You searched for subject:(liquid crystals).
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1.
McCamley, Maureen K.
Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin.
Degree: PhD, Biomedical Engineering, 2009, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:149/ 
► This dissertation describes translational research conducted to develop a rapid diagnostic for the detection of endotoxin using liquid crystal sensor technology. Due to the elastic…
(more)
▼ This dissertation describes translational research
conducted to develop a rapid diagnostic for the detection of
endotoxin using
liquid crystal sensor technology. Due to the
elastic nature of bulk nematic
liquid crystal, small changes in
surface anchoring at the interface between the
liquid crystal
sensor and the targeted biomolecule (endotoxin) are amplified,
allowing optical detection through polarizing microscopy.
Theoretical simulations (a phenomenological Landau-de Gennes model)
were applied to understand and predict the behavior of the confined
nematic. Simulated optical micrographs were compared with
experiments to understand the nematic profiles and to control and
optimize the sensor in a specific regime. Distinct optical patterns
were detected when the sensor was exposed to air and to water. A
structural transition in the nematic structure was observed, driven
by changes in the anchoring strength at the open surface of the
sensor. This change was leveraged and used to detect the presence
of both a model surfactant and the targeted biomolecule at the open
surface. The response of the sensor can be controlled by changing
certain experimental parameters, such as the depth, aspect ratio,
anchoring strength and nematic material. Isolated
lipopolysaccharide (LPS) was detected in concentrations varying
from 1 mg/mL to 10 ug/mL, giving a very strong and quantifiable
response of the sensor.
Advisors/Committee Members: Crawford, Gregory (director), Artenstein, Andrew (director), Artenstein, Andrew (reader), Tripathi, Anubhav (reader), Opal, Steven (reader), Zumer, Slobodan (reader).
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
McCamley, M. K. (2009). Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:149/
Chicago Manual of Style (16th Edition):
McCamley, Maureen K. “Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin.” 2009. Doctoral Dissertation, Brown University. Accessed March 02, 2021.
https://repository.library.brown.edu/studio/item/bdr:149/.
MLA Handbook (7th Edition):
McCamley, Maureen K. “Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin.” 2009. Web. 02 Mar 2021.
Vancouver:
McCamley MK. Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin. [Internet] [Doctoral dissertation]. Brown University; 2009. [cited 2021 Mar 02].
Available from: https://repository.library.brown.edu/studio/item/bdr:149/.
Council of Science Editors:
McCamley MK. Development of a Liquid Crystal Biosensor for the Detection
of Endotoxin. [Doctoral Dissertation]. Brown University; 2009. Available from: https://repository.library.brown.edu/studio/item/bdr:149/
Hong Kong University of Science and Technology
2.
Ma, Ying.
Electrically suppressed helix ferroelectric liquid crystal and its applications.
Degree: 2015, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-86346
;
https://doi.org/10.14711/thesis-b1487608
;
http://repository.ust.hk/ir/bitstream/1783.1-86346/1/th_redirect.html
► By making use of the unique properties of liquid crystal materials, liquid crystal displays (LCDs) as well as many other liquid crystal photonic devices have…
(more)
▼ By making use of the unique properties of liquid crystal materials, liquid crystal displays (LCDs) as well as many other liquid crystal photonic devices have been playing an important role in serving our daily life. Many LC devices need to have fast response time as well as good electrooptical properties. Ferroelectric liquid crystal, well known for its fast response time, can be a good candidate for a variety of applications. A new proposed FLC mode called electrically suppressed helix (ESH) FLC is characterized by fast response, high contrast ratio, good mechanical stability with low driving voltage has attract of much attention. In this thesis, the properties for ESH FLC are introduced in detail and polymer stabilized ESH FLC have been proposed to further stabilize the optical properties to make it suitable for some applications. By using the ESH FLC, two optical element structures are produced: gratings and fork gratings. For gratings, we have demonstrated the switchable and optical rewritable grating structure based on FLCs with ultra-fast switching speed and high diffraction efficiency at small electric field. The response time of 50µs at 6.67V/μm has been achieved. Two modes are demonstrated: GRATING/OFF mode and GRATING/TRANSMISSION mode. The proposed grating can be erased, re-written optically for different grating profiles with simple steps. Theoretical calculations have been made for both modes and the FLC cone angle effect on diffraction efficiency is discussed in detail to further explain the advantage of this material. All the experimental results fit the theoretical calculations very well. For fork gratings, we have demonstrated the switchable fork grating structure based on FLCs with ultra-fast switching speed and high diffraction efficiency at small electric field. Two modes are introduced: FORKGRATING/OFF mode and FORKGRATING/TRANSMISSION mode. Furthermore, using DMD system provides us a very easy way to fabricate the fork grating cell with very high alignment quality. We believe this method shows great potential to find application as element for projection display, Pico-projectors and various photonic elements. Another approch is that we propose a new type of display-field sequential color display based on ESH FLC which shows many advantages. The main obstacle for this kind of display is that it requires fast response time LC to eliminate color breakup. So we proposed the display cell with ultra fast response time and good electro-optical properties. We manage the display quality in many ways to get the best contrast ratio, color gamut, response time and stability. Two different display modes have been introduced. For transmissive mode, we have given the results for many display parameters and shown good quality of our display cell. We also build up our own prototypes including prototypes of manually changing colors, automatically changing colors and the multiple pixels display. For reflective mode, we have obtained some preliminary results which can show its fast response time with…
Subjects/Keywords: Ferroelectric crystals
; Liquid crystals
; Liquid crystal devices
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APA (6th Edition):
Ma, Y. (2015). Electrically suppressed helix ferroelectric liquid crystal and its applications. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-86346 ; https://doi.org/10.14711/thesis-b1487608 ; http://repository.ust.hk/ir/bitstream/1783.1-86346/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Ma, Ying. “Electrically suppressed helix ferroelectric liquid crystal and its applications.” 2015. Thesis, Hong Kong University of Science and Technology. Accessed March 02, 2021.
http://repository.ust.hk/ir/Record/1783.1-86346 ; https://doi.org/10.14711/thesis-b1487608 ; http://repository.ust.hk/ir/bitstream/1783.1-86346/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Ma, Ying. “Electrically suppressed helix ferroelectric liquid crystal and its applications.” 2015. Web. 02 Mar 2021.
Vancouver:
Ma Y. Electrically suppressed helix ferroelectric liquid crystal and its applications. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2015. [cited 2021 Mar 02].
Available from: http://repository.ust.hk/ir/Record/1783.1-86346 ; https://doi.org/10.14711/thesis-b1487608 ; http://repository.ust.hk/ir/bitstream/1783.1-86346/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Ma Y. Electrically suppressed helix ferroelectric liquid crystal and its applications. [Thesis]. Hong Kong University of Science and Technology; 2015. Available from: http://repository.ust.hk/ir/Record/1783.1-86346 ; https://doi.org/10.14711/thesis-b1487608 ; http://repository.ust.hk/ir/bitstream/1783.1-86346/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Alberta
3.
Wang, Kejie.
On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen.
Degree: MS, Department of Chemical and Materials
Engineering, 2015, University of Alberta
URL: https://era.library.ualberta.ca/files/2j62s7420
► Hydrocarbon-based liquid crystal domains have been identified in unreacted heavy fractions of petroleum from Athabasca bitumen and other hydrocarbon resources worldwide. These liquid crystal domains…
(more)
▼ Hydrocarbon-based liquid crystal domains have been
identified in unreacted heavy fractions of petroleum from Athabasca
bitumen and other hydrocarbon resources worldwide. These liquid
crystal domains have also been shown to transfer from the
hydrocarbon-rich phase to the water-rich phase during SAGD
production, and primary separation of mined bitumen where their
composition is enriched relative to bitumen and inorganic
constituents. In this work, liquid crystal rich material was
further isolated from SAGD produced water that also contains
dispersed drops of bitumen rich material mineral matter and clay
among its constituents. The physical and chemical isolation methods
are described and the outcomes are validated using cross-polarized
light microscopy and chemical analysis, including: elemental
analysis and Fourier Transform Ion Cyclotron Resonance Mass
Spectrometry (FT-ICR MS) using a negative-ion Electrospray
Ionization (ESI) source (heteroatom class distributions, detailed
DBE and O/C ratio). From the elemental and other analyses, the
liquid crystal rich material is shown to include humic substances
(humic acid, fulvic acid, humin) among the principal components as
these are the only categories of species known to be present that
have high enough oxygen contents to meet the mass balance
constraint imposed by the elemental analysis. Naphthenic acids and
other potential candidate species do not have high enough oxygen
contents comprise a significant mass fraction of the
constituents.
Subjects/Keywords: Liquid Crystals; Bitumen
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APA (6th Edition):
Wang, K. (2015). On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen. (Masters Thesis). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/2j62s7420
Chicago Manual of Style (16th Edition):
Wang, Kejie. “On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen.” 2015. Masters Thesis, University of Alberta. Accessed March 02, 2021.
https://era.library.ualberta.ca/files/2j62s7420.
MLA Handbook (7th Edition):
Wang, Kejie. “On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen.” 2015. Web. 02 Mar 2021.
Vancouver:
Wang K. On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen. [Internet] [Masters thesis]. University of Alberta; 2015. [cited 2021 Mar 02].
Available from: https://era.library.ualberta.ca/files/2j62s7420.
Council of Science Editors:
Wang K. On the Separation and Composition of Liquid Crystals in
Athabasca Bitumen. [Masters Thesis]. University of Alberta; 2015. Available from: https://era.library.ualberta.ca/files/2j62s7420
Louisiana State University
4.
Collins, Melissa Elizabeth.
Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals.
Degree: PhD, Chemistry, 2013, Louisiana State University
URL: etd-10172013-230022
;
https://digitalcommons.lsu.edu/gradschool_dissertations/3706
► Silica-polypeptide hybrid particles are core-shell colloids. Established synthetic methods ensure uniformly sized cores and provide the ability to have magnetic or fluorescent inclusions. The polypeptide…
(more)
▼ Silica-polypeptide hybrid particles are core-shell colloids. Established synthetic methods ensure uniformly sized cores and provide the ability to have magnetic or fluorescent inclusions. The polypeptide shell is highly functional in its ability to respond to stimuli through changes in shape and formation of ordered phases above certain concentrations or temperatures. This research explores the interactions of hybrid particles mixed with polypeptides dispersed in solution. Depletion theory, which considers mainly entropic interactions between particles, can be used to explain the phase behavior of colloids. Due to the chemical similarities between the polypeptides attached to the surface and those free in solution, enthalpic interactions are considered to be negligible. The primary polypeptide employed in this dissertation is poly (gamma-benzyl-L-glutamate), PBLG, which is capable of forming liquid crystalline phases on its own. Phase behavior of the colloidal particles combined with polypeptides was monitored by polarized optical microscopy (POM) to determine the onset of the liquid crystalline phase. Wide-angle X-ray scattering (WAXS) was used to gain information about the crystalline structure of the mixtures. Further characterization of hybrid particles by hydrodynamic modeling established that their behavior is indeed core-shell in solution and depends on shell density and length. Poly (tetrafluoroethylene) latex was analyzed by depolarized dynamic light scattering (DDLS) as a precursor to the study of magnetic hybrid particles which also have a depolarizing affect.
