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  • 1995-1999  (49)
  • 1970-1974  (33)
  • General Chemistry  (42)
  • Polymer and Materials Science  (40)
  • 1
    Electronic Resource
    Electronic Resource
    The photovoltaic stability of, bis(isothiocyanato)rlutheniurn(II)-bis-2, 2′bipyridine-4, 4′-dicarboxylic acid and related sensitizersSupport of this work by the european joule III program is gratefully acknowledged. (1997)
    Weinheim : Wiley-Blackwell
    Advanced Materials 9 (1997), S. 904-906 
    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: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19970091111
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of polyimides endcapped with phenylethynylphthalic anhydride (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2141-2149 
    Details
    ISSN: 0887-624X
    Keywords: polyimides ; 4-phenylethynylphthalic anhydride ; thermooxidative stability ; high-temprature MAS NMR ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of high glass transition temperature (Tg 〉 300°C), amorphous, soluble, poly-imide oligomers of controlled molecular weight endcapped with 4-phenylethynylphthalic anhydride endcapping agent is described. The 4-phenylethynylphthalic anhydride was employed to afford a higher curing temperature (380-420°C) which widens the processing window compared to unsubstituted acetylene-endcapped polyimides. The polyimides were synthesized via solution imidization techniques, using the ester-acid of various dianhydrides and aromatic diamines. A “ one-pot” procedure utilizing NMP as the solvent and o-dichlo-robenzene as the azeotroping agent reproducibly produced fully imidized, but yet soluble wholly aromatic polyimides. Thermally cured samples were prepared with gel contents of up to 98% that displayed good solvent resistance. Glass transition temperatures comparable to high molecular weight linear analogs were produced. These polyimides also show excellent thermal stability as judged by thermogravimetric analysis (TGA). Model phenylethynyl imide compounds were synthesized and used to follow and elucidate the nature of the products formed from the phenylethynyl curing by using high temperature magic-angle 13C nuclear magnetic resonance (MAS NMR). Preliminary results indicate that the cure reaction can be followed by MAS NMR. However, the nature of the products being formed during the curing process is difficult to determine by the solid-state MAS NMR alone. Differential scanning calorimetry (DSC) data clearly show that the model system does indeed melt and displays a wide window before the strong cure exotherm is observed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331307
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Morphology development during the polymerization of styrene within a polyurethane network: Investigations by small-angle X-ray and light scattering (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 295-302 
    Details
    ISSN: 1042-7147
    Keywords: interpenetrating polymer networks ; kinetics ; phase separation ; X-ray scattering ; light scattering ; polyurethane ; polystyrene ; 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
    Notes: Phase separation that takes place during the formation of semi-interpenetrating polymer networks based on crosslinked polyurethane and linear polystyrene was studied by small-angle X-ray scattering and light scattering. The kinetics of the chemical reactions was followed by Fourier transform infrared spectroscopy. The occurrence of broad peaks in the X-ray scattering curves was interpreted in terms of distances between the urethane crosslinks. Small modulations on these curves were assigned to sphere-like structures with a diameter of around 5 nm which might be related to the urethane crosslink regions. Small modulations on the light-scattering curves at the beginning of styrene polymerization were assigned to spheres with diameters of around 4.5 μm, which can be related to the polystyrene-rich phase. These modulations disappear with time, which might indicate an increasing polydispersity of the domain sizes. The final morphology was found to depend on the time at which polymerization of styrene is initiated with respect to the time of gelation of polyurethane.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Influence of central metal and ligand system on conduction type and charge carrier transport in phthalocyanine thin films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 6 (1996), S. 239-244 
    Details
    ISSN: 1057-9257
    Keywords: molecular semiconductors ; organic semiconductors ; phthalocyanines ; conductivity ; thermopower ; seebeck effect ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: By changing the chemical composition of phthalocyanine molecules, the electrical properties of the ensemble in the solid state can be influenced directly. This is shown for phthalocyaninatomanganese (PcMn) as compared with purely divalent central metals and for complexes in which the ligand system has been modified by either electron-withdrawing heteroatoms such as N instead of CH leading to tetrapyridotetraazaporphyrinatozinc (TPyTAPZn) or substituents such as F instead of H leading to hexadecafluorophthalocyaninatozinc (F16PcZn). The accessibility of additional oxidation states of Mn or the stabilisation of frontier orbital states by the ligand leads to a lower ionisation potential and interactions with impurities or dopant molecules are changed. A change in the observed majority carrier (n-type behaviour) is seen even under UHV conditions. Measurements of the thermoelectric power and electrical conductivity are presented of the pure films and after exposure to oxidising ambient. During film growth either island growth or a growth following the Stranski-Krastanov mechanism was observed. The comparison of the temperature dependence of thermopower and electrical conductivity leads to a discussion of the type of majority carriers, their generation as well as their transportation. For the materials investigated in this study the band model fails to explain the observed properties and a localised transport mechanism has to be considered. A transport in localised states close to the Fermi edge is discussed for TPyTAPZn and F16PcZn.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Langmuir-Blodgett-Kuhn multilayer assemblies of NLO active amphiphiles and ionene polymers: Importance of complementary charges (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 571-576 
    Details
    ISSN: 1042-7147
    Keywords: LBK films ; alternating layers ; ionenes ; NLO chromophores ; surface plasmon spectroscopy ; X-ray reflection and diffraction ; 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
