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47 results on '"Nakata, Michi"'

1. Twist-bend heliconical chiral nematic liquid crystal phase of an achiral rigid bent-core mesogen

Author

Chen, Dong, Nakata, Michi, Shao, Renfan, Tuchband, Michael R., Shuai, Min, Baumeister, Ute, Weissflog, Wolfgang, Walba, David M., Glaser, Matthew A., Maclennan, Joseph E., and Clark, Noel A.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

The chiral, heliconical (twist-bend) nematic ground state is reported in an achiral, rigid, bent-core mesogen (UD68). Similar to the nematic twist-bend (NTB) phase observed in bent molecular dimers, the NTB phase of UD68 forms macroscopic, smectic-like focal-conic textures and exhibits nanoscale, periodic modulation with no associated modulation of the electron density, i.e., without a detectable lamellar x-ray reflection peak. The NTB helical pitch is pTB ~ 14 nm. When an electric field is applied normal to the helix axis, a weak electroclinic effect is observed, revealing 50 um-scale left- and right-handed domains in a chiral conglomerate., Comment: 19 pages, 4 figures

Published
2013
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5. Chiral memory on tradition between the B2 and B4 phases in an achiral banana-shaped molecular system

Author

Niwano, Hiroko, Nakata, Michi, Thisayukta, Jirakorn, Link, Darren R., Takezoe, Hideo, and Watanabe, Junji

Subjects
Circular dichroism -- Research, Chirality -- Analysis, Chemicals, plastics and rubber industries
Abstract

The correlation between chirality of the B2 and B4 phases are examined by measuring the circular dichroism in the classic bent-core molecule. By incorporating the optical microscopic observations with the CD measurements, it is found that once the chiral domains are formed in the B4 phase they are conserved thereafter on successive transformation between the B2 and B4 phases.

Published
2004

6. Physical polymerization and liquid crystallization of RNA oligomers

Author

Zanchetta, Giuliano, Bellini, Tommaso, Nakata, Michi, and Clark, Noel A.

Subjects
Chirality -- Analysis, Polymerization -- Analysis, RNA -- Structure, RNA -- Chemical properties, Chemistry
Abstract

NanoRNA has displayed self-assembly into chiral nematic (N*) and higher concentration, columnar (COL) phases, which has shown that this form of spontaneous ordering is universal in nucleic acids (NAs). The studies have established the connection between the supramolecular organization of RNA oligomers and their degree of complimentarity.

Published
2008

7. Reflection symmetry breaking in achiral rod-shaped smectic liquid crystals?

Author

Walba, David M., Korblova, Eva, Cheng-Cher Huang, Shao, Renfan, Nakata, Michi, and Clark, Noel A.

Subjects
Liquid crystals -- Structure, Liquid crystals -- Chemical properties, Benzene -- Chemical properties, Chemistry
Abstract

The results of an investigation, which shows that the chirality of SmC phase derives from surface interactions, are described. No evidence for the presence of a ferroelectric polarization in the SmC phase of 4'-octyloxyphenyl-4-octyloxybenzoate, a necessary result of chiral symmetry of the phase, could be found, even though very sensitive tests for such polarization are applied.

Published
2006

9. A Modulated Helical Nanofilament Phase

Author

Tsai, Ethan, primary, Richardson, Jacqueline M., additional, Korblova, Eva, additional, Nakata, Michi, additional, Chen, Dong, additional, Shen, Yongqiang, additional, Shao, Renfan, additional, Clark, Noel A., additional, and Walba, David M., additional

Published
2013
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12. Structure of the B4 Liquid Crystal Phase near a Glass Surface

Author

Chen, Dong, primary, Heberling, Michael-Scott, additional, Nakata, Michi, additional, Hough, Loren E., additional, Maclennan, Joseph E., additional, Glaser, Matthew A., additional, Korblova, Eva, additional, Walba, David M., additional, Watanabe, Junji, additional, and Clark, Noel A., additional

Published
2011
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13. Houghet al.Reply

Author

Hough, Loren E., primary, Zhu, Chenhui, additional, Nakata, Michi, additional, Chattham, Nattaporn, additional, Dantlgraber, Gert, additional, Tschierske, Carsten, additional, and Clark, Noel A., additional

Published
2008
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17. Chiral SmA∗ materials for display applications?

