThe authors thank Dr. A. Karbach, Bayer AG, for providing the PC, Dr. T. Pakula and J. Vennemann for the drawing of the sample, and Dr. S. Hafner for helpful discussions. F. W. acknowledges a stipend of the “Studienstiftung des deutschen Volkes”. (1996)
    Weinheim : Wiley-Blackwell
    Advanced Materials 8 (1996), S. 481-484 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19960080604
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  • 3
    Electronic Resource
    Electronic Resource
    Saccharide modified silica particles by enzymatic grafting (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 18 (1997), S. 927-938 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface of silica particles has been chemically modified with oligo- or poly-(α,1←4)-D-glucopyranose (amylose) chains of various length by covalently attaching maltoheptaose derivatives to the solid support and enzymatic polymerization of glucose-1-phosphate with potato phosphorylase (E.C. 2.4.1.1) as catalyst. The characterization of the products by solid-state NMR spectroscopy showed an interesting dependence of the linewidth with the grafting density of the glucan chains. The modified silica particles showed chiral discrimination in liquid chromatography.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1997.030181006
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  • 4
    Electronic Resource
    Electronic Resource
    Microphase separation in RIM polyureas as studied by solid-state NMR (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 693-703 
    Details
    ISSN: 0887-6266
    Keywords: phase separation ; NMR spectroscopy ; block copolymers ; reaction injection molding ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microphase separation (MPS) in polyureas based on methylene diphenyl diisocyanate (MDI) hard segment, diethyltoluenediamine chain extender, and amino-terminated polypropylene glycol soft segment prepared by reaction injection molding (RIM) was studied by advanced solid-state NMR spectroscopy. Incomplete microphase separation leads to the presence of mobilized hard segments dispersed in the soft segment domains as well as immobilized soft segments residing in the hard domains. This is detected by 1H-NMR spectra recorded under spinning at the magic angle (MAS) as well as two-dimensional wide-line separation (WISE) NMR spectra. The sizes of the various domains as well as the interfaces between them are quantified by spin diffusion measurements. In this way the impact of annealing, method of polymerization, and hard segment content on MPS is studied. Whereas annealing at temperatures up to 170°C results in improving the MPS, major changes are observed after annealing at higher temperatures (190°C), where the system changes from “soft-in-hard” to “hard-in-soft” behavior. The MPS decreases with increasing hard segment content. The highest MPS is observed for solution polymerized samples. The various NMR experiments clearly reveal the nonequilibrium nature of RIM systems. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 693-703, 1998
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Optimum measurement temperature for elucidating incomplete phase separation in core-shell latexes by solid state NMR (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 875-883 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Core-shell latexes with a core of poly(buty1 acrylate) (PBuA) and a shell of poly(methyl methacrylate) were studied by solid-state nuclear magnetic resonance (NMR) methods at different temperatures. 13C cross polarization/magic angle spinning spectra show differences in mobility in the mobile PBuA phase. In spin-diffusion experiments the sensitivity of the NMR parameters towards the interphase structure and towards the entire core-shell structure changes with varying temperature. For an efficient characterization of interphase structures in core-shell systems the measuring temperature has to be optimized, i.e. the mobility gradient between the two phases within the particle must be sufficiently high to allow for effective selection by the dipolar filter. Yet, the spin diffusion coefficient of the mobile component should be high enough to allow quantitative evaluation of length scales. It is shown that a measuring temperature of about 60-70 K above the glass transition temperature of the mobile component represents an optimum for fulfilling the different requirements simultaneously.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030171206
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular dynamics in polystyrene from electron spin resonance (ESR) measurements: comparison between spinprobes and -labels attached to the chain ends (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 1121-1134 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The commercially available 15N-TemponeN-Tempone: 4-oxo-2,2,6,6-tetramethylpiperidine-15N-oxyl; Tempol: 4-hydroxy-2,2,6,6-tetramethylpiperidine -15N-oxyl. nitroxide radical has been used for the endfunctionalization of anionically polymerized polystyrene. The temperature dependence of molecular motions of the nitroxide radicals in this chain end labeled polystyrene (PS) and a PS/Tempol mixture has been studied using cw-ESR. Furthermore, these two samples were compared with a mixture of PS with a biradical which has a large molecular volume and is used in its unoxidized form as a polymer additive in commercial products. The temperature dependent spectra were evaluated to give T50G. This allows the volume for reorientation of the radicals and that of a polymer unit to be compared. The temperature dependent spectra were simulated in order to yield the rotational correlation time τR. In contrast to the Tempol probe radical which is highly mobile even at temperatures well below the glass transition temperature (Tg) the spin-label strongly couples to the α-process of polystyrene. The biradical exhibits an intermediate mobility and seems to be weakly coupled to the glass transition dynamics. Line shape analysis shows that the motional behavior of the PS/Tempol mixture can adequately be described by the model of isotropic rotational diffusion, whereas for the chain end label significant deviations from this model are observed indicating anisotropic motion due to restrictions imposed by the polymer chain.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970329
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  • 7
