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Liquid Crystals and their Application
Russian Journal

Zhidkie kristally i ikh prakticheskoe ispol'zovanie

Жидкие кристаллы и их практическое использование

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Zhidk. krist. ikh prakt. ispol'z. = Liq. Cryst. and their Appl., 2008, 4, 15—25.





Synthesis and Properties Of Liquid Crystal Methylcyclotetrasiloxane Polymers with Side Mesogenic Cyanobiphenyl Groups



I. M. Petrova, A. V. Kaznacheev, P. V. Petrovsky, N. N. Makarova

Author affiliations
A. N. Nesmeyanov Institute of Organoelement Compounds RAS
Vavilova str. 28, 119991, Moscow, Russia

Abstract
New LC polymers with the main cyclolinear polymethylcyclotetrasiloxane chain and the side mesogen cyanobiphenyl groups from two to four united to the main chain across aliphatic –(CH2)10- and/plus tetramethyldisiloxane spacer were synthesized by the reaction of hydrosilylation cyclolinear polymethyl(vinyl)cyclotetrasiloxanes with 4'-cyanobiphen-4-yl-11-(tetramethyldisiloxyl)undecanoat. By the methods of IR, NMR 1H, 29Si spectroscopies, GPC, viscosimetry the cyclolinear structure of main chain and side groups LC polymers were established. By the method of DSC and polarizing optical microscopy the temperature and enthalpy of phase transitions were determined, it was shown that with the increase of the mesogen groups’ number in the LC polymer the temperature and enthalpy of all polymesomorphic transitions were raised. By the method of polarizing optical microscopy based on the texture appearance the formed smectic liquid crystals phases (SmA and SmC) were determined. The SAXS method showed that the interchain distance of LC cyclolinear polymethylsiloxane decreased from 50,01 to 44,80 Å with the increase of mesogen groups number in a polymer unit.

Keywords: liquid-crystalline polymer, cyclolinear polymethylsiloxane, hydrosilylation, platinum catalyst, mesogenic group, phase transitions, SAXS, polarizing optical microscopy





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