Stable amorphous blue phase of bent-core nematic liquid crystals doped with a chiral material

Taushanoff, Stefanie; Le, Khoa V.; Williams, Jarrod; Twieg, Robert J.; Sadashiva, B. K.; Takezoe, Hideo; Jákli, Antal

doi:10.1039/c0jm00690d

Cited by 116 publications

(93 citation statements)

References 30 publications

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“…• C Polarized microscope images at different temperatures show dark images at T = 35.9 • C. As temperature decreases, the uniform dark texture becomes gradually brighter, as Taushanoff et al also observed in their BPIII system [32]. When the temperature is lowered below T = 34.8 • C, oily streaks which are a typical defect line for the cholesteric phase appears.…”

Section: 0mentioning

confidence: 78%

Nonlinear Rheology and Fracture of Disclination Network in Cholesteric Blue Phase III

Fujii

Sasaki

Orihara

2018

Fluids

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Nonlinear rheological properties of chiral crystal cholesteryl oleyl carbonate (COC) in blue phase III (BPIII) were investigated under different shear deformations: large amplitude oscillatory shear, step shear deformation, and continuous shear flow. Rheology of the liquid crystal is significantly affected by structural rearrangement of defects under shear flow. One of the examples on the defect-mediated rheology is the blue phase rheology. Blue phase is characterized by three dimensional network structure of the disclination lines. It has been numerically studied that the rheological behavior of the blue phase is dominated by destruction and creation of the disclination networks. In this study, we find that the nonlinear viscoelasticity of BPIII is characterized by the fracture of the disclination networks. Depending on the degree of the fracture, the nonlinear viscoelasticity is divided into two regimes; the weak nonlinear regime where the disclination network locally fractures but still shows elastic response, and the strong nonlinear regime where the shear deformation breaks up the networks, which results in a loss of the elasticity. Continuous shear deformation reveals that a series of the fracture process delays with shear rate. The shear rate dependence suggests that force balance between the elastic force acting on the disclination lines and the viscous force determines the fracture behavior.

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Section: 0mentioning

confidence: 78%

Nonlinear Rheology and Fracture of Disclination Network in Cholesteric Blue Phase III

Fujii

Sasaki

Orihara

2018

Fluids

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“…2b in Ref. [11]). Hence this unknown texture is attributed to the coexistence of N * and BPIII and the subpeaks in the inset of Fig.…”

Section: Methodsmentioning

confidence: 90%

Blue Phase III—Isotropic Phase Transition in a Bent-Core Liquid Crystal with Chiral Dopant

Aihara

Isobe

et al. 2012

Ferroelectrics

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Calorimetric measurements and optical observations have been performed to investigate the effect of chirality on a bent-core nematic (BCN) material which can exhibit an amorphous blue phase (BPIII) over a wide temperature range by mixing with a highly chiral dopant. It was found that the first-order character of the nematic (N)-isotropic (I) phase transition of the host BCN sample was clearly weakened by increasing the chiral dopant concentration and eventually moved into the supercritical evolution. The colors of the textures also showed a blue shift when increasing the chiral concentration.

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“…Achiral bent-core dopants were also used for BP stabilization as polymers and nanoparticles did [213], and the phase temperature range was greatly widened. Jeong et al [214] reported that UV irradiation of an azo-benzene bent-core LC doped with chiral molecules leads to a photo-induced transition from BPI to BPIII, accompanied by BPIII stabilization of 20 • C. Many papers dealing with BPs and bent-core molecules have been published [215][216][217][218][219]. How to achieve uniform alignment might be still an important issue to consider for bent-core BP viable applications.…”

Section: Othersmentioning

confidence: 99%

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

Zhang¹

2013

Intelligent Stimuli‐Responsive Materials

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The three classic states of matter are well known and ubiquitous in everyday life: solid, liquid, and gas. Liquid crystals (LCs), an intermediate state between solid crystal and isotropic liquid, constitute a new fascinating class of condensed soft matter uniquely combining both fluidity and long-range order. The fluid-like mobility enables LCs to be switchable under external stimuli, and crystal-like long-range order bestows anisotropic physical properties on LCs. LCs can be divided into two main classes: thermotropic and lyotropic. Thermotropic LCs consist of individual molecules (or ion pairs) and exhibit phase transitions with the change of temperature. In this case, temperature is the fundamental thermodynamic factor determining mesophase formation. Lyotropic LCs are a special type of solution system that can form mesophases as a function of both temperature and concentration of LC molecules. The building block of a lyotropic phase is an aggregate (called a micelle) formed via self-assembly of many molecules (typically on the order of 100). Examples of LCs can be found both in the natural world and in technological applications. Thermotropic LCs find 189 190 ELECTRIC-AND LIGHT-RESPONSIVE BENT-CORE LIQUID CRYSTALS a wide variety of uses in displays, and an important example of lyotropic LCs is cell membranes formed by amphiphilic lipids. Surfactants in water (i.e., soap water) constitute another useful example of lyotropic LCs. Although the majority of LCs are organic molecules, there exist many LC materials incorporating metals into organic anisotropic molecules [1-3]. These organic-inorganic hybrid LC materials are described as metallomesogens and are recently called metallotropic LCs [4] as distinguished from two main LC classes. In fact, metallomesogens can be classified as either thermotropic or lyotropic LCs depending on their composition and conditions. However, it should be noted that metallomesogens offer a material platform to incorporate magnetic, electronic, optical, redox, and catalytic properties common to inorganic materials into LCs.Although thermotropic LCs have been known to scientists for over 100 years since a discovery by the Austrian botanical physiologist Friedrich Reintizer in 1888, it was only in the late 1960s that they began to be used in display applications. Today, they are best known for their exceptionally successful commercial applications in flat panel display products such as TVs, smart phones, computer displays, and digital projectors. Although today's LC display technology is becoming very advanced, LC materials used in display devices possess the simplest nematic (N) phase and their molecules have been variants on simple rod shapes (Fig. 6.1a). Besides nematic phases, LCs can exhibit other phases: smectic (Sm), columnar (Col), and cubic phases, depending on the orientational or positional orders of their molecules. Nematic phases have only long-range orientational order, smectic mesophases exhibit one-dimensional (1D) positional order and form two-dimensional (2D) layered ...

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Stable amorphous blue phase of bent-core nematic liquid crystals doped with a chiral material

Cited by 116 publications

References 30 publications

Nonlinear Rheology and Fracture of Disclination Network in Cholesteric Blue Phase III

Nonlinear Rheology and Fracture of Disclination Network in Cholesteric Blue Phase III

Blue Phase III—Isotropic Phase Transition in a Bent-Core Liquid Crystal with Chiral Dopant

Electric‐ and Light‐Responsive Bent‐Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications

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