Self-assembly of amphiphilic liquid-crystalline oligomers possessing a semiperfluorinated alkyl chain

Amphiphilic liquid-crystalline oligomers composed of a semiperfluorinated alkyl chain and cyanobiphenyl mesogenic moieties were prepared. Their physical properties were investigated using optical microscopy, differential scanning calorimetry, and X-ray diffraction measurements. The oligomers were found to show an unusual phase sequence of lamellar-columnar-bicontinuous cubic phases when the number of cyabobiphenyl moieties was increased. Results of the XRD study suggest that the smectic A phase of the oligomer with a SmA to Cub phase transition has an undulated layer structure. We discuss effects of the molecular structure on the appearance of the columnar and cubic phases of the novel liquid crystal oligomers.