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Novel atropisomeric binaphthol containing comb‐shaped copolymers forming chiral nematic phases
Author(s) -
Shibaev V. P.,
Deussen H. J.,
Bobrovsky A. Yu.,
Shibaev P. V.,
Boiko N. I.,
Bjørnholm T.,
Schaumburg K.,
Bechgaard K.
Publication year - 1997
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11738
Subject(s) - copolymer , monomer , materials science , chirality (physics) , liquid crystal , polymer , polymer chemistry , molecule , mesophase , comonomer , atropisomer , crystallography , organic chemistry , composite material , chemistry , chiral symmetry breaking , physics , optoelectronics , quantum mechanics , nambu–jona lasinio model , quark
Novel comb‐shaped liquid crystalline acrylic copolymers consisting of nematogenic methoxy‐phenylbenzoate acrylic monomers (A) together with novel chiral binaphthol (BN) methacrylic monomers (MB‐ m ) were synthesized in this study. The prepared copolymers differ in spacer lengths of MB‐ m ( m = 3, 5, 11) and in their compositions. The homopolymers of the three new chiral BN monomers MB‐ m were also prepared. Copolymers with a low concentration of BN monomeric units (less than 16 mol %) display a cholesteric mesophase. The induced chirality in the polymers is due to atropisomerism (chirality due to hindered rotation around single bonds) of the BN molecules. The helical twisting power β (HTP) caused by the atropisomeric units in the synthesized copolymers was shown to decrease significantly on heating. The unusually high negative temperature coefficient of HTP observed above the glass transition temperature ( T g ) could be explained in terms of conformational changes of the BN molecules in the copolymers.