Figures & data
Figure 1 Discotic star oligomer1 composed of three radial pentayne groups linked to a central benzene moiety by alkyl spacers.
Figure 2 Structure model of the nematic columnar(NCol) bulk mesophase formed by the star‐shaped pentayne oligomer 1.
Figure 3 Schlieren texture of a spin‐coated pentayne 1 film on glass substrate between crossed polarizers after thermal treatment within the mesophase and cooling down to room temperature.
Figure 4 Optical textures of spin‐coated films of the star‐shaped oligomesogen 1 on polyimide alignment layers at room temperature after annealing within the mesophase; a) Polyimide SE‐3140. The disclination lines run predominantly parallel to the rubbing direction of the orientation layer; b) Polyimide ZLI‐2650; c) after rotation of the sample in b) by 45° arround the optical axis.
Figure 5 (x) Retardation of a 1.1 µm thick film of compound 1 depending on the incidence angle after thermal treatment on ZLI‐2650 polyimide layer. (+) is a fit of a negatively uniaxial tilted model to the data. The values for incidence angles from 35°–50° were determined at a azimuth differing by 6° from the linear eigenpolarisation and were excluded from the fitting procedure.
Figure 6 Schematic presentation of possible molecular orientations of the discotic pentayne cores of the star‐shaped oligomesogen 1 after annealing on top of a rubbed polyimide layer; a) Alignment with a uniform tilt angle; b) Splayed orientation with continuous alteration of the tilt angle. The macroscopic orientation is frozen in a glassy state at room temperature.
Figure 7 Polarized emission spectra of an aligned film of the pentayne star oligomer1 on polyimide ZLI‐2650 by excitation with non‐polarized 360nm‐light. The polarizer was oriented perpendicular (straight line) and parallel (dotted line) to the director of the orientation layer.
