Preparation and characterization of novel polyimide with chiral side chain for twist nematic liquid crystal display

Abstract

The synthesis of novel polyimide (PI) films containing chirals in side chain was investigated for utilizing in twist nematic (TN) liquid crystal display (LCD). The polyimide with amine side groups (PI4 a.m.) was prepared by two steps copolymerization of 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), 4,4′-oxydianiline (ODA), and 3,3′-diaminobezidine (4 a.m.) in N-methyl-2- pyrrolidinone (NMP). In the first step, the oligomer of 6FDA and ODA with mole ratio 4 : 3 was synthesized. In the second step, the oligomer was reacted with 4 a.m. by gradually dropping the oligomer into 4 a.m. solution with the mole ratio 4 : 5. By reacting chiral compounds, mandelic acid, menthyl chloroformate, and menthyl glyoxylate hydrate using condensation reaction with amine groups along polyimide molecules, the novel polyimides can be synthesized. Their chemical structures were confirmed by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H-NMR). The coated glass slides pairs were coated with PI4 a.m. and with each Polyimide/chiral. The liquid crystals (LCs) were inserted between two coated glass slides at above the nematic temperature under the polarized light microscope to observe the alignment of LCs. The results showed the alignment of LCs in some certain direction under Polyimide/chiral pair, regardless of the type of the chiral molecule. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011