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Mesophase Morphologies of Hydrogen-Bonded Complexes of Biphenyl-Substituted Diamino-1,3,5-triazines with Semiperfluorinated Benzoic Acids

: Vlad-Bubulak, T.; Buchs, J.; Kohlmeier, A.; Bruma, M.; Janietz, D.


Chemistry of Materials 19 (2007), No.18, pp.4460-4466
ISSN: 0897-4756
ISSN: 1520-5002
Journal Article
Fraunhofer IAP ()

Two 2,4-diamino-6-biphenyl-4-yl-1,3,5-triazines carrying either one semiperfluorinated or two lipophilic alkoxy chains at the terminal position of the biphenyl moiety 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 diffraction. Equimolar compositions of the triazines with the complementary two-chain benzoic acid form descrete hydrogen-bonded heterodimers. The dimeric supermolecules organize to rectangular columnar phases in the c2mm plane group. The Colr phases are composed of infinite ribbons of parallel aligned H-bonded rigid polar cores which are separated by aliphatic/ fluorinated regions. H-bonded associates of the fluorinated triazine with three equivalents of the twochain acid form a rectangular columnar phase (p2m symmetry). Replacing the one fluorinated chain of the triazine by two alkoxy groups leads to a columnar phase o n a two-dimensional square lattice (p4mm) in a 1:3 mixture with the two-chain benzoic acid. The 1:3 mixed systems of the triazines with the three-chain aromatic acid display micellar cubic phases.