Dissertations / Theses on the topic 'Liquid Crystalline Behavior'
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1
Tenneti, Kishore Kumar Li Christopher Yuren. "Nanoscale hierarchical phase behavior of liquid crystalline block copolymers /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2764.
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Moilanen, A. (Anu). "Self-association, compatibility, and strengthening behavior of liquid crystalline oligomers." Doctoral thesis, University of Oulu, 1998. http://urn.fi/urn:isbn:9514250915.
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Abstract
Synthetic routes were developed for the preparation of 2-alkoxy-4-hydroxybenzoic
acids and 2-alkoxyhydroquinones, and a large-scale synthesis was
developed for the preparation of 2-thioalkoxyhydroquinones. The
2-alkoxy-4-hydroxybenzoic acids, which contained alkyl side chains of
different length, were used in the synthesis of new main chain liquid
crystalline (LC) homo-, random, and block co-oligomers. In addition,
oligomers of terephthaloyl chloride and 2-thioalkoxyhydroquinones
and oligomers of terephthaloyl chloride and 2-alkoxyhydroquinones
were produced.
All the oligomers were blended with aliphatic polyamide 11
(PA 11). The effect of alkyl side chain length on the compatibility
behavior of the LC oligomers towards the aliphatic polymer was characterized
by DSC and FTIR, and the effect of side chain length on the flexural
properties of the blends was investigated with a three-point bending
test.
The miscibility studies showed variable interfacial adhesion
between the blended compounds. The strongest adhesion was achieved
between PA 11 and the homo-oligomers of 2-alkoxy-4-hydroxybenzoic
acids with short or medium long substituents (C4-C10),
but the interactions between PA 11 and the oligomer with long aliphatic
side chain (C18) were poor, as were those
between PA 11 and the wholly aromatic oligomer of 4-hydroxybenzoic
acid. The compatibility between PA 11 and the co-oligomers of 2-alkoxy-4-hydroxybenzoic
acids was slightly lower than the compatibility of the corresponding
homo-oligomers. DSC and FTIR analyses of the blends of oligomers
of terephthaloyl chloride and 2-thioalkoxyhydroquinones and oligomers
of terephthaloyl chloride and 2-alkoxyhydroquinones with PA 11 implied
that the interactions between the blended compounds were poor.
FTIR spectra and viscosity measurements confirmed that all
the oligomeric structures could self-associate, with effect on the
final mechanical properties of the polyamide. The strength of PA
11 in a three-point bending test was increased by the addition of
only 1% of LC oligomers to the matrix. The results also
showed that the strengthening ability of the oligomers is directly
proportional to the total amount of aliphatic carbons. The best
strengthening results were obtained with unsubstituted oligomers,
random co-oligomers of 2-alkoxy-4-hydroxybenzoic acids, and homo-oligomer
of 2-butoxy-4-hydroxybenzoic acid.
DSC investigations of a ternary blend of the oligomer of 2-decanyloxy-4-hydroxybenzoic
acid, PA 11, and wholly aromatic commercial LC polymer showed the
promising compatibilizing effect of the oligomer.
3
JEONG, SEUNG YEON. "Liquid crystalline behavior of mesogens formed by anomalous hydrogen bonding." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1304649634.
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Thorson, Todd James. "Phase behavior and stimuli response in lyotropic liquid crystalline templated photopolymers." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2646.
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Simoes, Ricardo J. F. "Mechanical behavior and performance of injection molded semi-crystalline polymers." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc5528/.
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I have used computer simulations to investigate the behavior of polymeric materials at the molecular level. The simulations were performed using the molecular dynamics method with Lennard-Jones potentials defining the interactions between particles in the system.
Significant effort was put into the creation of realistic materials on the computer. For this purpose, an algorithm was developed based on the step-wise polymerization process. The resulting computer-generated materials (CGMs) exhibit several features of real materials, such as molecular weight distribution and presence of chain entanglements.
The effect of the addition of a liquid crystalline (LC) phase to the flexible matrix was also studied. The concentration and distribution of the second phase (2P) were found to influence the mechanical and tribological properties of the CGMs. The size of the 2P agglomerates was found to have negligible influence on the properties within the studied range. Moreover, although the 2P reinforcement increases the modulus, it favors crack formation and propagation. Regions of high LC concentration exhibit high probability of becoming part of the crack propagation path. Simulations of the tensile deformation under a uniaxial force have shown that the molecular deformation mechanisms developing in the material depend on several variables, such as the magnitude of the force, the force increase rate, and the level of orientation of the chains. Three-dimensional (3D) graphical visualization tools were developed for representation and analysis of the simulation results. These also present interesting educational possibilities. Computer simulations provide us information which is inaccessible experimentally. From the concomitant use of simulations and experiments, a better understanding of the molecular phenomena that take place during deformation of polymers has been established.