Subjects/Keywords: liquid crystals; colloids
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APA (6th Edition):
Collins, M. E. (2013). Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-10172013-230022 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3706
Chicago Manual of Style (16th Edition):
Collins, Melissa Elizabeth. “Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals.” 2013. Doctoral Dissertation, Louisiana State University. Accessed March 02, 2021.
etd-10172013-230022 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3706.
MLA Handbook (7th Edition):
Collins, Melissa Elizabeth. “Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals.” 2013. Web. 02 Mar 2021.
Vancouver:
Collins ME. Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals. [Internet] [Doctoral dissertation]. Louisiana State University; 2013. [cited 2021 Mar 02].
Available from: etd-10172013-230022 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3706.
Council of Science Editors:
Collins ME. Phase behavior of silica-polypeptide hybrid particles immersed in cholesteric liquid crystals. [Doctoral Dissertation]. Louisiana State University; 2013. Available from: etd-10172013-230022 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3706
University of Oxford
5.
Cortes, Louis.
Colloidal liquid crystals : phase behavior, dynamics and confinement.
Degree: PhD, 2019, University of Oxford
URL: http://ora.ox.ac.uk/objects/uuid:4f06a6fa-318e-4a17-b98f-e706144eb492
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.786242
► In this thesis, we report on the phase behaviour, dynamics and confinement of micron-sized colloidal silica rods with small gravitational length. In sedimentation-diffusion equilibrium, distinct…
(more)
▼ In this thesis, we report on the phase behaviour, dynamics and confinement of micron-sized colloidal silica rods with small gravitational length. In sedimentation-diffusion equilibrium, distinct isotropic, nematic, smectic and crystal phases are found to coexist within tens of micrometers. By combining confocal microscopy and tracer particles, the rods' phase behavior and dynamics are characterized across the whole phase diagram in a single sedimentation-diffusion experiment. Our experimental approach allows to quantitatively compare the sedimentation-diffusion equilibrium of charged rods with theoretical predictions. All predicted phases are observed. However, the thickness of the upper sediment - counting the isotropic, nematic and smectic regions - is found to be inflated with respect to the hard rod prediction, up to a factor 2. We consider the possible effect of polydispersity, electrostatic repulsion and the entropy of counterions (Donnan effect). We conclude that only the Donnan effect can explain the observed inflation. To support the hypothesis, we independently determine the surface charge of silica rods and discuss the results. Subsequently, we measure the self-diffusion of rod-like particles in sedimentation-diffusion equilibrium. Firstly, a molecular dynamic simulation is used to test the method. The self-diffusion coefficients are measured across the whole phase diagram and compared to bulk simulations -without gravity. We then present experimental results for an aspect ratio of 10, which has not been yet reported upon in literature. We reproduce most trends predicted by simulations. In particular, we find evidence of strong correlation between rotational and translational diffusion approaching the nematic phase, and a crossover between diffusion parallel and perpendicular to the nematic director in the smectic phase. However, we measure smaller diffusion coefficients than predicted by simulation, which is consistent with work on viral colloidal liquid crystals with larger aspect ratio. Finally, we study sedimentation-diffusion equilibrium in confinement, with a focus on the smectic phase, and consider three geometries: the square, the lozenge and the annulus. The interplay between boundary conditions, elasticities and defects lead to a host of different structures. In squares and disks, we mostly observe the smectic bridge state. However, by transforming the shapes into annuli and lozenges, we force new configurations. The transitions are characterized in light of phenomenological models to extract the ratios between: the energy of an edge dislocation, the energy of a disclination line and the bending energy of smectic layers.
Subjects/Keywords: Colloids; Liquid crystals
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APA (6th Edition):
Cortes, L. (2019). Colloidal liquid crystals : phase behavior, dynamics and confinement. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:4f06a6fa-318e-4a17-b98f-e706144eb492 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.786242
Chicago Manual of Style (16th Edition):
Cortes, Louis. “Colloidal liquid crystals : phase behavior, dynamics and confinement.” 2019. Doctoral Dissertation, University of Oxford. Accessed March 02, 2021.
http://ora.ox.ac.uk/objects/uuid:4f06a6fa-318e-4a17-b98f-e706144eb492 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.786242.
MLA Handbook (7th Edition):
Cortes, Louis. “Colloidal liquid crystals : phase behavior, dynamics and confinement.” 2019. Web. 02 Mar 2021.
Vancouver:
Cortes L. Colloidal liquid crystals : phase behavior, dynamics and confinement. [Internet] [Doctoral dissertation]. University of Oxford; 2019. [cited 2021 Mar 02].
Available from: http://ora.ox.ac.uk/objects/uuid:4f06a6fa-318e-4a17-b98f-e706144eb492 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.786242.
Council of Science Editors:
Cortes L. Colloidal liquid crystals : phase behavior, dynamics and confinement. [Doctoral Dissertation]. University of Oxford; 2019. Available from: http://ora.ox.ac.uk/objects/uuid:4f06a6fa-318e-4a17-b98f-e706144eb492 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.786242
Indian Institute of Science
6.
Deepak, H S vinay.
NMR Investigations Of Oriented Systems : Novel Techniques And Applications.
Degree: PhD, Faculty of Science, 2011, Indian Institute of Science
URL: http://etd.iisc.ac.in/handle/2005/1077
► This thesis presents results of novel methodologies applied to oriented systems. Both pure liquid crystalline materials as well as molecules oriented in liquid crystalline matrices…
(more)
▼ This thesis presents results of novel methodologies applied to oriented systems. Both pure
liquid crystalline materials as well as molecules oriented in
liquid crystalline matrices have been studied. In particular this thesis presents investigations related to various aspects of NMR in
liquid crystalline media, such as, assignment of resonances and the study of director dynamics of spinning
liquid crystals in different phases and with different symmetry. Simplified methods for structure determination of solutes dissolved in
liquid crystal solvents have been proposed. Diffusion ordered spectroscopy has been used to study a mixture of
liquid crystals of opposite diamagnetic susceptibility at its coexistent phase. The methods presented represent novel techniques to characterize the
liquid crystalline phase.
NMR spectroscopy which has become a method of choice for understanding ordering mechanisms of mesogens requires a robust method for obtaining assignments of the NMR spectra of various nuclei that are found in the mesogens [1, 2]. It turns out that the spectra in the isotropic phase and in the nematic phase of a
liquid crystal molecule are very different due to the presence of chemical shift anisotropy in the mesophase spectrum. There are a host of methodologies available for assigning spectra in the isotropic phase [3]. These methods however fail, when applied to the spectrum of the molecules in the mesophase due to the dominating role of strong anisotropic interactions, such as homonuclear couplings among protons. Problems arising while assigning spectral lines of
liquid crystals in their nematic phase have been dealt with in chapter 2. To circumvent these problems, a property of the
liquid crystal molecules under off-magic angle sample spinning can be utilized. It has been shown by Courtieu et al. [4] that the director/symmetry axis of a Δχ + ve
liquid crystal aligns along the spinning axis for θ between 0 ° and θm, where θ is the angle between the spinning axis and the magnetic field and θm = 54.7° is the magic angle. It may be noted that the spectrum of θ = 0° spinning angle corresponds to the normal static spectrum, while the spectrum of θ = θm corresponds to the isotropic spectrum. In an earlier study, Teearr et al. [5] had recorded the 13C
liquid crystal spectra as a function of very closely spaced θ values from 90° all the way up to 0°. From these plots of chemical shift versus the angle of spinning, it is possible to follow the trajectory of each 13C line from its position from θ = θm to θ = 0° and then match the spectrum in the isotropic phase (equivalently the magic angle sample spinning spectrum of the nematic phase) to the spectrum of the static sample in the nematic phase. However this method requires recording spectra at closely spaced angle intervals, so that one can unambiguously follow the trajectory of each of the lines without missing out any crossover of trajectories. However, this operation is time consuming. In this thesis we propose an alternate method, where we utilize the fact that the above…
Advisors/Committee Members: Ramanathan, K V (advisor).
Subjects/Keywords: Nuclear Magnetic Resonance; Liquid Crystals; Anisotropy; Biaxiality; Lyotropic Liquid Crystals; Thermotropic Liquid Crystals; Liquid Crystals - NMR Spectroscopy; Nematic Liquid Crystal; Magnetism
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APA (6th Edition):
Deepak, H. S. v. (2011). NMR Investigations Of Oriented Systems : Novel Techniques And Applications. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/1077
Chicago Manual of Style (16th Edition):
Deepak, H S vinay. “NMR Investigations Of Oriented Systems : Novel Techniques And Applications.” 2011. Doctoral Dissertation, Indian Institute of Science. Accessed March 02, 2021.
http://etd.iisc.ac.in/handle/2005/1077.
MLA Handbook (7th Edition):
Deepak, H S vinay. “NMR Investigations Of Oriented Systems : Novel Techniques And Applications.” 2011. Web. 02 Mar 2021.
Vancouver:
Deepak HSv. NMR Investigations Of Oriented Systems : Novel Techniques And Applications. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2011. [cited 2021 Mar 02].
Available from: http://etd.iisc.ac.in/handle/2005/1077.
Council of Science Editors:
Deepak HSv. NMR Investigations Of Oriented Systems : Novel Techniques And Applications. [Doctoral Dissertation]. Indian Institute of Science; 2011. Available from: http://etd.iisc.ac.in/handle/2005/1077
Hong Kong University of Science and Technology
7.
Wang, Lu.
Novel liquid crystal devices for display and photonics based on non-uniform alignment.
Degree: 2012, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-7780
;
https://doi.org/10.14711/thesis-b1198654
;
http://repository.ust.hk/ir/bitstream/1783.1-7780/1/th_redirect.html
► Liquid Crystal (LC) is widely used in the Display industry. Currently most of televisions, phones, computers and other electronic devices implement Liquid Crystal Displays (LCDs).…
(more)
▼ Liquid Crystal (LC) is widely used in the Display industry. Currently most of televisions, phones, computers and other electronic devices implement Liquid Crystal Displays (LCDs). The display system normally is composed of the backlight, the polarizer and the liquid crystal cell. The initial alignment of liquid crystal molecules is achieved by rubbing. The alignment of the LC molecules can only be changed by electric fields because these molecules have dipole moments along their directors, but not by any light. The backlight also consumes large amount of power. Optically Rewritable Liquid Crystal Display (ORW) makes use of the Photoalignment technique to achieve the image displays by exposing the LC cell with the polarized UV light. First the thermal stability of the photoalignment technique will be investigated to verify the quality of the photoalignment technique. 3D effect can also be integrated into the ORW cell with two methods: Stereoscopic and Auto-Stereoscopic. This thesis will discuss the procedure for preparing 3D ORW cells and show the experimental results. ORW cells can also find applications like phase grating devices. The grating patterns can be transferred from an amplitude mask to the cell. Liquid Crystals can also be used to make photonics devices because of its electro-optical properties. Most frequently seen are LC optical switches, phase retarders, sensors and lens. They usually derive from the birefringence of the refractive indices along the director and perpendicular to the director of a LC molecule. In this thesis, the beam steering devices which steers the beam continuously by changing the effective refractive index of the LC cell will be investigated. The principles, simulation and experimental results will be shown. To increase the efficiency, the simulation of the phase corrector will be discussed.
