Free surface command layers for the photoalignment

ABSTRACT

The photoaglinment technologies of liquid crystalline (LC) materials are becoming more important in industries for the fabrication of LC display panels. The photoalignment is based on the anisotropic photoreaction taking place on the substrate surface. We recently proposed a new strategy of surface alignment of LC polymer films utilizing the free (air side) surface instead of solid substrate surface. This short review describes our recent advances of such approach using azobenzene- and cyanobiphenyl- containing side chain liquid crystalline polymers, focusing on the important role of the free surface to control the side chain mesogen orientation. Three series of results are introduced here: i) the first motivation to demonstrate the effect of free surface layer, ii) the alternation of orientation by the rigidity of main chain structure, which is governed by the free surface, and iii) the out-of-plane photocontrol of mesogens by the photoresponsive skin layer at the free surface.

KEYWORDS:

• Azobenzene
• command layer
• free surface
• inkjet printing
• mesogen orientation
• photoalignment

Funding

This work was supported by JSPS KAKENHI under Grant Numbers JP15H01084 in Scientific Research on Innovative Areas “Photosynergetics,” and by JSPS KAKENHI under JP16H01084, JP 15K13784 in Scientific Basic Research.