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Mesomorphic complexes through hydrogen bonding between alkoxy-substituted triarylmelamines and semiperfluorinated benzoic acids

: Kohlmeier, A.; Janietz, D.


Liquid crystals 34 (2007), No.3, pp.289-294
ISSN: 0267-8292
ISSN: 1366-5855
Journal Article
Fraunhofer IAP ()

The thermal behaviour of two 2,4,6-triarylamino-1,3,5-triazines carrying either three or six peripheral alkoxy chains have been investigated in binary mixtures with two-chain and three-chain partially fluorinated benzoic acids by means of polarizing microscopy, differential scanning calorimetry and X-ray scattering. The melamines form hydrogen-bonded aggregates with the complementary carboxylic acids. Each investigated equimolar mixture exhibits a hexagonal columnar mesophase. In the case of the six-fold alkoxy-modified triazine the individual columns are built up by descrete hetero-dimers with a circular cross- sectional shape. The segregation of fluorinated from lipophilic side chain regions leads to a superstructure within the hexagonal lattice. The hexagonal columnar phases of 1:1 compositions of the triazine, incorporating just three aliphatic chains with the semiperfluorinated benzoic acids, are formed by pairs of H-bonded dimeric supermolecules.