We synthesized polythiophene (PTh) derivatives having a methyl group at 4-position and a mesogenic group, or an ionic group at
3-position in the thiophene ring via a flexible spacer by oxidative polymerization with FeCl3 and investigated regioregularity, thermal, electrical and optical properties of the PTh derivatives. The regioregularity of the PTh derivatives with a mesogenic group was over 90%. A smectic phase was observed for two PTh derivatives with mesogenic group. The electrical conductivity was about 10-3~10-4 Scm-1for the PTh derivatives doped with I2 vapor in the film state. PTh derivatives containing methylimidazolium salt derivative at the
3-position of thiophene ring were soluble in water. To investigate ionochromism of the aqueous solution of PTh derivatives containing
methylimidazolium salt derivative, some salts were added to the aqueous solution. The absorption peak based upon the π conjugation of the polymer backbone was shifted to the longer wavelength region, when NaI, KI or LiI salts were added to the aqueous solution of the PTh derivatives. This ionochromism behavior of the aqueous solution of PTh derivatives containing methylimidazolium salt derivative would be applied to the chemosensor.
We synthesized two side chain polymethacrylate derivatives polymers 1 and 2 side chain polymer 3 and 4 and main chain polyimide polymer 5 derivatives containing a chalconyl moiety to investigate the extent of photoreaction and photoalignment behavior of liquid crystalline (LC) molecules. A smectic A phase was exhibited for the polymethacrylate derivatives, while polyimide derivatives did not show any mesophases. Only a glass transition was observed for the polyimides. The LC phase of polymethacrylate derivatives showed a good value of the extent of photoreaction, while the extent of photoreaction for polyimides above glass transition temperature was also larger than that below glass transition temperature. Mixtures of low molar mass liquid crystal (MBBA or 5CB) and dichroic dye were filled in the LC cell fabricated from the polymer. In the case of the LC cells fabricated from polymer 1 film irradiated with linearly polarized UV (LPUV) light in the LC phase, the dichroic ratio (DR) values were positive showing parallel orientation of the LC molecule to the electric vector of the incident LPUV light. The DR values were also positive for the LC cells fabricated from the polymers 3 and 4 film irradiated with LPUV light, while the negative DR values were obtained for the polymer 5 film.