Field‐Induced Switching of the Layer Chirality in SmCP Phases of Novel Achiral Bent‐Core Liquid Crystals and their Unusual Large Increase in Clearing Temperature under Electric Field Application

Schröder, Martin; Diele, Siegmar; Pelzl, G.; Weißflog, W.

doi:10.1002/cphc.200300904

Cited by 76 publications

(43 citation statements)

References 23 publications

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“…Rotation around the long axis reverses the chirality, while rotation around the cone preserves the chirality of the layer fragments. [16,17] Both types of switching, which preserve or reverse the chirality, have also been observed in the lamellar smCP A (B2) phase. [10,17] However, in the case of columnar phases with an oblique unit cell, the switched-on (ferroelectric) state is always structurally chiral, independently of the switching mechanism.…”

Section: Resultsmentioning

confidence: 92%

Switching Mechanism in Polar Columnar Mesophases Made of Bent‐Core Molecules

et al. 2005

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The behaviour of polar, broken-layer-type columnar phases made of bent molecules (B(1Rev) and B(1RevTilted)) was studied under an applied electric field. There are two competing mechanisms of ferroelectric switching in the polar B(1RevTilted) columnar phase: collective rotation around the long molecular axis and collective rotation around the tilt cone. The proposed model shows that the main factor discriminating the type of switching is the width of the column cross-section.

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Section: Resultsmentioning

confidence: 92%

Switching Mechanism in Polar Columnar Mesophases Made of Bent‐Core Molecules

et al. 2005

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“…[103][104][105] Lately, the orthoconic effect has also been found in several other materials (some of them are depicted in Table 3), quite different from the initially used mixture (which will be discussed in more detail below): in bent-core mesogens, [106,107] in a bistereogenic AFLC (M7BBM7) structurally related to MHTAC, [90] in a "twin AFLC mesogen" compound (BMHBOP-8), [88] and recently also in a siloxane bimesogen (Br11-3-11Br). [94] Siloxane bimesogens are actually some of the best-studied, high-tilt AFLCs, which have been investigated repeatedly since 1997.…”

Section: Solution Of the Static Dark-state Problem In Antiferroelectrmentioning

confidence: 99%

“…[88] An improved alignment could be achieved with both these types of bimesogenic compound by electric-field treatment and/or slow cooling into the smectic phase [88,93] (see the BMHBOP-8 example in Figure 22), but such alignment methods are not realistic in commercial display production. Some orthoconic AFLCs belonging to the class of bent-core mesogens have been identified, [106,107] but they do not align well and the mesophase temperature ranges are also generally far too high. Thus, it seems that materials similar to W107, with SmA* in the phase sequence and exhibiting a tilting transition with strong de Vries component, are the most promising.…”

Section: Aflc Materials Exhibiting High Director Tiltmentioning

confidence: 99%

Current Topics in Smectic Liquid Crystal Research

2006

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Interest in the smectic liquid-crystalline state of matter received a substantial boost with the discovery by Meyer in the mid-1970s that a chiral smectic C (SmC*) phase exhibits a spontaneous electric polarization, and with the subsequent demonstration by Clark and Lagerwall of the surface-stabilized SmC* ferroelectric liquid crystal at the beginning of the 1980s. Since then, chiral smectic phases and their plethora of polar effects have dominated the research in this field, which today has reached a mature state where the first commercial microdisplay applications are now shipping in millions-per-year quantities. In this Review we discuss some of the topics of highest interest in current smectic liquid crystal research, and address application-relevant research (de Vries-type tilting transitions without defect generation and high-tilt antiferroelectric liquid crystals with perfect dark state) as well as more curiosity-driven research (the nature and origin of the chiral smectic C subphases and their intermediate frustrated states between ferro- and antiferroelectricity).

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“…Nakata et al [8] and Bedel et al [9] were able to detect this switching mechanism above a critical electric field. Schröder et al [7] observed this kind of polar switching only on very slow increase or decrease of the electric field. It should be emphasized that the field-induced switching in tilted "banana phases" by rotation around the long axes is accompanied by an inversion of the layer chirality.…”

mentioning

confidence: 93%

“…In polar smectic A (SmAP) phases [4,5] and in B 1rev phases formed by SmAP-like layer fragments [6] this mechanism is the only possibility for polar switching. There are a few examples that this switching mechanism can also occur in tilted SmCP A phases [7][8][9] as well as in B 1rev phases with SmCP-like layer fragments, [6] mostly under special experimental conditions. Nakata et al [8] and Bedel et al [9] were able to detect this switching mechanism above a critical electric field.…”

mentioning

confidence: 99%