Fluoroalkylated discotic liquid crystals

Abstract The concept of mesophase stabilization by partial fluorination of side chains has been extended to discotic systems. The mesophase structure is essentially unchanged, whereas the temperature range of the mesophase is strongly affected by the fluorinated side chains. Triphenylene substituted with only one partially fluorinated side chain exhibits a decrease of the clearing temperature, whereas for symmetrically substituted systems a broad range mesophase has been observed. This behaviour can be attributed to a segregation of the incompatible parts of the molecule giving rise to a stabilized columnar structure for the symmetrical substitution pattern.

Micellar and lyotropic behavior of three isomeric bola-amphiphiles with pyridinium groups

The micellar and lyotropic phase behavior of three isomeric bola-amphiphiles 1, 2 and 3 based on para-, meta- and ortho-phenylene derivatives with hydrophilic pyridinium headgroups was investigated. The micellar behavior was characterized by surface-tension and conductivity measurements: while the para-substituted amphiphile 1 and the ortho isomer 3 aggregated to micelles, the meta-substituted amphiphile 2 exhibited stepwise, but discontinous self-association. This is explained by the mass-action and phase-separation model. The existence of “premicellar” aggregates and the discontinous aggregation of 2 is evidenced in addition by a difference-spectro-photometric measurement. The low surface…

The synthesis and the thermotropic phase behavior of the dipolar amphiphiles C 5 H 5 N + (CH 2 ) m OCOPhPHCOO(CH 2 ) m N + C 5 H 5 and the polymeric amphiphile [(CH 2 ) 6 OPhPhO(CH 2 ) 6 OCOCH([CH 2 ] 6 N + C 5 H 5 )COO] n are described