Liquid crystal (LC) alignment layer is one of the key materials of liquid crystal display (LCD). At present
the effect of polyimide (PI) structure on LC pretilt angle has been investigated widely
but the study on effect of additive on the pretilt angle was less. In this paper
pyromellitic dianhydride (PMDA)
1
2
3
4-cyclobutanetetracarboxylic dianhydride (CBDA)
4 benzeneamine
4-hexyloxy-biphenyl-3'
5'-diaminobenzoate
and additive ADD-34 were used to synthesize four PIs. The uniform LC molecule alignment induced by PI alignment films was confirmed by polarized optical microscope. It was found that the PI with ADD-34 possesses solvent resistance. LC pretilt angle increased firstly and then decreased with the increase of ADD-34 content in PI.
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references
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