Water-soluble aromatic polyamide as a low-temperature-processable alignment layer: Poly(2,2 '-disulfo-4,4 '-benzidine isophthalamide) cesium salt

Abstract

A water-soluble aromatic polyamide (WAPA) thin film was formed by coating a newly synthesized poly(2,2'disulfo-4,4'-benzidine isophthalamide) cesium salt (PDBI-Cs). Its electro-optical properties as an alignment layer in liquid crystal devices were analyzed. Twisted nematic-liquid crystal cells containing WAPA alignment layers annealed at a low temperature of 100 degrees C showed high voltage holding ratio values above 95 % at a frame rate of 60 Hz, a fast response time of 7.18 ms at ac operation of 1 kHz under LC-applied voltage of 5 V, and excellent contrast ratio of 3284 due to the high optical anisotropy effect of the WAPA surface. Thus, PDBI-Cs-based WAPA can be a promising candidate as a new eco-friendly low-temperature-processable alignment layer for flexible electro-optic devices.