Liquid crystalline blue phase I observed for a bent-core molecule and its electro-optical performance

Effects of 1,3,4-oxadiazoles with different rigid cores on the thermal and electro-optical performances of liquid crystalline blue phases

“…In addition, both the rise time and the decay time of all samples were less than 1 ms. Unfortunately, BPI disappeared after several switching circles, and could never reverse again, which may result from the low miscibility or decomposition of the oxadiazole derivatives [34]. Therefore, in order to overcome these problems, we are trying to synthesise biaxial LC molecules with relatively high miscibility, good stability, large intrinsic birefringence and low phase-transition temperature.…”

“…A chiral dopant, R811 (Merck) or Iso-(6OBA) 2 (synthesised by our laboratory), the same as that used by Lee et al [34], was used to induce BPs or a chiral nematic phase (N * ). The monomers used in this study to form a polymer network in the composites were tri-functional monomer Trimethylolpropane Triacrylate (TMPTA, Aldrich) and di-functional monomer C6M (Merck); the photoinitiator was Irgacure 651 (Aldrich).…”

“…Interestingly, 2,5-disubstituted 1,3,4-oxadiazoles are prone to form the banana-shaped molecules and are suitable for the formation of the biaxial nematic phase due to their large bend angle (∼134 • ) [29][30][31][32][33]. When doped with a high twisted power chiral dopant, Lee et al [34] observed more than 15 • C range of BPI for a biaxial 1,3,4-oxadiazole molecule. Moreover, Zheng et al [35,36] and Wang et al [37] reported that wide BPs could be induced by doping 1,3,4-oxadiazole derivatives with different lengths of the terminal chain into 630 L. Wang et al N * LC, and the effects of the terminal chain length on the BP ranges had been also explored.…”

Effect of bent-shape and calamitic-shape of hydrogen-bonded mesogens on the liquid crystalline properties

“…[9][10][11] Additionally, it has been theoretically predicted that the bent-shape compounds with biaxiality may play an important role in stabilising the blue phase (BP) due to the molecular biaxiality relieving some of the frustration of the defect lines. [12] In order to design LC materials exhibiting the desired mesophase behaviour and excellent performance in fast light modulators or tunable photonic crystals, many bent-shape compounds such as 1,3-disubstituted benzene, [13] 1,2-disubstituted benzene, [14] 2,5-disubstituted 1,3,4-oxadiazole [15,16] and 2,7-disubstituted naphthalene [17] have been previously investigated by either blending them with chiral dopants or doping them into the chiral nematic liquid crystal (N*LC). Up to now, at least seven phases of banana-shape LCs have been described and these phases are not comparable with smectic phases formed by calamitic mesogens.…”

Liquid Crystals for Responsible Photonic Crystals

“…The ability to dynamically tune the photonic bandgap in cubic BPs across a wide wavelength range is highly desirable. Effort to improve the instability and irreversibility of BPs has been made with polymer-stabilized structure [18] and incorporation of unusual bent-core mesogen [42]. …”