Liquid crystal alignment behavior on sulfonated poly(arylene ether sulfone) films

Abstract

A series of sulfonated poly(arylene ether sulfone) (PAES#, # is the feed monomer ratio of 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone) derivatives were synthesized via nucleophilic addition to investigate the liquid crystal (LC) alignment property of these polymer films. These polymer films exhibited good optical transparency in the visible light region (400–700 nm). For example, the transmittance value (about 96%) of the PAES# film onto a glass substrate at 550 nm is better than that (about 90%) of the polyimide film, the most commonly used LC alignment layer. The LC cells made from the rubbed PAES# films showed a homogeneous planar LC alignment with parallel direction with respect to the rubbing direction. LC cells having pretilt angles from approximately 3° for twisted nematic (TN) to 0° for planar switching mode were obtained from these PAES# films having molar contents of sulfonate groups in the range of 0 to 70 mol%, respectively. The electro-optical characteristics of the LC cells fabricated with the PAES# films such as applying voltage and response time were as good as those fabricated from rubbed polyimide films. We also found that the LC cells made from PAES# films exhibited good thermal stability.