Subjects/Keywords: Liquid crystals
; Liquid crystals – Optical properties
; Liquid crystal displays
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APA (6th Edition):
Wang, L. (2012). Novel liquid crystal devices for display and photonics based on non-uniform alignment. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-7780 ; https://doi.org/10.14711/thesis-b1198654 ; http://repository.ust.hk/ir/bitstream/1783.1-7780/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Wang, Lu. “Novel liquid crystal devices for display and photonics based on non-uniform alignment.” 2012. Thesis, Hong Kong University of Science and Technology. Accessed March 02, 2021.
http://repository.ust.hk/ir/Record/1783.1-7780 ; https://doi.org/10.14711/thesis-b1198654 ; http://repository.ust.hk/ir/bitstream/1783.1-7780/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Wang, Lu. “Novel liquid crystal devices for display and photonics based on non-uniform alignment.” 2012. Web. 02 Mar 2021.
Vancouver:
Wang L. Novel liquid crystal devices for display and photonics based on non-uniform alignment. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2012. [cited 2021 Mar 02].
Available from: http://repository.ust.hk/ir/Record/1783.1-7780 ; https://doi.org/10.14711/thesis-b1198654 ; http://repository.ust.hk/ir/bitstream/1783.1-7780/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Wang L. Novel liquid crystal devices for display and photonics based on non-uniform alignment. [Thesis]. Hong Kong University of Science and Technology; 2012. Available from: http://repository.ust.hk/ir/Record/1783.1-7780 ; https://doi.org/10.14711/thesis-b1198654 ; http://repository.ust.hk/ir/bitstream/1783.1-7780/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Hong Kong University of Science and Technology
8.
Fan, Fan.
Liquid crystal patterned photoalignment : methods and applications.
Degree: 2013, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-81412
;
https://doi.org/10.14711/thesis-b1255441
;
http://repository.ust.hk/ir/bitstream/1783.1-81412/1/th_redirect.html
► The liquid crystal alignment is mainly defined by azimuthal angle and pretilt angle. The patterned alignment can have spatially variable azimuthal angles or pretilt angles.…
(more)
▼ The liquid crystal alignment is mainly defined by azimuthal angle and pretilt angle. The patterned alignment can have spatially variable azimuthal angles or pretilt angles. The general application of the patterned alignment layer is to spatially modulate light properties like phase, polarization and intensity. Photoalignment technology is today, one of the most promising technologies for use in the preparation of the patterned alignment structure. In order to prepare a patterned photoalignment layer in the azimuthal direction, polarized light is normally used. When different areas of the photoalignment layer are exposed to light with different polarizations, the patterned photoalignment layer is formed. In order to provide methods that are easy and simple for photo-patterning, four methods are studied in this thesis. These four methods will design different photo masks for generation light with spatially varying polarization using patterned quarter-wave plate, patterned half-wave plate, twisted nematic liquid crystal cell and a multi-retarder system, respectively. To verify the properties of these four methods, a series of optical elements are made and tested. By combining the patterned photoalignment technology with the nematic or ferroelectric liquid crystals, electrically tunable liquid crystal devices can be produced. To evaluate the performance of these tunable devices, tunable Dammann gratings have been made and tested, using both nematic and ferroelectric liquid crystals. The results show that the tunable Dammann gratings can be switched between diffractive and non-diffractive states. The technology of patterned photoalignment in the pretilt direction is also studied in this thesis. A new photoalignment material called CPL024 is used in the research. The photoalignment material has the property whereby the aligned pretilt angle can be tuned in the range of 10 to 890 under different light exposure energies. Using this material, circular and cylindrical tunable liquid crystal lenses are fabricated and tested.
Subjects/Keywords: Liquid crystals
; Liquid crystal displays
; Optical properties
; Polymer liquid crystals
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APA (6th Edition):
Fan, F. (2013). Liquid crystal patterned photoalignment : methods and applications. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-81412 ; https://doi.org/10.14711/thesis-b1255441 ; http://repository.ust.hk/ir/bitstream/1783.1-81412/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Fan, Fan. “Liquid crystal patterned photoalignment : methods and applications.” 2013. Thesis, Hong Kong University of Science and Technology. Accessed March 02, 2021.
http://repository.ust.hk/ir/Record/1783.1-81412 ; https://doi.org/10.14711/thesis-b1255441 ; http://repository.ust.hk/ir/bitstream/1783.1-81412/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Fan, Fan. “Liquid crystal patterned photoalignment : methods and applications.” 2013. Web. 02 Mar 2021.
Vancouver:
Fan F. Liquid crystal patterned photoalignment : methods and applications. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2013. [cited 2021 Mar 02].
Available from: http://repository.ust.hk/ir/Record/1783.1-81412 ; https://doi.org/10.14711/thesis-b1255441 ; http://repository.ust.hk/ir/bitstream/1783.1-81412/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Fan F. Liquid crystal patterned photoalignment : methods and applications. [Thesis]. Hong Kong University of Science and Technology; 2013. Available from: http://repository.ust.hk/ir/Record/1783.1-81412 ; https://doi.org/10.14711/thesis-b1255441 ; http://repository.ust.hk/ir/bitstream/1783.1-81412/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Otago
9.
Singh, Rinku.
Self gelling microemulsion systems for vaccine delivery
.
Degree: 2011, University of Otago
URL: http://hdl.handle.net/10523/1653
► Purpose: The increasing interest in new generation vaccines is based upon utilising highly purified proteins and peptides as antigens. However, a disadvantage of these subunit…
(more)
▼ Purpose: The increasing interest in new generation vaccines is based upon utilising highly purified proteins and peptides as antigens. However, a disadvantage of these subunit vaccines is that they are often poorly immunogenic. Therefore there is a need to develop new formulation strategies which can generate the desired immune responses and are both safe and efficacious. One important formulation strategy involves incorporating antigens in polymeric nanoparticles, while another formulation strategy involves the dispersion of antigens in a sustained release carrier with the aim of increasing the size of the immune response generated and perhaps avoiding the need for multiple immunisations. In this thesis the aim was to combine these two approaches by dispersion of polymeric nanoparticles loaded with the antigen into a sustained release delivery systems (a self gelling microemulsion). Two polymeric nanoparticles (poly(ethylcyanoacrylate), PECA and chitosan nanoparticles, CNP) were dispersed in self gelling microemulsion (ME) templates. Ovalbumin (Ova) and Quil A were used as model antigen and adjuvant respectively. Biocompatible microemulsions were developed by establishing pseudoternary phase diagrams and these were then characterised at 37 ˚C. Lamellar
liquid crystalline gel regions were found adjacent to the microemulsion regions in the phase diagrams. Upon addition of water or body fluids a phase transition from microemulsions to
liquid crystalline systems may occur, which may make these systems suitable for sustained antigen delivery, as the rate of diffusion within the
liquid crystalline phase is slower as compared to
liquid vehicles. The study investigated the influence of the oil and water composition of the microemulsions on viscosity and release of antigen dispersed in the microemulsion in molecular form and incorporated into nanoparticles from the microemulsions and
liquid crystalline gels. The ability of these formulations to generate immune responses towards Ova was also investigated in vivo.
Methods: The ME components consisted of isopropyl myristate, lecithin, ethanol, water and either decyl glucoside (DG) or capryl-caprylyl glucoside (CCG). The selected microemulsions had a surfactant: water (S:W) ratio of 9:1 and a surfactant: oil (S:O) ratio of 5.2: 4.8. Formulations were loaded with fluorescently labelled Ova (FITC-Ova) and used as polymerisation templates for the preparation of PECA nanoparticles by interfacial polymerisation. CNP were prepared separately by a precipitation/coacervation method facilitated by sodium sulphate. The viscosity of one phase and two phase
liquid crystalline gels (with and without nanoparticles incorporated) was determined using a cone and plate rheometer. A fluorometric assay was used to determine entrapment and in vitro release of FITC-Ova. An HPLC method was used to determine entrapment of Quil A in PECA nanoparticles and CNP. Self-gelling microemulsion templates containing Ova and Quil A either free or incorporated in nanoparticles were subsequently investigated in…
Advisors/Committee Members: Rades, Thomas (advisor).
Subjects/Keywords: microemulsion;
nanoparticles;
liquid crystals
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APA (6th Edition):
Singh, R. (2011). Self gelling microemulsion systems for vaccine delivery
. (Doctoral Dissertation). University of Otago. Retrieved from http://hdl.handle.net/10523/1653
Chicago Manual of Style (16th Edition):
Singh, Rinku. “Self gelling microemulsion systems for vaccine delivery
.” 2011. Doctoral Dissertation, University of Otago. Accessed March 02, 2021.
http://hdl.handle.net/10523/1653.
MLA Handbook (7th Edition):
Singh, Rinku. “Self gelling microemulsion systems for vaccine delivery
.” 2011. Web. 02 Mar 2021.
Vancouver:
Singh R. Self gelling microemulsion systems for vaccine delivery
. [Internet] [Doctoral dissertation]. University of Otago; 2011. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/10523/1653.
Council of Science Editors:
Singh R. Self gelling microemulsion systems for vaccine delivery
. [Doctoral Dissertation]. University of Otago; 2011. Available from: http://hdl.handle.net/10523/1653
Texas A&M University
10.
Chang, Ya-Wen.
Discotic Liquid Crystals and Polymersomes: Molecule Goniometers.
Degree: PhD, Chemical Engineering, 2012, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11635
► Controlling the assembly of amphiphilic molecules and micron-sized, disk-shaped particles at different length scales into ordered structures enables bottom-up organization which is of great interest…
(more)
▼ Controlling the assembly of amphiphilic molecules and micron-sized, disk-shaped particles at different length scales into ordered structures enables bottom-up organization which is of great interest to emerging technologies based on structured materials. The primary object of this work is the investigation of structure forming components - Zirconium phosphate (ZrP) discotic particles and polymersomes/ amphiphiles on their self-assembly and interactions.
The effect of bilayer architecture of polymersomes on surface reactivity was investigated via fluorescent probing method. Established through complementary experiments, correlation between reactivity and molecule diffusivity in polymer-rich environment revealed the mechanism of reduced reactivity when tethered reactive groups are located deeper within the hydrophilic polymer layer.
