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Thermotropic Perfluoroalkyl Azobenzoates. Studies of Low Molar Mass Compounds and Side Chain Polymer Derivatives

 

作者: Xujin Bao,   LeslieR. Dix,  

 

期刊: Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals  (Taylor Available online 1999)
卷期: Volume 333, issue 1  

页码: 25-33

 

ISSN:1058-725X

 

年代: 1999

 

DOI:10.1080/10587259908025993

 

出版商: Taylor & Francis Group

 

关键词: Perfluoroalkylated liquid crystals;Thermotropic Azobenzene compounds;Side chain liquid crystal polymers

 

数据来源: Taylor

 

摘要:

A series of 4′-[(carbonyloxy-1,1,2,2-Tetrahydrofluorodecyl)]-4-(ω-bromo-alkenyloxy) azobenzenes. 4′-[(carbonyloxy-l,1,2,2-Tetrahydrofluorodecyl)]-4-(alk-l-enyloxy) azobenzenes have been synthesised. Also, a polyacrylate has been formed by phase transfer catalysed reaction between one of the ω-bromo-alkenyloxy compounds and sodium polyacrylate as well as two polysiloxanes formed by hydrosilylation of the alkenyloxy compounds and a polyhydrosilane. All of the low molar mass compounds show the SAphase on heating and an increase in perfluoroalkyl chain length results in an increase in clearing temperature whilst an increase in the hydrocarbon chain length shows a decrease in clearing temperature. Upon grafting these low molar mass units to a polymer backbone, the resulting materials also show smectic mesophases despite having quite low clearing entropies (ΔS/R ∼ 0.2 – 0.6). The precursor polymers are of low molar mass (Mw 1200-1800 g mol-1) and this may be the reason why the polymers do not show glass transition temperatures.

 

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