    Electronic Resource
    Electronic Resource
    Structure and dynamics of polyelectrolyte-surfactant complexes as revealed by solid state NMR (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 2713-2727 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C-CP/MAS-NMR (cross-polarization magic angle spinning), 2D-WISE (wideline separation experiment) and 1H-spin diffusion experiments allow to gain new insight into the structure and dynamics of solid polyelectrolyte-surfactant complexes, a material with pronounced mesophase formation. Experiments were performed on two different complexes of polystyrene sulfonate and octadecyltrimethylammonium or tetradecyltrimethylammonium counterions, PSS-C18 and PSS-C14. The strong mobility differences between the ionic and alkyl phase in the lamellar complex PSS-C18 are reflected in the NMR behavior: in the surfactant tails, a mobility gradient towards the terminal methyl group is observed. This fact as well as a high content of gauche conformations suggest a non-interdigitating morphology of the tails at room temperature. The behavior changes during cooling below an endothermic transition centered at 255 K where a high trans content and a homogenization of the side chain dynamics is observed. We attribute this transition which is invisible in the X-ray experiments to the formation of a highly transoid, interdigitated phase of the surfactant tails which is however not crystallized in a classical sense. 1H-spin diffusion experiments allow to estimate the distance between mobile and immobile regions of the sample. For the complex PSS-C14, the length scale determined by NMR is essentially that of the primary lamellar structure. For PSS-C18, a characteristic length of the density fluctuations within the proposed undulated lamellar structure is estimated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970910
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  • 8
    Electronic Resource
    Electronic Resource
    Microheterogeneities of core-shell latexes probed by 1H spin diffusion and transmission electron microscopyDedicated to Prof. Joachim Klein on the occasion of his 60th birthday (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 985-993 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A core-shell latex built up of polybutadiene as a mobile component and polystyrene as a rigid component is investigated. Solid-state NMR spectroscopy and transmission electron microscopy are used to characterize the morphology and possible heterogeneities of the latex particles (average particles sizes 70-100 nm). NMR spectroscopy allows the determination of average domain distances much below the particle size due to standard electron microscopy. These differences are explained by an additional microstructure of the core-shell particles. Indeed, electron micrographs at high resolution confirm the existence of heterogeneities within the polybutadiene core of the latex. The presented investigations demonstrate the power of a combined application of solid-state NMR spectroscopy and transmission electron microscopy for the characterization of core-shell latexes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021960401
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  • 9
    Electronic Resource
    Electronic Resource
    Phase transition from a C-centered to a B-centered orthorhombic crystalline form of syndiotactic poly(propylene) (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 4011-4024 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Samples of highly syndiotactic poly(propylene) (s-PP) crystallized in a C-pseudo-centered orthorhombic form are here characterized through high resolution solid state 13C NMR sepctroscopy and wide angle X-ray diffraction. The 13C NMR CP MAS (cross-polarization, magic angle spinning) spectra of highly disordered quench-precipitated s-PP samples (with a structure very close to a C-pseudo-centered orthrohombic form) yield additional resonances beside those already reported in the literature for s-PP samples crystallized with the chains in a fully helical \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} (TTGG\rlap{--} )_n $\end{document} conformation (T: trans; G: gauche). From the correlation of 13C NMR CP MAS spectra with the X-ray diffraction profiles recorded at the same temperatures, it is possible to establish that at a given temperature (approximately 100°C, for our samples) a phase transition from the C- to the B-pseudo-centered orthorhombic form starts to occur. Correspondingly, the aforementioned additional resonances in the 13C NMR CP MAS spectra progressively disappear with the onset of the phase transition. These extra resonances are indeed completely absent in the 13C NMR CP MAS spectrum of samles crystallized in the B-pseudo-centered structure. NMR and X-ray diffraction data, according to differential scanning calorimetry, were interpreted with a recrystallization phenomenon; at temperatures below 140°C for our samples, the variously sized C-pseudo-centered orthorhombic crystallites melt and readily re-crystallize in the B-pseudocentered orthorhombic form.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021961212
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  • 10
    Electronic Resource
    Electronic Resource
    Solid-state NMR studies of structure and dynamics of erucamide/isotactic poly(propylene) blends (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 985-995 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solid-state NMR spin diffusion experiments and two-dimensional (2D) 1H-13C NMR experiments have been used to study the phase structure, mobility and domain sizes of blends of isotactic poly(propylene) (i-PP) and erucamide (ERU), a low molecular weight slip and antiblock additive for i-PP films. The study of the proton line shapes in pure erucamide and i-PP together with their blends reveals the mobility of the two components. The mobility is higher in the blends than in erucamide and i-PP when they are considered separately. In addition, 2D wideline separation (WISE) NMR spectroscopy indicates that erucamide molecules show both low and high mobilities depending on the erucamide content in the blend. By measuring the proton spin diffusion with 1H detection, the microdomain dimensions have been estimated quantitatively. The domain sizes range from approximately 13 nm to 60 nm.
    Additional Material: 13 Ill.
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