From a Chiral Molecule to a Chiral Anisotropic Phase

Kuball, Hans‐Georg; Höfer, Tatiana

doi:10.1007/0-387-21642-1_3

Cited by 29 publications

(14 citation statements)

References 66 publications

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“…Of special interest are those blending ratios where the pitch has a value on the order of the wavelength of visible light. In this case, the chiral nematic LCs have the ability to reflect circularly polarized light of the same handedness 15 as that of the molecular helix and with a reflection wavelength λ that scales with the pitch p through the in-plane average index n ̅ : λ = n ̅ p. An example of a monomer blend and its corresponding pitch and reflection wavelength is shown in Figure 6. The bandwidth of the reflection band scales with the birefringence of the monomer by Δλ = Δnp.…”

Section: ■ Liquid Crystal Monomersmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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Monolithically ordered liquid crystal polymer networks are formed by the photoinitiated polymerization of multifunctional liquid crystal monomers. This paper describes the relevant principles and methods, the basic structure− property relationships in terms of mesogenic properties of the monomers, and the mechanical and optical properties of the polymers. Strategies are discussed to control the molecular orientation by various means and in all three dimensions. The versatility of the process is demonstrated by two examples of films with a patterned molecular order. It is shown that patterned retarders can be made by a two-step polymerization process which is successfully employed in a transflective display principle. A transflective display is a liquid crystal display that operates in both a reflective mode using ambient light and a transmissive mode with light coming from a backlight system. Furthermore, a method is discussed to create a patterned film in a single polymerization process. This film has alternating planar chiral nematic areas next to perpendicularly oriented (so-called homeotropic) areas. When applied as a coating to a substrate, the film changes its surface texture. During exposure to UV light, it switches from a flat to a corrugated state.

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Section: ■ Liquid Crystal Monomersmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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“…A notable exception is the lack of a general theory for the prediction of how strongly the presence of chiral centers in molecules affects phase behavior and structure on mesoscopic length scales [1]. Even when the molecular shape is symmetric and very well known, such as the double helical shape of B-DNA, the cooperative effects of the molecular chirality are amazingly complex and hard to model [2][3][4][5].…”

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confidence: 99%

Propagation of Chirality in Mixtures of Natural and Enantiomeric DNA Oligomers

et al. 2013

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“…The designation of left and right handedness is done via the set of rules provided by Cahn, Ingold and Prelog (CIP-system) [13]. A measure of chirality on the other hand is not trivial to define [14]. Normally, only quantities which allow a comparison between two chiral objects (molecules) are presented, such as optical activity, circular dichroism (CD) or optical rotation dispersion (ORD).…”

Section: Chiralitymentioning

confidence: 99%

Chiral Liquid Crystals: Structures, Phases, Effects

2014

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The introduction of chirality, i.e., the lack of mirror symmetry, has a profound effect on liquid crystals, not only on the molecular scale but also on the supermolecular scale and phase. I review these effects, which are related to the formation of supermolecular helicity, the occurrence of novel thermodynamic phases, as well as electro-optic effects which can only be observed in chiral liquid crystalline materials. In particular, I will discuss the formation of helical superstructures in cholesteric, Twist Grain Boundary and ferroelectric phases. As examples for the occurrence of novel phases the Blue Phases and Twist Grain Boundary phases are introduced. Chirality related effects are demonstrated through the occurrence of ferroelectricity in both thermotropic as well as lyotropic liquid crystals. Lack of mirror symmetry is also discussed briefly for some biopolymers such as cellulose and DNA, together with its influence on liquid crystalline behavior.

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From a Chiral Molecule to a Chiral Anisotropic Phase

Cited by 29 publications

References 66 publications

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Propagation of Chirality in Mixtures of Natural and Enantiomeric DNA Oligomers

Chiral Liquid Crystals: Structures, Phases, Effects

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