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  • 11
    Electronic Resource
    Electronic Resource
    A comparative study of the conformational mobility of octamethyltetrasiloxane and cyclododecane in the solid state (1984)
    Springer
    Polymer bulletin 12 (1984), S. 557-563 
    Details
    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 A crystalline mesophase state in which molecules show conformational mobility is discussed for cyclododecane and octamethyltetrasiloxane.13C and29Si solid state NMR spectra show changes of the resonance signals which can be explained by changes of the conformation. The transition temperatures in the NMR spectra are correlated with the thermal transitions detected by DSC. Comparisons with the solution spectra give evidence that in case of octamethyltetrasiloxane, the conformational mobility is determined mainly by the molecular packing in the crystal, while packing effects are neglegibly small for cyclododecane. The data are discussed with concern to the corresponding linear chain molecules, i. e. poly(ethylene) and poly(dimethylsiloxane).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958664
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  • 12
    Electronic Resource
    Electronic Resource
    Microphase separated semi-interpenetrating polymer networks from atactic polystyrene and methacrylates — a novel route (1992)
    Springer
    Polymer bulletin 27 (1992), S. 681-688 
    Details
    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: Summary A new route towards the formation of micro-phase separated semi- interpenetrating polymer networks (semi-IPN's) is described for the system atactic PS in methacrylates. It comprises the arrest of spinodal decomposition of an aPS solution by thermoreversible gelation (vitrification) of the polymer-rich phase. After lowtemperature UV-polymerization and crosslinking of the methacrylate, the phase separated structure is preserved at room temperature. Thus the steps of morphology formation and polymerization are separated. The demixing and gelation behaviour of solutions of atactic PS in several n-alkyl and branched methacrylates was studied. Gelation temperatures were found to be determined by the position of the demixing curves along the temperature axis and thereby the intersection points with the glass transition-concentration curve of plasticized PS. At polystyrene concentrations of 2 and 5 wt% a bicontinuous microphase separated morphology could be obtained with domain sizes of 0.2–0.5 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297439
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  • 13
    Electronic Resource
    Electronic Resource
    Poly[(S)-(+)-2-methylbutyl]pentylsiloxane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 169-177 
    Details
    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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  • 14
    Electronic Resource
    Electronic Resource
    Molecularly thin films of metallodendrimers (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 540-545 
    Details
    ISSN: 0894-3230
    Keywords: metallodendrimers ; molecularly thin films ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A non-covalent synthesis route to assemble metallodendrimers was extended to the fifth generation. Generation four (G4) was characterized by electrospray mass spectrometry. Thin films of generation five (G5) metallodendrimers were studied by tapping mode scanning force microscopy. Both on graphite and on mica spherical particles with a diameter of ca 15 nm were observed. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Micellar morphology of a semifluorinated diblock copolymer (1998)
    Springer
    Polymer bulletin 40 (1998), S. 211-217 
    Details
    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
    URL: http://dx.doi.org/10.1007/s002890050244
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  • 16
    Electronic Resource
    Electronic Resource
    New carbohydrate amphiphiles, 2.Part 1: cf. ref.15b Gel formation and gel morphologies (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2379-2384 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The physical gelation of 3,4,5-trialkoxy-N-(1-deoxysorbitol-1-yl)benzamides and 3,4,5-trialkoxy-N-(2-deoxyglucos-2-yl)benzamides in organic solvents and monomeric methacrylates at ambient temperature is reported. UV polymerization of the methacrylate solvent yielded interpenetrating networks of the crosslinked polymethacrylate and the aggregated solute. The embedded gels exhibit two different morphologies depending on the solvent. Either white/turbid gels containing a percolating network of globular aggregates (φ = 1-10 μm) or clear, transparent gels consisting of rod-like crystals (φ = 4-100 nm) were found. The sphere morphology consists of small rod-shaped crystallites assembled to spherical objects and is assumed to be caused by a liquid-liquid demixing process prior to gelation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Determination of configuration and conformation of polymer segments by low-molecular-weight diastereomeric model compounds (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 823-827 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790325
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  • 18
    Electronic Resource
    Electronic Resource
    Phase transitions and defect structure in the lamellar surface of polyethylene and n-alkane crystallites. Magic angle spinning 13C NMR studiesHerrn Professor Dr. R. Kosfeld zum 60. Geburtstag gewidmet (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1237-1252 
    Details
    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
    URL: http://dx.doi.org/10.1002/macp.1986.021870520
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  • 19
    Electronic Resource
    Electronic Resource
    Melting, crystallization, and solution behavior of chain molecules with hydrocarbon and fluorocarbon segments (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 911-925 
    Details
    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
    URL: http://dx.doi.org/10.1002/macp.1988.021890422
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  • 20
    Electronic Resource
    Electronic Resource
    Poly(2-vinylpyridine) block copolymers. Phase separation and electric conductivity of iodine complexesDedicated to Prof. Dr. H.-J. Cantow on the occasion of his 65th birthday (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 1153-1168 
    Details
    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
    URL: http://dx.doi.org/10.1002/macp.1989.021900521
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