39.3: Sub-Millisecond Liquid Crystal Mode Utilizing Electro-Optic Kerr Effect Comprising Polymer-Stabilized Isotropic Liquid Crystals

ABSTRACTFerroelectric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to their inherently fast switching speeds and bistability. Recently, considerable research has been devoted to FLCs mechanically stabilized by a polymer network. The network is formed typically by in situ polymerization of a monomer dissolved in the FLC. Because of the inherent order in the FLC, the polymerization behavior may be significantly different than what might be expected in solution polymerizations. These deviations result largely from the segregation properties of the monomer in the liquid crystal. One class of monomers, namely fluorinated acrylates, is a likely candidate for inducing novel segregation, polymerization and electro-optic behavior in polymer stabilized ferroelectric liquid crystals (PSFLCs). The use of fluorinated moieties has a significant impact on the phase and polymerization behavior of liquid crystal systems. This study focuses on the polymerization of a fluorinated diacrylate, octafluoro 1,6-hexanediol diacrylate (FHDDA), to form PSFLCs and the consequent impact of the polymerization on the ultimate performance. Interestingly, as the temperature is increased and the order of the system decreases, a dramatic increase in the polymerization rate is observed. This increase is especially prominent for polymerizations in the smectic C* phase for which the rate is more than five times that exhibited at much higher temperatures in the isotropic phase. As with other monomer/FLC systems, the segregation of the monomer plays a role in this polymerization behavior as the monomer segregates between the smectic layers of the liquid crystal. The segregation properties also significantly impact the ultimate electro-optic properties. Both ferroelectric polarization and response time of the PSFLC change markedly with different polymerization temperatures, and approach values very close to those of the neat FLC under appropriate polymerization conditions. This behavior not only provides a unique mechanism for rate acceleration in PSFLCs, but also paves the way for new methods to optimize performance in these materials.

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Investigation of Kerr effect in a blue phase liquid crystal using wedge-cell technique

Photonics Letters of Poland ◽

10.4302/plp.v9i2.738 ◽

2017 ◽

Vol 9 (2) ◽

pp. 54 ◽

Cited By ~ 2

Author(s):

Kamil Orzechowski ◽

Marek Wojciech Sierakowski ◽

Marzena Sala-Tefelska ◽

Tomasz Ryszard Woliński ◽

Olga Strzeżysz ◽

...

Keyword(s):

Refractive Index ◽

Liquid Crystal ◽

Liquid Crystals ◽

Electric Field ◽

Kerr Effect ◽

Beam Steering ◽

Phase Liquid ◽

Blue Phase ◽

Blue Phases ◽

Polymer Stabilized

In this work an alternative method for refractive index measurement of blue phase liquid crystal in the Kerr effect has been described. The proposed wedge method uses simple goniometric setup, allowing for direct index measurements for any wavelengths and index values. This is significant advantage comparing to other methods, usually having limitations of the measurement range as well as necessity complicated calculation to obtain refractive indices values. The results are reliable and agree well with the subject literature. Full Text: PDF ReferencesW. Cao et al., "Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II", Nat. Mater. 1, 111-113 (2002). CrossRef S. Meiboom, M. Sammon, W.F. Brinkman, "Lattice of disclinations: The structure of the blue phases of cholesteric liquid crystals", Phys. Rev. A. 27, 438 (1983). CrossRef S. Tanaka et al., "Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy", Sci. Rep. 5, 16180 (2015). CrossRef Y. Li and S.-T. Wu, "Polarization independent adaptive microlens with a blue-phase liquid crystal", Opt. Express 19(9), 8045-8050 (2011). CrossRef N. Rong et al., "Polymer-Stabilized Blue-Phase Liquid Crystal Fresnel Lens Cured With Patterned Light Using a Spatial Light Modulator", J. of Disp. Technol. 12(10), 1008-1012 (2016). CrossRef J.-D. Lin et al., "Spatially tunable photonic bandgap of wide spectral range and lasing emission based on a blue phase wedge cell", Opt. Express 22(24), 29479-29492 (2014). CrossRef P. Joshi et al., "Tunable light beam steering device using polymer stabilized blue phase liquid crystals", Photon. Lett. Poland 9(1), 11-13 (2017). CrossRef Ch.-W. Chen et al., "Temperature dependence of refractive index in blue phase liquid crystals", Opt. Mater. Express 3(5), 527-532 (2013). CrossRef Y.-H. Lin et al., "Measuring electric-field-induced birefringence in polymer stabilized blue-phase liquid crystals based on phase shift measurements", J. Appl. Phys. 109, 104503 (2011). CrossRef J. Yan et al., "Direct measurement of electric-field-induced birefringence in a polymer-stabilized blue-phase liquid crystal composite", Opt. Express 18(11), 11450-11455 (2010). CrossRef K.A. Rutkowska, K. Orzechowski, M. Sierakowski, "Wedge-cell technique as a simple and effective method for chromatic dispersion determination of liquid crystals", Photon. Lett. Poland 8(2), 51-53 (2016). CrossRef O. Chojnowska et al., "Electro-optical properties of photochemically stable polymer-stabilized blue-phase material", J. Appl. Phys. 116, 213505 (2014). CrossRef J. Yan et al., "Extended Kerr effect of polymer-stabilized blue-phase liquid crystals", Appl. Phys. Lett. 96, 071105 (2010). CrossRef M. Chen et al., "Electrically assisting crystal growth of blue phase liquid crystals", Opt. Mater. Express 4(5), 953-959 (2014). CrossRef J. Kerr, Philos. Mag. 50, 337 (1875).