Author

Walba, David M., primary, Korblova, Eva, additional, Eshdat, Lior, additional, Biewer, Michael C., additional, Yang, Hong, additional, Jones, Christopher, additional, Nakata, Michi, additional, Talarico, Mara, additional, Shao, Renfan, additional, and Clark, Noel A., additional

Published
2007
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21. Electric-field-induced transition between the polarization-modulated and ferroelectric smectic-CSPF*liquid crystalline states studied using microbeam x-ray diffraction

Author

Nakata, Michi, primary, Link, Darren R., additional, Takanishi, Yoichi, additional, Takahasi, Yumiko, additional, Thisayukta, Jirakorn, additional, Niwano, Hiroko, additional, Coleman, David A., additional, Watanabe, Junji, additional, Iida, Atsuo, additional, Clark, Noel A., additional, and Takezoe, Hideo, additional

Published
2005
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41. Main-Chain Chiral Smectic Polymers Showing a Large Electroclinic Effect in the SmA Phase

Author

M. Walba, David, Yang, Hong, K. Shoemaker, Richard, Keller, Patrick, Shao, Renfan, A. Coleman, David, D. Jones, Christopher, Nakata, Michi, and A. Clark, Noel

Abstract

The synthesis and characterization of a main-chain smectic liquid-crystalline polymer system designed for development into electromechanical actuators is described. The chemical structure is chosen to provide a large electroclinic effect in the SmA phase, with large concomitant layer shrinkage (a rare combination). The polymers are prepared by acyclic diene metathesis polymerization (ADMET) of liquid-crystalline ,-dienes. Oligomers with a degree of polymerization of ∼10−30 are obtained using Grubbs first-generation catalyst, while oligomers with a degree of polymerization of ∼200 are obtained using Grubbs second-generation catalyst. All polymer samples show the following phase sequence:  I − SmA − SmC − Glass. X-ray analysis of polymer powder samples demonstrates the desired layer shrinkage at the SmA − SmC transition. The polymers form well-aligned fibers by pulling from the isotropic melt, and X-ray analysis of fibers in the SmA phase shows that in the bulk of the fiber the layers are oriented perpendicular to the fiber axis, while at the surfaces there appears to be a thin sheath where the layers are parallel to the fiber/air interface. The desired layer shrinkage with tilt at the SmA − SmC transition in these fibers is seen as well, and in the SmC phase the fibers exhibit an interesting conical chevron layer structure. Electro-optic investigation of aligned thin films of the polymer, prepared from quenched fiber glasses using a novel technique, exhibit a large electroclinic effect, with substantial degradation of alignment quality upon field-induced tilt. This degradation in alignment quality, coupled with the layer shrinkage at the SmA − SmC transition demonstrated by X-ray scattering, strongly suggests the desired layer shrinkage with electroclinic tilt is in fact occurring in the polymer films.

Published
2006
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42. Frustration of polarity and chirality in a binary mixture of bent-core mesogens

Author

Nakata, Michi, Link, Darren R., Thisayukta, Jirakorn, Takanishi, Yoichi, Ishikawa, Ken, Watanabe, Junji, and Takezoe, Hideo

Abstract

In order to investigate polar order and chiral layer structures in bent-core mesogens, mixtures of synclinic antiferroelectric (achiral P-8-OPIMB) and anticlinic ferroelectric (chiral P-8-OPIMB6*) liquid crystals were studied. The binary phase diagram of these materials was produced based on detailed texture observations and measurements of the dielectric response and polarization-reversal current. A synclinic ferroelectric state is found to dominate in mixtures having 38% chiral content in 6 µm thick cells. This structure is a hybrid of the structures of the two parent materials taking the synclinic tilt from P-8-OPIMB and the ferroelectric polar order from P-8-OPIMB6*. Intermolecular steric interactions at the interface of adjacent smectic layers are thought to play a role in determining the ground state structure in the mixtures.

Published
2001

43. Electronic electrooptic phase modulation using bent-core liquid crystals.

Author

Rickard, Malcolm, Nakata, Michi, Takezoe, Hideo, Watanabe, Junji, and Clark, Noel A.

Subjects
*POLARIZABILITY (Electricity), *FERROELECTRIC crystals, *LIQUID crystals, *REFRACTIVE index, *ELECTROOPTICS, *POLYMERS, *PHYSICS
Abstract

The electronic contribution to the second-order nonlinear polarizability of a ferroelectric liquid-crystal phase formed by the spontaneously polar organization of bent-core molecules has been demonstrated. Application of a 40 MHz driving voltage and measurement of the refractive index modulation of light of wavelength 1.3 μm yields electrooptic coefficients r∼10 pm/V, comparable to that found in poled polymers. [ABSTRACT FROM AUTHOR]

Published
2005
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44. Charge controlled, fixed optic axis analog (“v-shaped”) switching of a bent-core ferroelectric liquid crystal.

