Flow behaviours of liquid crystals on vertical alignment layers of polyimides
Nematic liquid crystals (LCs) dropped via micro-dispenser (3 μL) on a vertical alignment (VA) polyimide coated indium tin oxide glass substrate have been observed under crossed polarisers. The wettability between the LC and the VA polyimide layer was extremely low. The contact angle
of the LC droplet was around 33° and the droplet diameter was much smaller than the LC on the parallel-aligned polyimide layer. The contact angle of the droplet increased, and the droplet diameter decreased, on increasing the molar fraction of the side group of the polyimide. The flow
behaviour of the LC by assembling between the two substrates has been directly observed under crossed polarisers. The droplet spread out keeping a cross-extinction pattern during assembling. After assembling to a 5 μm gap, a dark field was observed in whole area on the polyimide alignment
layer with 50 mol% side group. Increasing the side group enhanced aligning the LC perpendicular to the substrate, and no disclination appeared.
Keywords: ODF; alignment layer; droplet; liquid crystal; polyimide; side group
Document Type: Research Article
Affiliations: 1: Yamagata University, Yonezawa-shiYamagata, Japan 2: Hitachi Plant Technologies Ltd, RyugasakiIbaragi, Japan
Publication date: 01 September 2011
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