Stability of Photoaligning Materials Sensitivity to UV Light

The stability of LC photoaligning materials was a major concern from the very beginning of their development as LC aligning agents [1], The stable photoaligning materials with respect to UV and IR radiation are photosensitive Pis or crosslink-able materials (see Chapter 2). 

SDAl was dissolved in dimethylformamide (DMF) and doped with 0.02% of a thermal polymerization initiator V-65 (from Wako Pure Chemicals Industries, Ltd.). The mixture was spin coated onto glass substrates and photoaligned in the same manner as SDl. After the photoalignment, the SDAl film was heated at 150 °C for 1 h for the purpose of thermal polymerization. LC on the SDAl 

The presence of foreign molecules inside the azo-dye film can greatly affect the ease of rotational diffusion during the photoaligning process [43]. In particular. 

5 Comparison of the Characteristics of Photoalignment Layers for Different Mechanisms of LC Photoalignment 

As follows from Table 3.1, pure reorientation (diffusion) is the most suitable mechanism for LC photoalignment. The commercialization of the materials produced by the Die Corporation (Japan) is expected soon [45, 46]. The first target should be the photoaligning of monomers and LC polymers for phase retarder applications (Chapter 5). Photoaligning with azo-dye layers will be considered below. 

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