Author

O'Callaghan, Michael J., Wand, Michael D., Walker, Christopher M., and Nakata, Michi

Subjects
FERROELECTRIC crystals, OPTICAL polarization, OPTICS, CRYSTALS, ELECTROMAGNETIC induction, ENGINEERING
Abstract

Recently discovered anticlinic ferroelectric liquid crystals (FLCs) offer a mode of fast fixed-optic-axis electro-optic modulation useful for a variety of applications. In addition, the high spontaneous polarization of a member of this class of FLCs (∼500–600 nC/cm2) suggests that it is a good candidate for electrostatically controlled thresholdless analog switching, whereas conventional SmC* FLCs have a binary response. Using a simple charge control drive circuit, we have found that this FLC is in fact capable of hysteresis-free analog switching. An optical model suggests that this class of FLCs might be engineered to have a much larger electro-optic effect than seen in this example. [ABSTRACT FROM AUTHOR]

Published
2004
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45. Smectic A and smectic C materials: partially deuteriated chiral liquid crystals (S)-([sup -] )-2-methylbuty 4-(4-(d[sub 13] )-hexyloxyphenyl)benzoate and (S)-([sup -] )-2-methylbutyl 4...

Author

Yeap, Guan-Yeow, Guan-Yeow Yeap, Nakata, Michi, Takanishi, Yoichi, Ishikawa, Ken, and Takezoe, Hideo

Subjects
FERROELECTRIC crystals, LIQUID crystals, BENZOATES, COMPLEX compounds
Abstract

In order to study the difference in microscopic orientation of ferro- and antiferroelectric liquid crystalline molecules, we synthesized the partially deuteriated chiral compounds, (S)-([sup -] )-2-methylbutyl 4-(4-(d[sub 13] )-hexyloxy- and (S)-([sup -] )-2-methylbutyl 4-(4-(d[sub 17] )-octyloxy-phenyl)benzoates. Fundamental physical properties such as phase transition temperatures, spontaneous polarization and tilt angle were determined. Polarized FTIR measurements were also made to provide information on molecular structure and orientation. [ABSTRACT FROM AUTHOR]

Published
2000
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46. Electric-field-induced transition between the polarization-modulated and ferroelectric smectic- C(S) P(F)* liquid crystalline states studied using microbeam x-ray diffraction.

Author

Nakata M, Link DR, Takanishi Y, Takahasi Y, Thisayukta J, Niwano H, Coleman DA, Watanabe J, Iida A, Clark NA, and Takezoe H

Abstract

We report x-ray microbeam studies of a bent-core liquid crystalline material with chiral citronellyl tails. This material has an equilibrium polarization-modulated smectic- CP (PM-SmCP) state exhibiting the B7 texture upon slow cooing from the isotropic while a metastable chiral synclinic ferroelectric Sm-CP state (Sm- C(S) P(*)(F) ) is obtained on quenching from the isotropic. The polarization modulated phase PM-Sm C(S) P(*)(F) shows typical x-ray patterns having multiple satellite peaks around the first-order layer reflection, indicating undulated layers, while the metastable Sm- C(S) P(*)(F) state exhibits a single layering peak indicating flat layers. The Sm- C(S) P(*)(F) state is also induced by the application of an electric field larger than the threshold field ( E(th) ) and thermally returns to the polarization modulated PM-Sm C(S) P(*)(F) structure.

Published
2005
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47. Flexoelectric polarization in hybrid nematic films.

Author

Link DR, Nakata M, Takanishi Y, Ishikawa K, and Takezoe H

Abstract

Hybrid films of the nematic liquid crystal penthylcyanobiphenyl (5CB) on the surface of glycerol were studied in the presence of an in-plane electric field. In this geometry there is a macroscopic flexoelectric polarization P(f) with a component in the film plane that couples linearly to the field. Here we report the electric field and film thickness dependence of the width of the 2pi reorientations (2pi walls) in the c director that are trapped by the field and interpret these observations based on continuum elastic theory. We find the difference between the flexoelectric coefficients to be e(1)-e(3)=+11 pC/m.

Published
2002
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