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Optically isotropic liquid crystal media formulated by doping star-shaped cyclic oligosiloxane liquid crystal surfactants in twin nematic liquid crystals

Soft Matter ◽

10.1039/c5sm00005j ◽

2015 ◽

Vol 11 (19) ◽

pp. 3772-3779 ◽

Cited By ~ 11

Author(s):

Namil Kim ◽

Dae-Yoon Kim ◽

Minwook Park ◽

Yu-Jin Choi ◽

Soeun Kim ◽

...

Keyword(s):

Liquid Crystal ◽

Liquid Crystals ◽

Nematic Liquid Crystals ◽

Isotropic Liquid

The formation of an optically isotropic liquid crystal (LC) medium by doping the star-shaped LC molecular surfactant in a nematic LC medium may allow us to develop new electro-optical LC devices.

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Effect of a Trifluorophenyl-Based Monomer on the Electro-optic Performances of Polymer-Stabilized Blue Phase Liquid Crystals

Brazilian Journal of Physics ◽

10.1007/s13538-020-00792-5 ◽

2020 ◽

Vol 50 (6) ◽

pp. 687-698

Author(s):

Minggang Hu ◽

Jiangwei Li ◽

Nejmettin Avci

Keyword(s):

Liquid Crystals ◽

Electro Optic ◽

Phase Liquid ◽

Blue Phase ◽

Polymer Stabilized

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Near infrared Kerr effect and description of field-induced phase transitions in polymer-stabilized blue phase liquid crystals

Applied Physics Letters ◽

10.1063/1.4942604 ◽

2016 ◽

Vol 108 (8) ◽

pp. 081107

Author(s):

B. Atorf ◽

H. Rasouli ◽

G. Nordendorf ◽

D. Wilkes ◽

H. Kitzerow

Keyword(s):

Phase Transitions ◽

Liquid Crystals ◽

Kerr Effect ◽

Near Infrared ◽

Phase Liquid ◽

Blue Phase ◽

Polymer Stabilized

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Polymer Stabilized Liquid Crystal Smart Window with Flexible Substrates Based on Low-Temperature Treatment of Polyamide Acid Technology

Polymers ◽

10.3390/polym11111869 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1869 ◽

Cited By ~ 2

Author(s):

Yang Zhang ◽

Changrui Wang ◽

Wei Zhao ◽

Ming Li ◽

Xiao Wang ◽

...

Keyword(s):

Liquid Crystal ◽

Temperature Treatment ◽

Flexible Substrates ◽

Smart Window ◽

Alignment Layer ◽

Low Temperature Treatment ◽

Electro Optic ◽

Lower Temperature ◽

Polymer Stabilized ◽

Pet Substrate

Polymer stabilized liquid crystal (PSLC) devices can be used as smart privacy windows that switch between transparent and opaque states. The polyimide alignment layer of a PSLC device is usually obtained by the treatment of polyamide acid (PAA) with temperatures over 200 °C. This hinders the fabrication of PSLC devices on flexible substrates, which melt at these high temperatures. In this work, the fabrication of a PSLC alignment layer using a lower temperature that is compatible with most flexible substrates, is demonstrated. It was found that the treatment of PAA at 150 °C could generate the same alignment for liquid crystals. Based on this, a PSLC device was successfully fabricated on a flexible polyethylene terephthalate (PET) substrate, demonstrating excellent electro-optic performances.

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