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  • Chemistry  (39)
  • Stability of LB Films  (1)
  • Langmuir-Blodgett assemblies
  • Physics
  • 1990-1994  (39)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Structure and mechanical properties of films of rigid-rod polymers having flexible side chains (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 11-30 
    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 rigid-rod polyesters with flexible alkoxy side chains of different length has been studied in order to determine the structure and properties of the polymers in various states (solid state, mesophase, melt). Various supermolecular structures can be obtained depending on the length of the side chains and on the preparation conditions of the samples. The relaxation behavior of the polymers has been investigated by dynamic mechanical measurements. Complex relaxation spectra have been observed, and types of molecular motions and structural rearrangements have been assigned to the observed mechanical relaxation transitions. The rheological behavior was studied in the mesophase and in the melt. In some polymers typical liquid-crystalline properties have been observed, as for example the flow-thinning effect. Large deformation of polymer films as well as the structure and mechanical strength of oriented samples have also been studied.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930102
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  • 2
    Electronic Resource
    Electronic Resource
    A new radical cation salt: Electrocrystallization of trans-1,2-bis(2-naphthyl)ethene and model character of the resulting salt for conducting arylenevinylene polymers (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 575-582 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A single-crystal radical cation salt was obtained by anodic oxidation of trans-1,2-bis-(2-naphthyl)ethene (1,2-DNE) with SbF-6 as the counter-ion. The crystal structure of (1,2-DNE)SbF6 was solved and found to be similar to the radical cation salts of unsubstituted naphthalene. The crystal structure is disordered, i.e. two orientations of the 1,2-DNE molecules are statistically occupied. The molecular overlap, resulting from these two orientations, models the structure of the salt of poly(2,6-naphthylenevinylene). In contrast to most other radical cation salts which are one-dimensional conductors, a conduction mechanism of higher dimensionality is predicted on the basis of the crystal structure of (1,2-DNE)SbF6. The identical type of disorder is also present in the crystal structure of trans-1,2-bis(1-naphthyl)ethene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930302
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  • 3
    Electronic Resource
    Electronic Resource
    Steric effects in 3-substituted polythiophenes: comparing band gap, nonlinear optical susceptibility and conductivity of poly(3-cyclohexylthiophene) and poly(3-hexylthiophene) (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1195-1206 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We present the synthesis, characterization (NMR, mass spectroscopy, IR) and polymerization of 3-cyclohexylthiophene. Although anodic polymerization is ineffective, it was possible to polymerize 3-cyclohexylthiophene with FeCI3 as the oxidizing reagent, the resulting poly(3-cyclohexylthiophene) (PC6T) having a peak molar mass of 73 000 g · mol-1. NMR-Investigations reveal that the coupling ocurred mainly via the 2,5-positions, and the band gap, as determined from UV-vis spectroscopy and cyclic voltammetry, was 2,3-2,4 eV. The nonlinear susceptibility χ(3)(-3ω; ω ω ω) of the neutral polymer and the electrical conductivity of the CIO4- and PF-6 salts were determined. The effect of the steric requirements of the cyclohexyl substituent was estimated by comparing the polymer to a poly(3-hexylthiophene) (PN6T) of the same molar mass and with a comparable number of defects (mainly head-to-head and tail-to-tail coupling of the subunits). In the case of PC6T the band gap of the neutral polymer is larger by 0,3 to 0,4 eV, the nonlinear susceptibility has approximately half the value, and the electrical conductivity of the oxidized polymer is two orders of magnitude lower than the corresponding values of PN6T. These effects are explained by the increased sterical requirements of the cyclohexyl substituent, which forces the thiophene rings out of a coplanar conformation and thus reduces the conjugation length.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930516
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  • 4
    Electronic Resource
    Electronic Resource
    Langmuir-Blodgett mono- and multilayers of preformed poly(octadecyl methacrylate)s, 2.Part 1: cf. ref.1 Structural studies by IR spectroscopy and small-angle X-ray scattering (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 2215-2229 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Langmuir-Blodgett (LB) mono- and multilayers of preformed atactic and isotactic poly(octadecyl methacrylate)s were studied on gold surfaces and silicon wafers. The average orientation of the carbonyl bond of the ester group was found to be about 50° with respect to the normal to the substrate, and the side chains were concluded to be oriented perpendicular to the substrate. Furthermore, the degree of side chain orientation increased on going from a single monolayer to a multilayer. This is explained by an interdigitation of the side chains during or after the transfer process. A peculiar transfer behavior of the atactic samples is discussed in terms of the effect of disorder of the first layer on the transfer process. On heating multilayers of the polymers, melting of the crystalline domains formed by the side chains was observed at temperatures of about 35°C to 40°C. However, the layer structure appeared to be stable up to 100°C. The oriented structure was completely recovered after cooling down to room temperature.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021921003
