| Autor: |
Barmatov, E. B., Filippov, A. P., Shibaev, V. P. |
| Předmět: |
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| Zdroj: |
Liquid Crystals; Apr2001, Vol. 28 Issue 4, p511-523, 13p, 9 Black and White Photographs, 1 Chart, 13 Graphs |
| Abstrakt: |
Hydrogen-bonded blends based on smectic side group functionalized LC copolymers containing 4-alkyloxybenzoic acid fragments (proton donor) and a non-mesogenic low molecular mass dopant 4-cyanophenyl pyridine-4-carboxylate or 4-methoxyphenyl-d[sub 4] pyridine-4-carboxylate (proton acceptor) were obtained. The blends containing 10-35 mol % of low molecular weight dopant form nematic (I-N-SmA) or re-entrant SmA phases (I-SmA-N-SmAre). The temperature dependence of the order parameter S, the birefringence Δn, and the splay K[sub 1] and bend K[sub 3] elastic constants of the nematic phase were studied by [sup 2]H NMR spectroscopy and the Fréedericksz method of threshold transitions in a magnetic field. A mechanism for the destruction of the SmA phase and the formation of the nematic phase in the hydrogen-bonded blends is suggested. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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