The phase diagram of charged nanoplatelets was constructed as a function of particle concentration, surface cation moiety, and ionic strength. Influence of surface cation on the isotropic-nematic transition was done by measuring the transition boundaries of discotic suspensions prepared by acid-base exfoliation reaction with a series of exfoliating agents. Furthermore, a novel phase transition was found, where platelet-platelet interaction was influenced synergistically by ionic strength and ion exchange. At low pH, directional inter-platelet attractions lead to the formation of low volume fraction colloidal gels. Alternative surface modification approaches, including biomolecule deposition and alkyl chain grafting were explored.
Finally, self-assembly of platelets in emulsions and oil-water interface was examined. Surface modification was applied to link surface properties to stable emulsion-forming ability in mixed surfactant-particle system. Emulsion uniformity was achieved by microfluidic flow focusing method. Surface engineering and interaction control was demonstrated throughout this work to be viable approaches to the fundamental understanding of collective behaviors of individual building blocks.
Advisors/Committee Members: Ugaz, Victor M. (advisor), Cheng, Zhengdong (advisor), Jayaraman, Arul (committee member), Cremer, Paul S. (committee member).
Subjects/Keywords: Colloids; Self-assembly; liquid crystals
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APA (6th Edition):
Chang, Y. (2012). Discotic Liquid Crystals and Polymersomes: Molecule Goniometers. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11635
Chicago Manual of Style (16th Edition):
Chang, Ya-Wen. “Discotic Liquid Crystals and Polymersomes: Molecule Goniometers.” 2012. Doctoral Dissertation, Texas A&M University. Accessed March 02, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11635.
MLA Handbook (7th Edition):
Chang, Ya-Wen. “Discotic Liquid Crystals and Polymersomes: Molecule Goniometers.” 2012. Web. 02 Mar 2021.
Vancouver:
Chang Y. Discotic Liquid Crystals and Polymersomes: Molecule Goniometers. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11635.
Council of Science Editors:
Chang Y. Discotic Liquid Crystals and Polymersomes: Molecule Goniometers. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11635
11.
Woltman, Scott Jeffrey.
Tunable liquid crystal lasers.
Degree: PhD, Physics, 2008, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:186/
► Liquid crystal lasers are dye-doped distributed feedback lasing systems. Fabricated by coupling the periodic structure of a liquid crystal medium with a fluorescent dye, the…
(more)
▼ Liquid crystal lasers are dye-doped distributed
feedback lasing systems. Fabricated by coupling the periodic
structure of a
liquid crystal medium with a fluorescent dye, the
emission from these systems is tunable by controlling the
liquid
crystal system – be it through electric or thermal field effects,
photochemical reactions, mechanical deformations, etc. The laser
action arises from an extended interaction time between the
radiation field, the laser emission, and the matter field, the
periodic
liquid crystal medium, at the edge of the photonic band
gap. In this thesis, several tunable
liquid crystal laser systems
are investigated: cholesteric
liquid crystals, holographic-polymer
dispersed
liquid crystals and
liquid crystal polarization gratings.
The primary focus has been to fabricate systems that are tunable
through electrical means, as applications requiring mechanical or
thermal changes are often difficult to control. Cholesteric
liquid
crystal lasers are helical Bragg reflectors, with a band gap for
circularly polarized light of equivalent handedness to their helix.
These materials were doped with a laser dye and laser emission was
observed. The use of an in-plane electric field tends to unwind the
helical pitch of the film and in doing so tunable emission was
demonstrated for ~15 nm. Holographic-polymer dispersed
liquid
crystals (H-PDLCs) are grating structures consisting of alternating
layers of polymer and
liquid crystal, with different indices of
refraction. The application of an electric field index matches
these layers and `switches off' the grating. Thus, laser emission
can be switched on and off through the use of an electric field.
Spatially tunable H-PDLC lasers were fabricated by creating chirped
gratings, formed by divergent beams. The emission was shown to tune
~5 nm as the pump beam was translated across a 1 inch film.
Liquid
crystal polarization gratings use photo-patterned alignment layers,
through a polarization holography exposure, to induce an alignment
in a
liquid crystal film. Electrically tunable emission was
demonstrated in these systems. Applications of
liquid crystal
lasers include emissive substrates or backplanes for displays or
tunable emission sources for biology and medicine. The potential
for such applications are discussed.
Advisors/Committee Members: Crawford, Gregory (director), Pelcovits, Robert (reader), Valles, James (reader).
Subjects/Keywords: Liquid crystals
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APA ·
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APA (6th Edition):
Woltman, S. J. (2008). Tunable liquid crystal lasers. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:186/
Chicago Manual of Style (16th Edition):
Woltman, Scott Jeffrey. “Tunable liquid crystal lasers.” 2008. Doctoral Dissertation, Brown University. Accessed March 02, 2021.
https://repository.library.brown.edu/studio/item/bdr:186/.
MLA Handbook (7th Edition):
Woltman, Scott Jeffrey. “Tunable liquid crystal lasers.” 2008. Web. 02 Mar 2021.
Vancouver:
Woltman SJ. Tunable liquid crystal lasers. [Internet] [Doctoral dissertation]. Brown University; 2008. [cited 2021 Mar 02].
Available from: https://repository.library.brown.edu/studio/item/bdr:186/.
Council of Science Editors:
Woltman SJ. Tunable liquid crystal lasers. [Doctoral Dissertation]. Brown University; 2008. Available from: https://repository.library.brown.edu/studio/item/bdr:186/
12.
Jaiswal, Ashok Kumar.
Studies on Liquid crystals; -.
Degree: Physics, 1980, Pt. Ravishankar Shukla University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/43732
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Jaiswal, A. K. (1980). Studies on Liquid crystals; -. (Thesis). Pt. Ravishankar Shukla University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/43732
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Jaiswal, Ashok Kumar. “Studies on Liquid crystals; -.” 1980. Thesis, Pt. Ravishankar Shukla University. Accessed March 02, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/43732.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Jaiswal, Ashok Kumar. “Studies on Liquid crystals; -.” 1980. Web. 02 Mar 2021.
Vancouver:
Jaiswal AK. Studies on Liquid crystals; -. [Internet] [Thesis]. Pt. Ravishankar Shukla University; 1980. [cited 2021 Mar 02].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/43732.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Jaiswal AK. Studies on Liquid crystals; -. [Thesis]. Pt. Ravishankar Shukla University; 1980. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/43732
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Oregon State University
13.
Kelley, Thomas E.
Microcontinuum theory and orientational effects in smectic liquid crystals.
Degree: PhD, Mathematics, 1977, Oregon State University
URL: http://hdl.handle.net/1957/17576
► Micropolar Theory, a specialization of the Microcontinuum Theory advanced by A. C. Eringen in the early 1960ts has been used successfully in predicting the behavior…
(more)
▼ Micropolar Theory, a specialization of the Microcontinuum
Theory advanced by A. C. Eringen in the early 1960ts has been
used successfully in predicting the behavior of materials whose
inner structure is composed of rod-like elements.
Liquid crystals
fall into this class of materials and their wide-spread use in
Industry and in medical diagnostic devices requires a detailed
analysis of their response to various external stimuli. To this
end we have undertaken a detailed study of smectic
liquid crystals
using the micropolar theory.
The first step was to develop a mathematical foundation for
irreversible and nonlinear thermodynamics of
liquid crystals and
mathematical methods for obtaining thermodynamical restrictions
on the material response coefficients of smectic
liquid crystals. Full symmetry properties of
liquid crystals have been employed in
order to simplify the constitutive equations.
This theory has then been applied to the physical problem of
predicting orientational effects in smectic
liquid crystals due to
boundary influences, superposed shear flows, and thermal gradients.
Since most experiments are carried out for viscometric flows we
have considered the flow of smectic
liquid crystals between two
rotating coaxial cylinders. The velocity field obtained is found to
include the classical Couette flow as a special case. We then compare
our results with experiments and identify the material
coefficients of the theory with physically measurable quantities such
as apparent viscosity. The shear-rate dependence of viscosity at
various temperatures of the srnectic range is determined and
comparisons with experimental results yield good agreement.
Finally, with the aim of constructing a viscoelastic theory
suitable for description of materials with stretchable rod-like
elements we first develop the theory of micropolar elasticity with
stretch which takes into account the uniform stretching of the
material's microelements. Future work involving the construction
of the theory of micropolar viscoelasticity with stretch and its
application to the study of viscoelastic waves is indicated.
Advisors/Committee Members: Narasimhan, M. N. L. (advisor).
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Kelley, T. E. (1977). Microcontinuum theory and orientational effects in smectic liquid crystals. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/17576
Chicago Manual of Style (16th Edition):
Kelley, Thomas E. “Microcontinuum theory and orientational effects in smectic liquid crystals.” 1977. Doctoral Dissertation, Oregon State University. Accessed March 02, 2021.
http://hdl.handle.net/1957/17576.
MLA Handbook (7th Edition):
Kelley, Thomas E. “Microcontinuum theory and orientational effects in smectic liquid crystals.” 1977. Web. 02 Mar 2021.
Vancouver:
Kelley TE. Microcontinuum theory and orientational effects in smectic liquid crystals. [Internet] [Doctoral dissertation]. Oregon State University; 1977. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/1957/17576.
Council of Science Editors:
Kelley TE. Microcontinuum theory and orientational effects in smectic liquid crystals. [Doctoral Dissertation]. Oregon State University; 1977. Available from: http://hdl.handle.net/1957/17576
Hong Kong University of Science and Technology
14.
Zhang, Baoshe.
A study of substrate – liquid crystal interaction.
Degree: 2003, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-610
;
https://doi.org/10.14711/thesis-b785672
;
http://repository.ust.hk/ir/bitstream/1783.1-610/1/th_redirect.html
► This thesis concerns the study of substrate-liquid crystal interaction from two different angles. In one approach, we used the IPS (in-plane switching) technique to investigate…
(more)
▼ This thesis concerns the study of substrate-liquid crystal interaction from two different angles. In one approach, we used the IPS (in-plane switching) technique to investigate the liquid crystal alignment by rubbed polyimide films. The IPS mode of liquid crystal cell operation is facilitated through comb electrodes capable of producing planar electric field. We have fabricated comb electrodes with a periodicity of 2 μm in order to confine the planar electric field close to the liquid crystal-substrate interface. Through optical transmittance measurements and comparison with theoretical predictions based on the Ladau-de Gennes formalism, we found the experimental data to be consistent with the physical picture of soft anchoring, in which the liquid crystal director at the substrate interface is rotated azimuthally under the planar electric field. As a result, we were able to obtain the azimuthal anchoring strength as a fitting parameter of the theory. This part of the thesis thus presents evidence(s) for director switching at the liquid crystal-substrate interface, as well as a method for measuring the azimuthal anchoring strength through optical means. In the second approach, we used nano-lithographic technique to fabricate textured two dimensional periodic patterns on silicon wafers, and examined the resulting liquid crystal alignment effect of such textured substrates. It was found that with decreasing periodicity, there exists an orientational transition from a state in which the liquid crystal alignment copies the substrate pattern at larger periodicity, to a state of uniform alignment at smaller periodicity. In our system, this transition occurs at a periodicity between 0.4 μm and 0.8 μm . Through theoretical simulations based on the model of competition between the elastic distortion energy and the interfacial anchoring potential, it was found that there is indeed a first-order abrupt transition when the periodicity is decreased. This is due to the fact that the elastic distortion energy scales as the inverse of the periodicity squared. Hence when the periodicity is decreased, the elastic distortion energy increases rapidly. At the critical periodicity the elastic distortion energy crosses the interfacial anchoring potential, below which the uniform alignment becomes the lower energy state. The uniform-aligned state was confirmed by the excellent theory-experiment agreement on spectral measurements, in conjuction with the optical microscope observations. In the uniform-aligned state, a large pretilt angle (35°) was obtained.