    Notes: Langmuir-Blodgett-Kuhn films of ionene polymers and nonlinear optically (NLO) active amphiphiles were investigated using several ultrathin film-sensitive techniques to determine multilayer ordering. Studies involved the formation of “passive-active” AB y-type multilayers of the ionenes and the NLO active amphiphiles. Deposition was possible with the use of an alternate three compartment dipping trough. The multilayer structures and thicknesses were verified by X-ray diffraction and reflection measurements and surface plasmon spectroscopy on a gold-coated glass substrate. Two main factors were determined to be responsible for the formation of stable alternating film architectures, namely electrostatic interaction in the hydrophilic layers and the van der Waals interaction in the hydrophobic layers. The use of ionenes as a class of amphiphilic polymers allowed the preparation of films with excellent optical quality.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of diblock and homopolymer impurities on the morphology of triblock polymers (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 2079-2089 
    Details
    ISSN: 0021-8995
    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
    Notes: Commercial triblock polymers (Kratons) consisting of polystyrene and a polydiene were characterized via gel permeation chromatography and small-angle x-ray scattering in order to determine the amount of free polystyrene and diblock material and to clarify the effect of these polymeric impurities on the morphology of solvent-cast samples. Gel permeation chromatography measurements revealed the Kratons to consist of 80-85% triblock, 15-20% diblock, and trace amounts of free polystyrene. Pure triblocks, impurity-doped pure triblocks, the Kratons, and a postpolymerically degraded Kraton were examined with regard to the effect of polymeric impurities on morphology. Small amounts (〈5%) of free polystyrene induce a regularization of the glassy domains, while increased amounts of this homopolymer apparently lead to diffuse phase boundaries. The presence of diblock polymer results in a loss of macrolattice details, indicating the presence of less ordered and more diffuse glassy domains.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160819
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  • 7
    Electronic Resource
    Electronic Resource
    Enantioselective Lithiation and Substitution of (E)-Cinnamyl N,N-Diisopropylcarbamate through Use of (-)-Sparteine Complexes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2397-2403 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Chiral allylic anions ; (-)-Sparteine ; Enantioselective deprotonation ; Stereochemistry of electrophilic allylic substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction leads to diastereomeric lithium carbanion pairs that are configurationally unstable and equilibrate even at temperatures below -50 °C. The initially formed epimer (1S)-epi-10 is rapidly converted to the thermodynamically more stable (1R)-10 (in toluene solution). Carboxylation, acylation with acid chlorides, stannylation, and silylation take place at the α-position with stereoinversion (79-86% ee). Methylating agents attack the γ-position; here, the stereochemical course depends on the leaving group, anti-SE′ for the iodide (50% ee) and syn-SE′ (48% ee) for the tosylate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Electrosynthesis of Aromatic Aldehydes by Palladium-Catalyzed Carbonylation of Aryl Iodides in the Presence of Formic Acid (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1471-1473 
    Details
    ISSN: 1434-193X
    Keywords: Palladium ; Homogeneous catalysis ; Carbon monoxide ; Aromatic aldehyde ; Formic acid ; Carbonylation ; Electrochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The palladium-catalyzed electrocarbonylation of aryl halides performed in the presence of formic acid under one atmosphere of carbon monoxide affords aromatic aldehydes in good to high yields.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Vinyl- and Divinylcyclopentadienes by Rhodium-Catalyzed Condensation of Alkynes with Cross-Conjugated Amino Metallahexatrienes [= (1-Amino-1,3-butadien-2-yl)carbene Complexes] (M = Cr, W) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2545-2561 
    Details
    ISSN: 1434-193X
    Keywords: Carbene complexes ; Catalysis ; Metallahexatrienes ; Vinyl cyclopentadienes ; Transmetallation ; Rhodium ; Tungsten ; Chromium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report on the first example of a transition metal-catalyzed cyclization reaction of a Fischer carbene complex. It comprises the generation of vinyl- and divinyl cyclopentadienes under exceedingly mild conditions at 20 °C by condensation of (1-amino-1,3-butadien-2-yl)carbene complexes (= cross-conjugated metallahexatrienes) (CO)5M=C(OEt)C(=CHNR2)CR1=CHR23 (M = Cr, W) with alkynes R3C≡CH 4 (R3 = Ph, cyclohex-1-enyl, isopropenyl, methoxymethyl, 1-trimethylsiloxycyclohex-1-yl) in the presence of catalytic amounts of [(COD)RhCl]2. The starting compounds 3 are accessible in high yields by addition of enamines (E)-R2NCH=CHR22 to (1-alkynyl)carbene complexes (CO)5M=C(OEt)C≡CR11 (M = Cr, W; R1 = Ph, cyclohex-1-enyl).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Clusters on Clusters: closo-Dodecaborate as a Ligand for Au55 Clusters (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2051-2055 
    Details
    ISSN: 1434-1948
    Keywords: Gold clusters ; closo-Dodecaborate ; Conductivity ; Charging energy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The exchange of PPh3 in Au55(PPh3)12Cl6 by Na2[B12H11SH] using a phase-transfer reaction from CH2Cl2 to water needs 6 weeks for reaction, but finally results in the quantitative formation of Au55[(B12H11SH)Na2]12Cl6 (2). Cluster 2, which is of considerable stability in aqueous solution, has been characterized by 1H-NMR, 11B-NMR, and IR spectroscopy as well as by transmission electron microscopy (TEM). The Na+ cations can be exchanged by (octyl)4N+ making the resulting cluster 4 soluble in polar organic solvents. The electrical properties of 2 and 4 are compared with those of Au55[Ph2PC6H4SO3N(octyl)4]12Cl6 (3), the ammonium derivative of the sodium salt. Cluster 3 shows the expected increase of activation energy in the temperature range of 130-250 K owing to the increase of cluster spacing compared with the sodium derivative. However, clusters 2 and 4, show electromigration in the electric field, caused by the huge amount of ionic charges in the ligand shell.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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