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Liquid crystalline poly(enamine ketone)s formed through hydrogen bonding
Author(s) -
Yandrasits Michael A.,
Zhang Anqiu,
Bruno Katie,
Yoon Yeocheol,
Sridhar Krishnamurthy,
Chuang Yuhway,
Harris Frank W.,
Cheng Stephen Z. D.
Publication year - 1994
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1994.210330108
Subject(s) - intramolecular force , enamine , liquid crystal , polymer , mesogen , ketone , hydrogen bond , crystallography , quenching (fluorescence) , phase (matter) , materials science , crystallization , liquid crystalline , chemistry , polymer chemistry , stereochemistry , organic chemistry , molecule , catalysis , physics , optoelectronics , quantum mechanics , fluorescence
A series of poly(enamine ketone)s (PEAKs) which exhibit liquid crystalline phases has been synthesized. The enamine ketone groups are able to exist in the cis and trans conformations. Molecular modelling results show that the cis conformation is energetically more favorable due to intramolecular hydrogen bonding. Model compound studies indicate that the formation of the mesogen requires the cis conformation in the enamine ketones to stabilize the liquid crystalline phase. This liquid crystalline phase is nematic for the model compound and the polymers. The heats of liquid crystal transition in the model compound and in PEAKs are very close (4.7 kJ/mol in model compound and 4.0 kJ/mol of repeating units in polymers). This is not only an indication of a similar percentage of the cis conformation in both cases, but also an example that the flexible ethyleneoxy spacers in the polymers do not contribute to the orientational order of this liquid crystalline phase. PEAKs can crystallize through either quenching from the isotropic melt or from the liquid crystalline phase. Crystallization kinetics exhibit the effect of pre‐ordering when these two different kinetics are compared.