Subjects/Keywords: Liquid crystals
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MLA ·
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APA (6th Edition):
Zhang, B. (2003). A study of substrate – liquid crystal interaction. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-610 ; https://doi.org/10.14711/thesis-b785672 ; http://repository.ust.hk/ir/bitstream/1783.1-610/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zhang, Baoshe. “A study of substrate – liquid crystal interaction.” 2003. Thesis, Hong Kong University of Science and Technology. Accessed March 02, 2021.
http://repository.ust.hk/ir/Record/1783.1-610 ; https://doi.org/10.14711/thesis-b785672 ; http://repository.ust.hk/ir/bitstream/1783.1-610/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zhang, Baoshe. “A study of substrate – liquid crystal interaction.” 2003. Web. 02 Mar 2021.
Vancouver:
Zhang B. A study of substrate – liquid crystal interaction. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2003. [cited 2021 Mar 02].
Available from: http://repository.ust.hk/ir/Record/1783.1-610 ; https://doi.org/10.14711/thesis-b785672 ; http://repository.ust.hk/ir/bitstream/1783.1-610/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Zhang B. A study of substrate – liquid crystal interaction. [Thesis]. Hong Kong University of Science and Technology; 2003. Available from: http://repository.ust.hk/ir/Record/1783.1-610 ; https://doi.org/10.14711/thesis-b785672 ; http://repository.ust.hk/ir/bitstream/1783.1-610/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Debrecen
15.
Abdollahzadeh, Aysen.
Pharmaceutical Description Of Liquid Crystals
.
Degree: DE – Gyógyszerésztudományi Kar, University of Debrecen
URL: http://hdl.handle.net/2437/240866
► nowadays much interest has been focused on lipid based formulations,with particular emphasis on semi solid liquid crystals as a possible drug delivery system to improve…
(more)
▼ nowadays much interest has been focused on lipid based formulations,with particular emphasis on semi solid
liquid crystals as a possible drug delivery system to improve the bioavailibility of poorly soluble drugs.the aim of this pharmD thesis work was to demonstrate this novel dosage forms from pharmaceutical stand point.the theoretical background of lipid API carriers had been described according to the relevant literature.formulation techniques had been presented according to the guideline of Gattefosse chemical company suggesstions.in addition to a detailed look at the technical aspects of
liquid crystal formulation.this collection of theoretical and technical information and instruction might ensure useful data for pharmacon loaded
liquid crystal formulation by suggesting different lipid compositions to reach better bioavailibility and compliance.
Advisors/Committee Members: Ujhelyi, Zoltán (advisor), Debreceni Egyetem::Gyógyszerésztudományi Kar (advisor).
Subjects/Keywords: liquid crystals
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APA (6th Edition):
Abdollahzadeh, A. (n.d.). Pharmaceutical Description Of Liquid Crystals
. (Thesis). University of Debrecen. Retrieved from http://hdl.handle.net/2437/240866
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Abdollahzadeh, Aysen. “Pharmaceutical Description Of Liquid Crystals
.” Thesis, University of Debrecen. Accessed March 02, 2021.
http://hdl.handle.net/2437/240866.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Abdollahzadeh, Aysen. “Pharmaceutical Description Of Liquid Crystals
.” Web. 02 Mar 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Abdollahzadeh A. Pharmaceutical Description Of Liquid Crystals
. [Internet] [Thesis]. University of Debrecen; [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2437/240866.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
No year of publication.
Council of Science Editors:
Abdollahzadeh A. Pharmaceutical Description Of Liquid Crystals
. [Thesis]. University of Debrecen; Available from: http://hdl.handle.net/2437/240866
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
No year of publication.
Montana State University
16.
Himmer, Phillip Alexander.
Freedericksz transitions in nematic liquid crystal.
Degree: MS, College of Letters & Science, 1992, Montana State University
URL: https://scholarworks.montana.edu/xmlui/handle/1/7104
Subjects/Keywords: Liquid crystals.
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APA (6th Edition):
Himmer, P. A. (1992). Freedericksz transitions in nematic liquid crystal. (Masters Thesis). Montana State University. Retrieved from https://scholarworks.montana.edu/xmlui/handle/1/7104
Chicago Manual of Style (16th Edition):
Himmer, Phillip Alexander. “Freedericksz transitions in nematic liquid crystal.” 1992. Masters Thesis, Montana State University. Accessed March 02, 2021.
https://scholarworks.montana.edu/xmlui/handle/1/7104.
MLA Handbook (7th Edition):
Himmer, Phillip Alexander. “Freedericksz transitions in nematic liquid crystal.” 1992. Web. 02 Mar 2021.
Vancouver:
Himmer PA. Freedericksz transitions in nematic liquid crystal. [Internet] [Masters thesis]. Montana State University; 1992. [cited 2021 Mar 02].
Available from: https://scholarworks.montana.edu/xmlui/handle/1/7104.
Council of Science Editors:
Himmer PA. Freedericksz transitions in nematic liquid crystal. [Masters Thesis]. Montana State University; 1992. Available from: https://scholarworks.montana.edu/xmlui/handle/1/7104
Montana State University
17.
Huang, Wei.
Structure and shape of nematic liquid crystal microdroplets.
Degree: MS, College of Letters & Science, 1993, Montana State University
URL: https://scholarworks.montana.edu/xmlui/handle/1/6736
Subjects/Keywords: Liquid crystals.
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APA (6th Edition):
Huang, W. (1993). Structure and shape of nematic liquid crystal microdroplets. (Masters Thesis). Montana State University. Retrieved from https://scholarworks.montana.edu/xmlui/handle/1/6736
Chicago Manual of Style (16th Edition):
Huang, Wei. “Structure and shape of nematic liquid crystal microdroplets.” 1993. Masters Thesis, Montana State University. Accessed March 02, 2021.
https://scholarworks.montana.edu/xmlui/handle/1/6736.
MLA Handbook (7th Edition):
Huang, Wei. “Structure and shape of nematic liquid crystal microdroplets.” 1993. Web. 02 Mar 2021.
Vancouver:
Huang W. Structure and shape of nematic liquid crystal microdroplets. [Internet] [Masters thesis]. Montana State University; 1993. [cited 2021 Mar 02].
Available from: https://scholarworks.montana.edu/xmlui/handle/1/6736.
Council of Science Editors:
Huang W. Structure and shape of nematic liquid crystal microdroplets. [Masters Thesis]. Montana State University; 1993. Available from: https://scholarworks.montana.edu/xmlui/handle/1/6736
University of New Mexico
18.
Doyle, Derek.
Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space.
Degree: Electrical and Computer Engineering, 2016, University of New Mexico
URL: http://hdl.handle.net/1928/31715
► The space industry has predominantly relied on high gain reflector dish antenna apertures for performing communications, but is constantly investing in phase array antenna concepts…
(more)
▼ The space industry has predominantly relied on high gain reflector dish antenna apertures for performing communications, but is constantly investing in phase array antenna concepts to provide increased signal flexibility at reduced system costs in terms of finances and system resources. The problem with traditional phased arrays remains the significantly greater program cost and complexity added to the satellite by integrating arrays of antenna elements with dedicated amplifier and phase shifters to perform adaptive beam forming.
Liquid Crystal Reflectarrays (LiCRas) offer some of the electrical beam forming capability of a phased array system with the component and design complexity in lines with a traditional reflector antenna aperture but without the risks associated with mechanical steering systems. The final solution is believed to be a hybrid approach that performs in between the boundaries set by the two current disparate approaches. Practical reflectarrays have been developed since the 90s as a means to control reflection of incident radiation off a flat structure that is electrically curved based on radiating elements and their reflection characteristics with tailored element phase delay. In the last decade several methods have been proposed to enable tunable reflectarrays where the electrical shape of the reflector can be steered by controlling the resonating properties of the elements on the reflector using a DC bias. These approaches range from complex fast switching MEMS and ferroelectric devices, to more robust but slower chemical changes. The aim of this work is to investigate the feasibility of a molecular transition approach in the form of
liquid crystals which change permittivity based on the electrical field they are subjected to. In this work, particular attention will be paid to the impact of space environment on
liquid crystal reflectarray materials and reflector architectures. Of particular interest are the effects on performance induced by the temperature extremes of space and the electromagnetic particle environment. These two items tend to drive much of the research and development for various space technologies and based on these physical influences, assertions can be made toward the space worthiness of such a material approach and can layout future R&D needs to make certain LC RF devices feasible for space use. Moreover, in this work the performance metrics of such a technology will be addressed along with methods of construction from a space perspective where specific design considerations must be made based on the extreme environment that a typical space asset must endure.'
Advisors/Committee Members: Christodoulou, Christos, Gilmore, Mark, Khraishi, Tariq, Arritt, Brandon.
Subjects/Keywords: Liquid Crystals; Space; antenna
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APA (6th Edition):
Doyle, D. (2016). Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space. (Doctoral Dissertation). University of New Mexico. Retrieved from http://hdl.handle.net/1928/31715
Chicago Manual of Style (16th Edition):
Doyle, Derek. “Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space.” 2016. Doctoral Dissertation, University of New Mexico. Accessed March 02, 2021.
http://hdl.handle.net/1928/31715.
MLA Handbook (7th Edition):
Doyle, Derek. “Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space.” 2016. Web. 02 Mar 2021.
Vancouver:
Doyle D. Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space. [Internet] [Doctoral dissertation]. University of New Mexico; 2016. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/1928/31715.
Council of Science Editors:
Doyle D. Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space. [Doctoral Dissertation]. University of New Mexico; 2016. Available from: http://hdl.handle.net/1928/31715
University of Minnesota
19.
Hiltner, Lindsey.
Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology.
