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

Abstract

2012) Effects of 1,3,4-oxadiazoles with different rigid cores on the thermal and electro-optical performances of liquid crystalline blue phases, Liquid Crystals, 39:5, 629-638, A series of symmetrically 2,5-disubstituted 1,3,4-oxadiazoles with different rigid cores were synthesised under the microwave irradiation based on green chemistry and atom economy. The induced blue phase (BP) behaviours of these bent-shaped compounds were investigated after blending them with a high twisted power chiral dopant or doping them into the chiral nematic liquid crystal (N * LC). It was found that the BP ranges varied greatly with the difference in the rigid cores of 2,5-disubstituted 1,3,4-oxadiazoles, and the bent-shaped molecules with higher miscibility and twisted molecular conformation significantly contribute to the stabilisation of BPs. In addition, the electro-optical performances of pure BPs and polymer-stabilised BPs in the systems containing 1,3,4-oxadiazoles with different rigid cores were also explored, which shows that the Kerr constant decreases after being polymerised and varies with the doping of the compounds possessing different rigid cores in the polymerised mixtures.

Self-activating liquid crystal devices for smart laser protection

“…It has been experimentally and theoretically confirmed that the BP II and BP I exhibit simple cubic and body-centered cubic nanostructures (Figure 8(a)), respectively. Due to the unique 3D structures of BPLCs, they exhibit many revolutionary features such as optically isotropic and alignment-layer-free, while possess superior electrooptic properties and non-linear optical responses comparable to nematics [134][135][136][137][138][139][140][141][142][143][144][145][146][147][148]. Furthermore, because of the tightly wound spatial arrangement of the crystalline axis, the scattering loss due to thermal fluctuations of the director axis is considerably smaller than nematics, allowing longer interaction length and higher process efficiency.…”

Nature‐Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self‐Assembly to DNA Mesophase and Nanocolloids

“…To stabilize BPs over a wide temperature range, various promising strategies have been proposed including new molecular design, polymer stabilization, doping functional nanoparticles, etc. [297][298][299][300][301][302][303][304][305][306][307][308][309][310][311][312][313][314][315][316] Among them, polymer stabilization enables the formation of BPs with a wide temperature range over 60 K down to room temperature, which are very attractive for next-generation ultrafast display due to numerous advantageous properties such as sub-millisecond response time and wide viewing angle. [317][318][319][320] Interestingly, BPs have been widely investigated for photonic applications in areas of lenses, gratings, lasers, spatial phase modulators, and so on.…”

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.…”