Polymer-sustained-alignment liquid crystal cell produced from the monomer containing benzilketal-group and its image sticking property

• Published in: Liquid crystals 2021-01, Vol.48 (1), p.35-42
• Main Authors: Mizusaki, Masanobu, Enomoto, Satoshi, Hara, Yuki
• Format: Article
• Language: English
• Subjects: Alignment; benzylketal; Direct current; Electric potential; Enlargement; image sticking; Liquid crystal displays; mixed monomers; Monomers; Polymer layer; Polymerization; Polymers; self-cleavage reaction; Voltage
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2020.1762131

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the polymer layers produced from mixed monomers of 4,4ʹ-dimethacryloyl-oxy-biphenyl (4,4ʹ-DMABiph) and 4,4ʹ-dimethacryloyl-oxy-benzilketal (4,4ʹ-DMABzk) were fabricated and investigated image sticking phenomenon with evaluations of residual direct current voltage (V rDC ) and difference in pretilt angle before and after application of alternate current voltage (∆tilt). A rate constant of the polymerisation became remarkably large with an addition of a small amount of 4,4ʹ-DMABzk into 4,4ʹ-DMABiph. The V rDC was effectively improved with the addition of a small amount of 4,4ʹ-DMABzk because the concentrations of radicals and/or ions in the LC layer were decreased due to enlargement for the rate constant of the polymerisation. The Δtilt was small enough only below 10% of 4,4ʹ-DMABzk in the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk. We confirmed that the PSA-LC cell produced from the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk with the weight ratio of 4,4ʹ-DMABzk between 6% and 10% was useful for obtaining the small level of image sticking.