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  • 1
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The role of components in MoOCl4-based living polymerization catalysts was studied. The MALDI TOF MS spectra of the poly(o-[(trifluoromethyl)phenyl]acetylene)s prepared with n-Bu4Sn and Et3Al as cocatalysts suggested a difference of 28(C2H4) in polymer molecular weight. This indicates that the formed polymer possesses an alkyl group of cocatalyst in the initiating chain end, which implies the transalkylation between MoOCl4 and a cocatalyst and the subsequent formation of a Mo carbene. Sterically uncrowded aliphatic alcohols were useful as the third catalyst components. Addition of EtOH to the catalyst system led to the increase of activation enthalpy and the change of activation entropy from a negative to positive value in the propagation reaction, which suggests that EtOH coordinates to the propagating end competitively with the monomer.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1042-7147
    Schlagwort(e): LBK films ; alternating layers ; ionenes ; NLO chromophores ; surface plasmon spectroscopy ; X-ray reflection and diffraction ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: 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.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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