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Oligosaccharide‐based thermotropic liquid crystals, 4. Synthesis of cellobiose‐based twin and triplet derivatives and their mesophase properties
Author(s) -
Takaragi Akira,
Sugiura Makoto,
Minoda Masahiko,
Miyamoto Takeaki,
Watanabe Junji
Publication year - 1997
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1997.021980817
Subject(s) - mesophase , discotic liquid crystal , thermotropic crystal , columnar phase , crystallography , liquid crystal , alkyl , mesogen , monomer , phase (matter) , thermal stability , chemistry , materials science , molecule , polymer chemistry , organic chemistry , polymer , liquid crystalline , optoelectronics
Abstract Previous work from this laboratory has shown that cellobiose octaalkanoate (COA) functions as a thermotropic discotic mesogen, forming a hexagonal ordered columnar phase (D ho ). In this work, we prepared the COA‐based discotic twin and triplet derivatives and examined the mesomorphic properties of the derivatives by DSC, polarization microscopy and X‐ray diffraction. In the former derivative, two cellobiose heptadecanoate (CHD) molecules (monomers) are combined through an alkyl spacer of varying length by ether and ester linkages at the C‐1 position of the reducing end units of the monomers. Three CHD molecules having an alkyl spacer are connected with a coupling agent for the latter derivative. The results revealed that (i) all the twin derivatives form a distinct discotic columnar phase, (ii) the thermal stability of the mesophases of the twins is enhanced, compared with that of the monomer, when the length of the flexible spacer is appropriate, (iii) the twins with a relatively short spacer form a discotic rectangular ordered (D ro ) phase, while those with a longer spacer form a pseudo‐D ho phase, (iv) the triplets also form a discotic columnar mesophase, but not a hexagonal ordered columnar (D ho ) phase, (v) the thermal stability of the mesophases of the triplets strongly depends on the chemical nature of coupling cores, and (vi) the packing structures of the cellobiose cores within the columns of both derivatives are markedly different from that of the monomer.