Degree: PhD, Mathematics, 2018, University of Minnesota
URL: http://hdl.handle.net/11299/202192
► Using the mathematical theory of liquid crystals, we propose models for equilibrium configurations of the hexagonal columnar phase of lyotropic chromonic liquid crystals (LCLCs). These…
(more)
▼ Using the mathematical theory of liquid crystals, we propose models for equilibrium configurations of the hexagonal columnar phase of lyotropic chromonic liquid crystals (LCLCs). These models are applied in a collection of settings in which the underlying phases are naturally observed, including LCLC toroidal superstructures, liquid crystal confined to a thin capillary, double-stranded DNA packed in bacteriophage viruses, and DNA toroidal clusters that form in the presence of condensing agents. Although the length scale of these superstructures ranges from nanometers to microns, they show the ability to sustain pressures of up to 60 atmospheres. In each setting, we investigate equilibrium configurations and discuss well-posedness of our model. The mathematical work focuses in the analysis of constrained free boundary problems for combined liquid crystal and elastic energies, with a main focus on the very rich structure of defect cores in lyotropic systems. We conclude with potential modifications to the model that could be used to incorporate information such as ionic concentrations present in the medium surrounding this liquid crystal phase.
Subjects/Keywords: Bacteriophage; Chromonic; Liquid Crystals
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APA (6th Edition):
Hiltner, L. (2018). Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/202192
Chicago Manual of Style (16th Edition):
Hiltner, Lindsey. “Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology.” 2018. Doctoral Dissertation, University of Minnesota. Accessed March 02, 2021.
http://hdl.handle.net/11299/202192.
MLA Handbook (7th Edition):
Hiltner, Lindsey. “Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology.” 2018. Web. 02 Mar 2021.
Vancouver:
Hiltner L. Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology. [Internet] [Doctoral dissertation]. University of Minnesota; 2018. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/11299/202192.
Council of Science Editors:
Hiltner L. Equilibrium Configurations of Hexagonal Columnar Liquid Crystals with Applications to Materials Science and Biology. [Doctoral Dissertation]. University of Minnesota; 2018. Available from: http://hdl.handle.net/11299/202192
University of British Columbia
20.
Palffy-Muhoray, Peter.
Refractive indices of liquid crystals and pure fluids near phase transitions.
Degree: PhD, Physics, 1977, University of British Columbia
URL: http://hdl.handle.net/2429/20911
► Interferometric measurements to determine the refractive indices of the nematic liquid crystals EBBA and BEPC as a function of temperature are described utilizing modified Rayleigh…
(more)
▼ Interferometric measurements to determine the refractive indices
of the nematic liquid crystals EBBA and BEPC as a function of temperature are described utilizing modified Rayleigh and conoscopic interferometers. Theory is presented relating the refractive indices and density to the orientational order, local field parameter and molecular
properties. The results of simple thermal expansivity measurements
are also given for EBBA.
The Lorentz-Lorenz coefficient for SF₆, and GeH₄, has been
determined from refractive index and density measurements. The method
utilizes a prism shaped high pressure cell which can be removed from
a temperature controlled holder and weighed on a precision balance.
The results indicate a variation of 0.5% for SF₆, and 0.8% for GeH₄,
over the density range covered.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Palffy-Muhoray, P. (1977). Refractive indices of liquid crystals and pure fluids near phase transitions. (Doctoral Dissertation). University of British Columbia. Retrieved from http://hdl.handle.net/2429/20911
Chicago Manual of Style (16th Edition):
Palffy-Muhoray, Peter. “Refractive indices of liquid crystals and pure fluids near phase transitions.” 1977. Doctoral Dissertation, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/20911.
MLA Handbook (7th Edition):
Palffy-Muhoray, Peter. “Refractive indices of liquid crystals and pure fluids near phase transitions.” 1977. Web. 02 Mar 2021.
Vancouver:
Palffy-Muhoray P. Refractive indices of liquid crystals and pure fluids near phase transitions. [Internet] [Doctoral dissertation]. University of British Columbia; 1977. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/20911.
Council of Science Editors:
Palffy-Muhoray P. Refractive indices of liquid crystals and pure fluids near phase transitions. [Doctoral Dissertation]. University of British Columbia; 1977. Available from: http://hdl.handle.net/2429/20911
University of British Columbia
21.
Wang, Xin.
1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder.
Degree: MS- MSc, Chemistry, 1987, University of British Columbia
URL: http://hdl.handle.net/2429/28353
► New liquid crystals have been synthesized and their transition phases have been studied. It was found that a family of (-)-2-methyl 2R,3S-epithio-4'-alkoxybiphenyl pentanoates are liquid…
(more)
▼ New liquid crystals have been synthesized and their transition phases have been studied. It was found that a family of (-)-2-methyl 2R,3S-epithio-4'-alkoxybiphenyl pentanoates are liquid crystals but a similar system of ( + )-2-methyl 2S,3R-epoxy-4'-alkoxybiphenyl pentanoates are not. Of the liquid crystals, MEAOBP-S-7 exhibits smectic A and B phases; MEAOBP-S-8 and MEAOBP-S-9 show only the smectic B phases; MEAOBP-S-10 shows a monotropic chiral smectic C phase. This distinction is in agreement with the argument that the internal dipolar interaction of the molecule plays an important role in determining liquid crystalline behaviour of this ester system.
The reaction rate of the racemization of optically active binaphthyl can be moderately increased in the presence of finely divided titanium dioxide (anatase) powder. This first order catalyzed reaction has a proportional relationship with the concentrations of both the catalyst and the binaphthyl.
The catalyzed reaction can be poisoned permanently by the addition of polynuclear aromatic compounds and the poisoning efficiency is dependent of the number of the aromatic rings the poison posesses. By comparison with the catalyzed racemizations of binaphthyl by platinum, nickel and carbon and from the kinetic and mechanistic studies on the titanium dioxide catalyzed racemization, we conclude that (1) this catalytic phenomenon is common among heterogeneous inorganic solids and can be extended to other simple reactions, and that (2) the mechanism of the catalysis probably involves a radical anion intermediate.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Wang, X. (1987). 1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder. (Masters Thesis). University of British Columbia. Retrieved from http://hdl.handle.net/2429/28353
Chicago Manual of Style (16th Edition):
Wang, Xin. “1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder.” 1987. Masters Thesis, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/28353.
MLA Handbook (7th Edition):
Wang, Xin. “1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder.” 1987. Web. 02 Mar 2021.
Vancouver:
Wang X. 1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder. [Internet] [Masters thesis]. University of British Columbia; 1987. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/28353.
Council of Science Editors:
Wang X. 1. Design and synthesis of new chiral units for potentially ferroelectric liquid crystals : liquid crystals containing a thiiran unit. 2. Heterogeneous catalysis of the racemization of 1,1'-binaphthyl by titanium dioxide powder. [Masters Thesis]. University of British Columbia; 1987. Available from: http://hdl.handle.net/2429/28353
University of British Columbia
22.
MacKay, Alexander Lloyd.
An EPR study of order and molecular orientation in liquid crystals.
Degree: MS- MSc, Physics, 1971, University of British Columbia
URL: http://hdl.handle.net/2429/34162
► Using EPR, the temperature dependence of the effective order parameter of the molecule vanadyl acetylacetonate in the nematic liquid crystal 4-methoxy benzylidene-n-butyl aniline was studied.…
(more)
▼ Using EPR, the temperature dependence of the effective order parameter of the molecule vanadyl acetylacetonate in the nematic liquid crystal 4-methoxy benzylidene-n-butyl aniline was studied. In the resulting data, a discontinuity in slope of the curve of effective order parameter versus temperature was found, indicating a change to a more restricted type of motion at lower temperatures. Similar results were obtained from NMR T₁ measurements on the pure liquid crystal. The discontinuity cannot be interpreted solely as a viscosity effect.
Two cholesteric liquid crystal mixtures containing vanadyl acetylacetonate were subjected to a high magnetic field (~20 kilogauss). Prom EPR measurements, a 1.75:1 mixture by weight of cholesteryl chloride and cholesteryl myristate was found to orient its helix axis parallel to the field direction. In a.2 percent by weight mixture of cholesteryl chloride in nematic 4-methoxy benzylidene-n-butyl aniline, the molecules tended to arrange their long axes parallel to the field thus making the helix axis perpendicular to the field.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
MacKay, A. L. (1971). An EPR study of order and molecular orientation in liquid crystals. (Masters Thesis). University of British Columbia. Retrieved from http://hdl.handle.net/2429/34162
Chicago Manual of Style (16th Edition):
MacKay, Alexander Lloyd. “An EPR study of order and molecular orientation in liquid crystals.” 1971. Masters Thesis, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/34162.
MLA Handbook (7th Edition):
MacKay, Alexander Lloyd. “An EPR study of order and molecular orientation in liquid crystals.” 1971. Web. 02 Mar 2021.
Vancouver:
MacKay AL. An EPR study of order and molecular orientation in liquid crystals. [Internet] [Masters thesis]. University of British Columbia; 1971. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/34162.
Council of Science Editors:
MacKay AL. An EPR study of order and molecular orientation in liquid crystals. [Masters Thesis]. University of British Columbia; 1971. Available from: http://hdl.handle.net/2429/34162
University of British Columbia
23.
Gleeson, James Theodore.
Surface anchoring of nematic liquid crystals.
Degree: MS- MSc, Physics, 1988, University of British Columbia
URL: http://hdl.handle.net/2429/27928
► The surface anchoring of the nematic liquid crystal 5CB aligned tangentially on two different glass substrate treatments is studied. These two treatments are obliquely evaporated…
(more)
▼ The surface anchoring of the nematic liquid crystal 5CB aligned tangentially on two different glass substrate treatments is studied. These two treatments are obliquely evaporated SiO and buffed poly(vinyl formal) deposited from solution. The latter is believed to be a new treatment and of possible importance to the twisted nematic liquid crystal display industry.
Two methods are employed to measure the strength of the surface anchoring potential. The first was originally developed by Yokoyama and van Sprang, and yields the coefficient of the Rapini-Papoular anchoring potential. The second is a new method based on the Frank-Oseen elasticity theory. It is an extension of Deuling's 1972 solution of the splay Freedericksz transition. The second yields the functional form of the anchoring potential.
Both methods are based on measurements of the bulk dielectric constant and the effective refractive index of a nematic sample that has undergone a splay Freedericksz transition. The first method requires both these measurements, and the second requires one or the other; both can be employed as a verification of results. The latter method is found to be very sensitive to the value of the dielectric anisotropy; this is believed to be due to not allowing for spatial variations in the scalar order parameter.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Gleeson, J. T. (1988). Surface anchoring of nematic liquid crystals. (Masters Thesis). University of British Columbia. Retrieved from http://hdl.handle.net/2429/27928
Chicago Manual of Style (16th Edition):
Gleeson, James Theodore. “Surface anchoring of nematic liquid crystals.” 1988. Masters Thesis, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/27928.
MLA Handbook (7th Edition):
Gleeson, James Theodore. “Surface anchoring of nematic liquid crystals.” 1988. Web. 02 Mar 2021.
Vancouver:
Gleeson JT. Surface anchoring of nematic liquid crystals. [Internet] [Masters thesis]. University of British Columbia; 1988. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/27928.
