Photoalignment of Chromonic LC-Silica Nanohybrid

Among vast varieties of lyotropic LCs, chromonic mesophases are the families of new research target starting only about two or three decades ago. The properties are different from those of ordinary lyotropic mesogens of surfactant type. The molecules constitute aromatic(s) in the center, and hydrophilic parts are scattered around the molecules rather than aliphatic structures. Therefore, they are rigid and planar disklike or planklike, rather than micelles of flexible molecular assemblies of ordinary surfactants. The molecules aggregate in solution to form 

Nanohybridization of B67 with silica network was recently attempted by Hara et al. (2007). The chromonic LC of B67 was mixed with silica precursor of tetraethoxysilane (TEOS) together with an anionic surfactant (EmalC20) and 2-(2-aminoethoxyl)ethanol (AEE). Here AEE plays an important role in stabilizing the columnar structure of B67. This molecule works as the mediator of the interface between the anionic B67 aggregate and silica. Without AEE, the columnar structure is transformed to a lamella structure in the process of drying (Hara et al., 2007). 

The optical anisotropy of the nanohybrid films obviously obeys the direction of the preirradiated LPL to the photocrosslinkable polymer liquid crystal (PPLQ film, and the effect of flow orientation because the lifting from the sol solution is 

---

Figure 8.5, Photoalignment of chromonic LC/silica nanohybrid. Chemical struc-ture of the component and a scheme of B67 columns on a photoaligned PPLC film. See color insert.

---