Liquid‐crystalline polyethers and copolyethers based on conformational isomerism, 5.Thermotropic copolyethers based on 1‐(4‐hydroxyphenyl)‐2‐(2‐methyl‐4‐hydroxyphenyl)ethane and flexible spacers containing odd and even numbers of methylene units
作者:
Virgil Percec,
Raymond Yourd,
期刊:
Die Makromolekulare Chemie
(WILEY Available online 1990)
卷期:
Volume 191,
issue 1
页码: 49-69
ISSN:0025-116X
年代: 1990
DOI:10.1002/macp.1990.021910104
出版商: Hüthig&Wepf Verlag
数据来源: WILEY
摘要:
AbstractThe synthesis and characterization of thermotropic main‐chain liquid‐crystalline copolyethers based on 3‐methyl‐4,4′‐ethylenediphenol [1‐(4‐hydroxyphenyl)‐2‐(2‐methyl‐4‐hydroxyhenyl)‐ethane (MBPE)], which is a flexible rod‐like mesogenic unit or a rod‐like mesogenic unit based on conformational isomerism, and pairs of flexible spacers containing odd and even numbers of methylene units,X,Y, i.e., MBPE‐X/Y, whereX/Y= 5/12, 5/10, 5/8, 6/11, 6/9, 4/11 and 4/9, are described. Copolymerization decreases the rate of crystallization and subsequently transforms virtual or monotropic mesophases of homopolymers into monotropic or even enantiotropic mesophases. Both liquid‐crystalline transition temperatures and enthalpy changes of the identical mesophases displayed by copolymers represent weight‐averaged values of the similar parameters of the parent homopolymers. Their extrapolation leads to the determination of the virtual mesomorphic transition temperatures and enthal
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