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of telechelic poly(p-phenylene) derivatives (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1021-1029 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of oligo(2,5-dialkyl-p-phenylene)s bearing terminal boronic acid, bromo-,acetoxy-, methoxycarbonyl- or carbonic acid groups is reported. Oligomers of number-average degree of polymerization 6 ≤ Pn ≤ 20 were obtained by the palladium-catalyzed coupling of aromatic halides with aromatic boronic acids. The same synthetic approach was used to prepare derivatives of p-terphenyl, bearing hydroxy-, acetoxy-, carboxy- or amino-groups in 4,4″-position.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930418
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  • 6
    Electronic Resource
    Electronic Resource
    A novel synthetic route to rigid-rod polyimides (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1847-1858 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new synthetic approach to soluble, rigid-rod, aromatic polymides is described. The polycondensation is done by a Pd-catalyzed aryl-aryl coupling of N,N′-bis(4-bromo-2,5-didodecyl-phenyl)-1,2:4,5-pyromellitic diimide (2) and 2,5-didodecyl-1,4-benzenediboronic acid (3). Here, the imide structure is already preformed in monomer 2. A structurally identical polymer is synthesized by the classical procedure condensing 1,2:4,5-pyromellitic dianhydride (PMDA) (4) and 4,4″-diamino-2,5,2′,5′,2″,5″-hexadodecyl-p-terphenyl (5). Both polymers are characterized in detail by 1H and 13C NMR spectroscopy, membrane osmometry and size exclusion chromatography. The average degree of polycondensation is of the order of 15. The thermal behaviour of the polymers is studied by differential scanning calorimetry and thermogravimetrical analysis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930806
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  • 7
    Electronic Resource
    Electronic Resource
    Structural study of the aging and thermal evolution of polyiodide chains in doped trans-polyacetylene (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 853-864 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The evolution of the structure of iodine chains in iodine-doped polyacetylene has been followed as a function of temperature. It is shown that these chains exhibit a disorder of the second kind characterized by the lack of long-range order in chain direction. A low-temperature improvement of intra-chain order demonstrates that a substantial part of this disorder is thermal in nature. A parallel is drawn to similar effects frequently observed in crystalline iodine chain organic charge transfer salts. Furthermore, fresh samples with a nominal composition CHI0,24 are unstable under the X-ray beam. They exhibit a slow transition toward an apparently stable form corresponding to CHI0,19. The diffraction pattern in chain direction of this form can be quantitatively explained with a simple model using triiodide chains only. A comparison with other models proposed in the literature is made.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930404
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and properties of polyesters derived from 2′,5′-dialkyl-p-terphenyl-4,4″-diol (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1031-1041 
    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 polyesters based on 2′,5′-dihexyl-p-terphenyl-4,4″-diol as one component and various aliphatic or aromatic diacids as the second component have been synthesized. The polyesters are soluble and film forming. Materials based on the terphenyldiol and terephthalic acid or the terphenyldiol and 2′,5′-dihexyl-p-terphenyl-4,4″-dicarboxylic acid show a temperature dependence of the elastic modulus between 100 and 300°C resembling the behavior of hard elastic polymers, Glass transition phenomena in the conventional sense were not observed. The materials exhibit good mechanical properties up to temperatures well above 300°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930419
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  • 9
    Electronic Resource
    Electronic Resource
    Copolymers of ethyl p-vinylbenzenesulfonate for the preparation of polyelectrolytes of reproducible ion content (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1237-1248 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethyl p-vinylbenzenesulfonate (ESS) for which a new synthesis is described has been copolymerized with vinylcarbazole, styrene, p-methylstyrene and p-bromostyrene in N,N-dimethylformamide at 60°C using azoisobutyronitrile as initiator. Copolymer compositions and copolymerization parameters have been evaluated. Q, e-values for ESS are 4,19 and -0,11. Thermal properties of the copolymers have been investigated by differential scanning calorimetry and thermogravimetric analysis. Polyelectrolytes have been prepared either by polymer analogous hydrolysis of the sulfonic acid esters followed by conversion of the free acids into alkali metal salts or by using the alkylating properties of the esters towards tertiary amines or pyridines to form the appropriate sulfonic acid ammonium or pyridinium salts. The latter method offers the opportunity to synthesize polyelectrolytes with a well defined content of chromophores.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940417
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  • 10
    Electronic Resource
    Electronic Resource
    Soluble poly(para-phenylene)s, 3.Part 2: cf. 1. Variation of the length and the density of the solubilizing side chainsDedicated to Dr. A. Hüthig on the occasion of his 90th birthday (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1991-2003 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of a variety of alkyl-chain-substituted poly(para-phenylene) (PPP) derivatives, including those with systematically decreased density of side chains, is described, using for their preparation the Pd-catalyzed polymerization method recently developed in Mainz (Mainz route to PPP's). The degrees of polymerization achieved range between 30 and 50, allowing the synthesis of structurally well-defined and soluble PPP's with more than hundred 1,4-phenylene rings attached to each other.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910902
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