Council of Science Editors:
Gleeson JT. Surface anchoring of nematic liquid crystals. [Masters Thesis]. University of British Columbia; 1988. Available from: http://hdl.handle.net/2429/27928
University of British Columbia
24.
Gingras, Michel.
Nonseparable interactions and orientational phenomena in liquid crystals.
Degree: PhD, Physics, 1990, University of British Columbia
URL: http://hdl.handle.net/2429/30582
► Intermolecular interactions are anisotropic since they depend on the orientations of the interacting molecules. They are responsible for the orientational phase transitions observed in molecular…
(more)
▼ Intermolecular interactions are anisotropic since they depend on the orientations of the interacting molecules. They are responsible for the orientational phase transitions observed
in molecular systems. The effects of nonseparable interactions, which depend on both the molecular and intermolecular vector orientations, are investigated using Monte-Carlo simulations. It is found that for systems with quenched positional disorder, the nonseparability of the pair potential leads to orientational frustration. Expanding the pair potential in terms of its rotational invariants allows one to isolate random field terms whose presence are shown to be at the origin of the non-frustrated patches observed in such disordered systems.
For liquid crystals, where translational and rotational degrees of freedom are in thermal
equilibrium, Monte-Carlo results show that an ordering of the molecular orientations induces an ordering of the nearest-neighbor bond orientations only when the pair potential
is nonseparable. These results suggest that it is necessary to reinterpret the mean-field theory of nematic liquid crystals as an approximation which neglects the presence of bond ordering in these systems. As well, they unravel the microscopic origin of the phenomeno-logical coupling between bond and molecular orientations invoked in Ginzburg-Landau theories of liquid crystals.
The nonseparability of the intermolecular pair potential leads to a coupling between the nearest-neighbor bond orientational field and the molecular orientational field. It is shown that such coupling introduces new and interesting effects in liquid crystalline systems where interactions between the molecular and nearest-neighbor bond orientations are usually ignored.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Gingras, M. (1990). Nonseparable interactions and orientational phenomena in liquid crystals. (Doctoral Dissertation). University of British Columbia. Retrieved from http://hdl.handle.net/2429/30582
Chicago Manual of Style (16th Edition):
Gingras, Michel. “Nonseparable interactions and orientational phenomena in liquid crystals.” 1990. Doctoral Dissertation, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/30582.
MLA Handbook (7th Edition):
Gingras, Michel. “Nonseparable interactions and orientational phenomena in liquid crystals.” 1990. Web. 02 Mar 2021.
Vancouver:
Gingras M. Nonseparable interactions and orientational phenomena in liquid crystals. [Internet] [Doctoral dissertation]. University of British Columbia; 1990. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/30582.
Council of Science Editors:
Gingras M. Nonseparable interactions and orientational phenomena in liquid crystals. [Doctoral Dissertation]. University of British Columbia; 1990. Available from: http://hdl.handle.net/2429/30582
University of British Columbia
25.
Morris, Stephen William.
Measurements of the elastic constants of a liquid crystal.
Degree: MS- MSc, Physics, 1985, University of British Columbia
URL: http://hdl.handle.net/2429/24869
► The bend and splay elastic constants of the nematic liquid crystal octylcyanobiphenyl (8CB) are measured as a function of temperature using an electric-field-induced deformation. The…
(more)
▼ The bend and splay elastic constants of the nematic liquid crystal octylcyanobiphenyl (8CB) are measured as a function of temperature using an electric-field-induced deformation.
The capacitance and birefringence of a sample cell, temperature controlled to 0.1mK, were simultaneously measured as a function of applied voltage. The splay constant is determined from the critical voltage at the onset of the deformation (the Freedericksz transition). The bend constant is found by fitting the data above the critical voltage to the theory of Deuling, which is derived in full. The data is also analysed in the high- and low-field limits of the theory.
The bend elastic constant displays a pretransitional divergence near the nematic-smectic A phase transition due to smectic fluctuation effects. The divergent part is fit by a power law with a critical exponent of 1.0±0.1.
The Deuling theory, which is based on the assumption of linear elasticity, shows systematic deviation from the data at high voltages at all temperatures, with the disagreement increasing rapidly as the smectic phase is approached.
This result suggests that the linear elastic theory of Dueling/ fails for large deformations and where smectic fluctuations contribute signifigantly to the bend elasticity. The failure near the smectic transition may be explainable by the quenching of smectic fluctuations by the deformation.
Subjects/Keywords: Liquid crystals
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APA (6th Edition):
Morris, S. W. (1985). Measurements of the elastic constants of a liquid crystal. (Masters Thesis). University of British Columbia. Retrieved from http://hdl.handle.net/2429/24869
Chicago Manual of Style (16th Edition):
Morris, Stephen William. “Measurements of the elastic constants of a liquid crystal.” 1985. Masters Thesis, University of British Columbia. Accessed March 02, 2021.
http://hdl.handle.net/2429/24869.
MLA Handbook (7th Edition):
Morris, Stephen William. “Measurements of the elastic constants of a liquid crystal.” 1985. Web. 02 Mar 2021.
Vancouver:
Morris SW. Measurements of the elastic constants of a liquid crystal. [Internet] [Masters thesis]. University of British Columbia; 1985. [cited 2021 Mar 02].
Available from: http://hdl.handle.net/2429/24869.
Council of Science Editors:
Morris SW. Measurements of the elastic constants of a liquid crystal. [Masters Thesis]. University of British Columbia; 1985. Available from: http://hdl.handle.net/2429/24869
Simon Fraser University
26.
Tamblyn, Nancy A.
Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point.
Degree: 1994, Simon Fraser University
URL: http://summit.sfu.ca/item/5125
Subjects/Keywords: Liquid crystals.
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APA (6th Edition):
Tamblyn, N. A. (1994). Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point. (Thesis). Simon Fraser University. Retrieved from http://summit.sfu.ca/item/5125
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Tamblyn, Nancy A. “Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point.” 1994. Thesis, Simon Fraser University. Accessed March 02, 2021.
http://summit.sfu.ca/item/5125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Tamblyn, Nancy A. “Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point.” 1994. Web. 02 Mar 2021.
Vancouver:
Tamblyn NA. Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point. [Internet] [Thesis]. Simon Fraser University; 1994. [cited 2021 Mar 02].
Available from: http://summit.sfu.ca/item/5125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Tamblyn NA. Is the nematic-smectic A transition always first order? : measurements of surface tension near an apparent tricritical point. [Thesis]. Simon Fraser University; 1994. Available from: http://summit.sfu.ca/item/5125
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Aberdeen
27.
Walker, Rebecca.
Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase.
Degree: PhD, 2019, University of Aberdeen
URL: https://abdn.alma.exlibrisgroup.com/view/delivery/44ABE_INST/12152801350005941
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767357
► The principal aim of this Thesis is the synthesis and characterisation of a range of novel liquid crystals designed to exhibit the twist-bend nematic phase…
(more)
▼ The principal aim of this Thesis is the synthesis and characterisation of a range of novel liquid crystals designed to exhibit the twist-bend nematic phase (NTB), in order to enhance our understanding of the relationships between molecular structure and the observation of NTB behaviour. Moreover, the inclusion of chiral fragments allowed the effects of molecular chirality on the structure of the NTB phase, specifically the chiral twist-bend nematic phase, N*TB, to be studied. In Chapter 3, a series of non-symmetric odd-membered liquid crystal dimers are prepared and the terminal chain length m is varied. A change in the local molecular structure from intercalated to bilayer is seen on increasing m, but this has no apparent effect on the stability of both the nematic and twist-bend nematic phases, which show a regular dependence on m. A novel twist-bend smectic phase is reported. Chapter 4 investigates the effects of branching this terminal chain on phase behaviour. It is evident that in dimers with a shorter spacer, branching destabilises the N and NTB phases while stabilising smectic behaviour, but in longer homologues smectic behaviour is also destabilised. Chapter 5 explores the effect of molecular bulk on phase behaviour, specifically the stability of the NTB phase, by the incorporation of a pyrene moiety. This group supresses crystallisation such that stable, low temperature NTB phases are formed despite the bulky group. Chapters 6 and 7 study the inclusion of chiral moieties in bent-shaped, odd-membered dimers: specifically, 2-methylbutyl, 1-methylheptyl (6) and lactic esters (7). New examples of the rarely observed chiral twist-bend nematic phase are seen. Phase behaviour is investigated and compared to achiral and racemic analogues. Chapter 8 describes the mesogenic behaviour of molecular complexes assembled by hydrogen bonding between both achiral and chiral stilbazole-based and benzoic acid-based fragments. A selection of the complexes exhibit the N(*)TB phase despite only one or neither component being mesogenic.
Subjects/Keywords: 530.4; Liquid crystals; Chirality; Dimers
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APA (6th Edition):
Walker, R. (2019). Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase. (Doctoral Dissertation). University of Aberdeen. Retrieved from https://abdn.alma.exlibrisgroup.com/view/delivery/44ABE_INST/12152801350005941 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767357
Chicago Manual of Style (16th Edition):
Walker, Rebecca. “Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase.” 2019. Doctoral Dissertation, University of Aberdeen. Accessed March 02, 2021.
https://abdn.alma.exlibrisgroup.com/view/delivery/44ABE_INST/12152801350005941 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767357.
MLA Handbook (7th Edition):
Walker, Rebecca. “Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase.” 2019. Web. 02 Mar 2021.
Vancouver:
Walker R. Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase. [Internet] [Doctoral dissertation]. University of Aberdeen; 2019. [cited 2021 Mar 02].
Available from: https://abdn.alma.exlibrisgroup.com/view/delivery/44ABE_INST/12152801350005941 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767357.
Council of Science Editors:
Walker R. Synthesis and characterisation of novel liquid crystalline materials : structure-property relationships, chirality, and the twist-bend nematic phase. [Doctoral Dissertation]. University of Aberdeen; 2019. Available from: https://abdn.alma.exlibrisgroup.com/view/delivery/44ABE_INST/12152801350005941 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767357
Hong Kong University of Science and Technology
28.
Tseng, Man Chun ECE.
Novel alignment surfaces for liquid crystal display.
