«Comb-shaped LC stereoregular cyclolinear methylsiloxane copolymers:the synthesis and the behaviour in bulk and in monolayers». Liquid crystals 2012.V.39статья
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Дата последнего поиска статьи во внешних источниках: 20 марта 2017 г.
Аннотация:Stereoregular cyclolinear organosiloxane copolymers containing vinyl groups with diorganosiloxane spacers as well
as cyclohexasiloxane fragments were synthesised. Comb-shaped liquid crystalline (LC) cyclolinear polymethylsiloxanes
with mesogenic side groups were prepared by hydrosilylation of stereoregular cyclolinear organosiloxane
copolymers with (4-cyanobiphenyl-4-yl)-11-(1,1,3,3-tetramethyldisiloxyl)undecanoate in the presence of the
Karstedt catalyst. The chemical structure of the copolymers synthesised was confirmed by proton and silicon
nuclear magnetic resonance spectroscopies and infrared spectroscopy. Their phase behaviour was characterised
by differential scanning calorimetry, X-ray analysis and optical polarising microscopy. It was shown that the
appearance of the LC state, the temperature range of its existence and polymesomorphism are determined by
the molecular mass of the copolymer and by the content of the mesogenic groups. The introduction of three mesogenic
groups per monomer unit results in polymesomorphic transitions. The tacticity of the backbone influences
the interchain distances in the comb-shaped LC cyclolinear methylsiloxane copolymers. Studying the Langmuir
films of the stereoregular LC methylsiloxane copolymers revealed that different types of molecular arrangements
could be observed depending on the number of mesogenic groups attached. LC copolymers having three mesogens
per monomer unit demonstrate a two-stage monolayer collapse.