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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 10701-10706 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The relaxation spectrum at long times has been calculated for comblike micronetworks of Gaussian chains with definite length L, number of subchains N, and generation order g. The calculation is based on the well-known phantom network approximation; thus excluded volume and entanglements effects are not considered. The longest relaxation time is in the present model of the order Ng and diverges for networks of infinite size. This model gives a reasonable phantom description of a rubberlike network with a large number of dangling ends. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 4190-4197 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    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
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 8444-8446 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 40 (1998), S. 211-217 
    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: Abstract. The diblock copolymer of methyl methacrylate and 1H,1H,2H,2H-perfluorooctyl methacrylate was shown to form micelles which could be deposited and imaged on a flat substrate upon casting from a solvent which is selective for the PMMA block, e.g. toluene and THF. The micelle formation was significantly affected by a small content of PMMA homopolymer. While the pure blockcopolymer formed cylindrical micelles, the presence of the PMMA shifted the associated equilibrium to the side of spherical aggregates.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 31 (1997), S. 37-41 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die rote Farbe des kolloidalen Goldes war schon den Alchimisten des Mittelalters bekannt. 1663 beschreibt der Leidener Arzt Andreas Cassius die Färbung von Glas und Porzellan mit Hilfe von Goldverbindungen. Aber auch in jüngster Zeit sind Darstellung und Eigenschaften ultrakleiner Goldteilchen noch ein hochaktuelles Thema. Ein Beispiel sind die von G. Schmid beschriebenen ligandenstabilisierten Goldcluster [1]. Abhängig von der Struktur der Liganden (Thiole, Phosphane, etc.) gelingt es, vor allem kuboktaedrische „Full-shell-Cluster“ aus 13, 55, 147, 309, 561 Goldatomen (die sogenannten magischen Zahlen) in hoher Reinheit zu isolieren.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 911-925 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Melting, crystallization, and solution behavior of n-alkanes with fluorocarbon segments of twelve carbon atoms on one end, F(CF2)12(CH2)nH, or on both ends, F(CF2)12(CH2)n(CF2)12F were investigated by DSC, MAS 13C NMR, light scattering, and birefringence studies. Both triblock F(CF2)m(CH2)n(CF2)mF and diblock F(CF2)12(CH2)nH compounds with 4 ≦ n ≦ 14 melt by a two-step process. In the first step, the alkyl segment conformations gain nearly liquid like trans/ gauche ratios, while the perfluorinated segments remain ordered. “Gels” which incorporate the entire solvent are formed by crystallization from even dilute solutions of hydrocarbon and fluorocarbon solvents. The gels are built up of extremely long, interdigitated needles of the pure solute. Due to the bilayer structures and different degrees of ordering of the hydrocarbon and the fluorocarbon segments, the crystals grow preferentially in the direction parallel to the lamellar surface. Light scattering experiments in octane demonstrated the formation of micelle type associates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Variable temperature magic angle spinning 13C NMR experiments on linear alkanes and low molecular weight polyethylene allowed the observation of up to six carbon atoms at the chain ends near the surface of the lamellar crystallites. Conformational order-disorder and intermolecular packing effects are reflected by the spectra. The effects are discussed with regard to the peculiar phase behaviour of the n-alkanes and the fringed micella model for low molecular weight polyethylene. The solid-solid transitions of nonadecane and hexatriacontane appear to be correlated with the occurrence of specific non-liquid-like conformational disordering. Thus, conformational defects were observed for the “rotator phase” which depend on the chain length and which vary along the chain. Whilst the center part of the chain remains all-trans ordered, significant gauche defects were observed for the bonds at the chain ends. For a polydisperse low molecular weight linear polyethylene as well as for monodisperse octahexacontahectane reversible liquid-like conformational disordering of the terminal chain segments could be detected when the melting point was approached. Hence, in this case the NMR spectra indicate pre-melting of the lamella surface, while in case of the shorter n-alkanes the occurrence of end-gauche defects is correlated with solid-solid transitions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of AB diblock copolymers of poly(2-vinylpyridine) (P-2VP) and either polybutadiene or polystyrene were prepared in a nonpolar solvent at low temperature. Well-defined polymers with narrow molecular weight distributions were obtained and electron micrographs showed that these block copolymers form a well-separated two-phase morphology. Percolation of P-2VP domains could be achieved for samples with 40 and with 60 mol-% of P-2VP blocks. These samples were modified by addition of various amounts of iodine in solution and in the melt. Electric conductivities of the doped composites were determined by the four-probe method. The conductivities of the two phase systems were, in general, lower than that of P-2VP doped with I2.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 169-177 
    ISSN: 0887-624X
    Keywords: polysiloxane ; hexagonal columnar mesophase ; optically active polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly[(S)-(+)-2-methylbutyl]pentylsiloxane has been synthesized by anionic ring opening polymerization of the corresponding strained cyclic trisiloxane \documentclass{article}\pagestyle{empty}\begin{document}$ (D^{\rm{MeBu, Pe}}_{3}) $\end{document} with cryptated lithium (Li+/[211]) as counterion. The polymer did not show the low and high temperature crystalline phases, that are generally found for poly(di-n-alkylsiloxane)s. Instead, the material formed a hexagonal columnar mesophase until it melted around 400°C. MAS and solution 13C- and 29Si-NMR, polarizing microscopy and WAXS indicated an unexpectedly regular chain structure. It was tentatively concluded that the steric interaction of the (S)-(+)-2-methylbutyl side chains introduces sufficient regularity of the tacticity and that the chains tend to adopt a defect helix conformation. On the other hand, DSC showed the presence of a glass transition at -113°C, indicating a high flexibility of the backbone. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 169-177, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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