Degree: 2016, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-89664
;
https://doi.org/10.14711/thesis-b1584831
;
http://repository.ust.hk/ir/bitstream/1783.1-89664/1/th_redirect.html
► Thought brushed polyimide is commercially widely used in LCD production there are many problems associated with mechanical rubbing; dust acting as nucleation seeds is one.…
(more)
▼ Thought brushed polyimide is commercially widely used in LCD production there are many problems associated with mechanical rubbing; dust acting as nucleation seeds is one. By controlling nucleation, it becomes an advantage for bistable nematic liquid crystal displays. Fast responding, bistable twisted nematic displays (TN-LCDs) with high contrast and low driving voltage based on PI-alignment layers enabling controlled nucleation are reported. Controlled nucleation is powerful because of its simple structure and its compatibility with current LCD fabrication technologies. It has a high potential to be adapted to bistable, high resolution E-book or E-paper. Photoalignment is an advanced LC alignment technology that has been acknowledged as replacement for the conventional method of rubbed PI. Photoalignment requires no physical contact with the alignment film during processing. It avoids mechanical rubbing defect lines and static charging problems created by rubbing. The Azo-dye material azobenzene sulfuric sye SD1 developed at CDR is one of the promising photo-alignment materials, providing the highest azimuth anchoring energy. However, the re-writing behavior of SD1 which is inherent to Azo needs to be stabilized for most LCD applications. In this proposal, two we propose two methods for stabilizing SD1 alignment. The first is a stacking alignment method. The alignment film configuration consists of a stack of a thin photo-polymerisable liquid crystal pre-polymer film on top of an azo dye photo-alignment layer. The liquid crystal polymer acts as a passivation layer for the azo dye photoalignment layer. It prevents the alignment direction of the azo dye to be rewritten after the liquid crystal polymer is polymerized. The resulting liquid crystal polymer (LCP) alignment surface is robust and exhibits excellent stability. In addition, measurements show that the alignment properties of our stacked alignment surfaces are comparable to conventional polyimide alignment films. The proposed alignment layer is therefore suitable for in plane switching (IPS) liquid crystal displays which require high anchoring energy and very small residual direct current. Moreover, another new stabilization method for SD1 alignment films is proposed in this work. The key feature of the new aligning material is a mixing a liquid crystal pre-polymer with SD1. Films made with the novel alignment material exhibit as good alignment as those of pure azo-dye materials. Since no additional top layer is needed in this case and no additional synthesis effort is required, this method presents an easy way for fabricating stable LC-alignment films. Photo-stability against exposure to white and blue light is much improved compared with a pure SD1 layer.
Subjects/Keywords: Liquid crystal displays
; Liquid crystals
; Structure
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APA (6th Edition):
Tseng, M. C. E. (2016). Novel alignment surfaces for liquid crystal display. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-89664 ; https://doi.org/10.14711/thesis-b1584831 ; http://repository.ust.hk/ir/bitstream/1783.1-89664/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Tseng, Man Chun ECE. “Novel alignment surfaces for liquid crystal display.” 2016. Thesis, Hong Kong University of Science and Technology. Accessed March 02, 2021.
http://repository.ust.hk/ir/Record/1783.1-89664 ; https://doi.org/10.14711/thesis-b1584831 ; http://repository.ust.hk/ir/bitstream/1783.1-89664/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Tseng, Man Chun ECE. “Novel alignment surfaces for liquid crystal display.” 2016. Web. 02 Mar 2021.
Vancouver:
Tseng MCE. Novel alignment surfaces for liquid crystal display. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2016. [cited 2021 Mar 02].
Available from: http://repository.ust.hk/ir/Record/1783.1-89664 ; https://doi.org/10.14711/thesis-b1584831 ; http://repository.ust.hk/ir/bitstream/1783.1-89664/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Tseng MCE. Novel alignment surfaces for liquid crystal display. [Thesis]. Hong Kong University of Science and Technology; 2016. Available from: http://repository.ust.hk/ir/Record/1783.1-89664 ; https://doi.org/10.14711/thesis-b1584831 ; http://repository.ust.hk/ir/bitstream/1783.1-89664/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Colorado
29.
Schenkel, Magdalene Reynolds.
Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds.
Degree: PhD, Chemistry & Biochemistry, 2014, University of Colorado
URL: https://scholar.colorado.edu/chem_gradetds/117
► Thermotropic ionic liquid crystals (TILCs) are a relatively new field of liquid crystals (LCs) research. TILCs have the internal organization of traditionally uncharged LCs…
(more)
▼ Thermotropic ionic
liquid crystals (TILCs) are a relatively new field of
liquid crystals (LCs) research. TILCs have the internal organization of traditionally uncharged LCs as well as many of the unique characteristics of organic molten salts known as room-temperature ionic liquids (RTILs). Within the latter's family of `designer solvents', which include many ionic moieties with varying advantages, imidazolium salts offer a cheap and modular ionic moiety to build ionic organic compounds with characteristics tailored to specific needs. The advances in these ionic
liquid crystals (ILCs) have led to research in soft materials with improved gas separation, electrolytic, and reactive capabilities. However, the incorporated ionic units traditionally comprise very little of the overall architecture commonly found for ionic mesogens and are most often head or pendant groups, vestigial, or isolated from other ionic units present.
In this thesis research, calamitic, symmetrical, organic ionic compounds bearing a linearly linked tris(imidazolium) salt core were designed, synthesized and analysed for thermotropic LC behaviour. This unprecedented TILC design allowed for an increase in the number of imidazolium units per molecule compared to the vast majority of imidazolium-based TILCs reported in the literature. This new modular TILC platform also allowed the systematic study of three major factors in the molecular for potentially controlling LC behaviour: the hydrophobic tail length, the type of counter-ion, and the spacer length within the polyionic core. Each of these tris(imidazolium) compounds prepared were structurally characterized and then observed through variable-temperature polarized light microscopy (PLM) to determine their thermotropic mesogenic behaviour. Those compounds that exhibited thermotropic LC behaviour were then analysed with powder X-ray diffraction (PXRD) to confirm the structures of the presented LC phases. From these systematic studies, it was found that:
1) The length of the n-alkyl tails peripherally must be equal to or longer than the length of the ionic core into to properly separate between hydrophobic and ionophilic sections.
2) BF
4- anions permit shorter n-alkyl tails to produce TILC behaviour, and with wider mesogenic temperature ranges.
3) Only the longest tails in the series create TILCs when paired with Tf
2N
- anions, with higher order within the lamellar mesophase and with markedly smaller layers than with either BF
4- or Br
- counter-ions.
4) Extending the inner-core spacers from hexyl to octyl created only three TILCs, suggesting either the imidazolium moieties were too far apart to create an ionic section, or the overall length of the ionic organic compounds were too long to allow mesogenic behaviour.
5) Shortening the inner-core spacers also produced no mesogens regardless of n-alkyl tails and counter-ion species, suggesting the moieties within the ionic core were spaced…
Advisors/Committee Members: Douglas L. Gin, Richard D. Noble, Dave Walba, Matt A. Glaser, Wei Zhang.
Subjects/Keywords: imidazolium; ionic liquid crystals; liquid crystals; thermotropic; Organic Chemistry
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APA (6th Edition):
Schenkel, M. R. (2014). Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/117
Chicago Manual of Style (16th Edition):
Schenkel, Magdalene Reynolds. “Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds.” 2014. Doctoral Dissertation, University of Colorado. Accessed March 02, 2021.
https://scholar.colorado.edu/chem_gradetds/117.
MLA Handbook (7th Edition):
Schenkel, Magdalene Reynolds. “Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds.” 2014. Web. 02 Mar 2021.
Vancouver:
Schenkel MR. Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Mar 02].
Available from: https://scholar.colorado.edu/chem_gradetds/117.
Council of Science Editors:
Schenkel MR. Design, Synthesis, and Thermotropic Liquid Crystal Behavior of Novel Tris(imidazolium) Ionic Organic Compounds. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/chem_gradetds/117
University of Oxford
30.
Kischka, Claudius.
Flexoelectricity in nematic liquid crystals.
Degree: PhD, 2011, University of Oxford
URL: http://ora.ox.ac.uk/objects/uuid:224f9760-b082-467e-aa6e-56a5828fbcd5
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559774
► Flexoelectricity in liquid crystals is thought to be due to a coupling between dielectric properties and shape anisotropy of the molecules and described by the…
(more)
▼ Flexoelectricity in liquid crystals is thought to be due to a coupling between dielectric properties and shape anisotropy of the molecules and described by the flexoelectric coefficients e1 and e3. Two experiments are needed to measure e1 and e3 and it is usual to measure the difference (e1 − e3) and the sum (e1 + e3) and then calculate e1 and e3. The first experiment to measure the difference (e1 − e3) uses a TN structure with an in-plane applied electric field. Due to the dielectric coupling, the director aligns with the electric field and due to the flexoelectric effect, the director tilts out of plane. This tilt is measured optically using two laser beams at oblique incidence, e.g. 45◦ . Using a theoretical model the experimental data is fitted and the difference (e1 − e3) extracted. The second experiment to measure the sum (e1 + e3) uses a Pi cell. Applying an ac voltage the transmission through the device is a repeating oscillating signal which contains 1st and 2nd harmonics. The 1st harmonic corresponds to the flexoelectric effect and the 2nd harmonic to the dielectric effect. Using a lock-in amplifier, the harmonics were measured and the sum (e1 +e3) extracted using a theoretical model to fit the experimental data. Unfortunately, the data proved the experiment to be unreliable and another method was developed, which uses a HAN cell. The third experiment uses simple pulses in a HAN cell and also measures the sum (e1 + e3). The big disadvantage of the HAN cell is an internal voltage, which is created by the homeotropic alignment layer and the flexoelectric polarisation. The internal voltage has the same effect on the director profile as the flexoelectric effect, which is a big problem in measuring flexoelectricity. Using a material, which is non ionic and has no flexoelectricity, the internal bias could be measured and taken into account. Applying short dc pulses of opposite sign, the flexoelectric effect can be ii observed by the optical response and can be measured. Using these experiments, a number of investigation are being carried out such as the correlation between flexoelectricity and the molecular structure, ions, elastic properties, molecular orientation, dielectric anisotropy ∆ϵ, and order parameter S. The results showed that flexoelectricity only depends on ions and dielectric properties which was very interesting and surprising at the same time.
Subjects/Keywords: 530.429; Nematic liquid crystals; Liquid crystals – Electric properties
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APA ·
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Manager
APA (6th Edition):
Kischka, C. (2011). Flexoelectricity in nematic liquid crystals. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:224f9760-b082-467e-aa6e-56a5828fbcd5 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559774
Chicago Manual of Style (16th Edition):
Kischka, Claudius. “Flexoelectricity in nematic liquid crystals.” 2011. Doctoral Dissertation, University of Oxford. Accessed March 02, 2021.
http://ora.ox.ac.uk/objects/uuid:224f9760-b082-467e-aa6e-56a5828fbcd5 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559774.
MLA Handbook (7th Edition):
Kischka, Claudius. “Flexoelectricity in nematic liquid crystals.” 2011. Web. 02 Mar 2021.
Vancouver:
Kischka C. Flexoelectricity in nematic liquid crystals. [Internet] [Doctoral dissertation]. University of Oxford; 2011. [cited 2021 Mar 02].
Available from: http://ora.ox.ac.uk/objects/uuid:224f9760-b082-467e-aa6e-56a5828fbcd5 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559774.
Council of Science Editors:
Kischka C. Flexoelectricity in nematic liquid crystals. [Doctoral Dissertation]. University of Oxford; 2011. Available from: http://ora.ox.ac.uk/objects/uuid:224f9760-b082-467e-aa6e-56a5828fbcd5 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559774
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