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Verploegen, Eric Anton. "Morphology and self-assembly behavior of side chain liquid crystalline block copolymers." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44386.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references.
There is significant interest from both the academic and industrial communities for understanding and controlling the self-assembly behavior of complex macromolecular systems and has been an active area of research in recent years. Such systems can be designed to result in a wide range of nanoscale morphologies and greater functionality can be introduced with increasing complexity.This thesis focuses on the synthesis and characterization of a class of side chain liquid crystalline block copolymers (SCLCBCPs) that are based on a low glass transition temperature (Tg) siloxane backbone. Moieties that self-assemble into smectic liquid crystalline (LC) phases are covalently attached to the polystyrene-polyvinylmethylsiloxane (PS-PVMS) block copolymer backbone. Precise control over the functionalization of the LCs onto the functional siloxane backbone allows for unique control over the self-assembly and the resulting properties of the system. The LC content significantly affects the stability of the smectic mesophase and subsequently the interactions with the inter-material dividing surface (IMDS) with the PS domains. A strong preference for homogenous anchoring of the LC moieties relative to the IMDS is observed, and increasing the LC content intensifies the preference for this arrangement. Utilizing the effects of LC anchoring to alter the self-assembly behavior is a reoccurring theme throughout this work. Additionally, the mechanical properties of these materials can be precisely manipulated over several orders of magnitude through variations in LC content and the block copolymer backbone architecture.Several methods can be used to manipulate the morphologies of these materials once synthesized including, thermal annealing and mechanical deformation.
(cont.) Thermal annealing provides additional mobility for self-assembly often resulting in morphological rearrangements. Mechanical deformation can be used to orient the self-assembled structures relative to an applied shear flow. Additionally, the self-assembled morphologies of spin cast into thin films were investigated. The presence of the substrate has significant effects upon the orientation of the morphologies; thermal annealing and variations liquid crystal content are shown to be useful tools for achieving a wide range of thin film morphologies.
by Eric Anton Verploegen.
Ph.D.
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Zhou, Weijun Kornfield Julia A. Kornfield Julia A. "Dynamics and shear alignment behavior of a model thermotropic liquid crystalline polymer /." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-08292008-110129.
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Khennache, Omar. "Factors influencing product microstructure and the injection molding behavior of liquid crystalline polymers." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74663.
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Liquid Crystal Polymers (LCP) are a new class of polymeric materials with special molecular and solid state structures, flow characteristics and mechanical properties. Injection molded articles of rigid chain liquid crystal copolymers (LCP's) are gaining increasing commercial importance because their dimensional stability, high stiffness and strength per unit weight, make them highly attractive for aerospace structures and automotive parts, where the anisotropic nature of the materials can be exploited to achieve novel design strategies. Considerable technological importance is given to thermotropic LCP's because of their melt phase behavior and ease of processing. Because of their comparatively low viscosity, they can be injection molded with short cycle times into thin and complex shapes.In the present work, broad range of material properties, including specific heat, thermal conductivity, thermal diffusivity, and shear viscosity of a commercial LCP injection molding resin have been determined experimentally. In addition, a detailed experimental study has been made of the crystallization kinetics of this LCP resin. The study showed that the resin undergoes two crystallization mechanisms, a fast and a slow mechanism, depending on the temperature and the cooling rates.
Various experimental techniques, to characterize the microstructure of the molded parts, including morphology, orientation, crystallinity and mechanical properties, have been developed and used. An effort is made to explain the results. Furthermore, composite theory is employed to explain the mechanical properties in light of microstructural observations. Overall, the present work represents the most comprehensive effort to date to study and explain the processing-microstructure-property relationships for injection molded LCP's.
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Ren, Wanting. "Structure-property Relations of Siloxane-based Main Chain Liquid Crystalline Elastomers and Related Linear Polymers." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16248.
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Soft materials have attracted much scientific and technical interest in recent years. In this thesis, attention has been placed on the underpinning relations between molecular structure and properties of one type of soft matter - main chain liquid crystalline elastomers (MCLCEs), which may have application as shape memory or as auxetic materials. In this work, a number of siloxane-based MCLCEs and their linear polymer analogues (MCLCPs) with chemical variations were synthesized and examined. Among these chemical variations, rigid p-phenylene transverse rod and flat-shaped anthraquinone (AQ) mesogenic monomers were specifically incorporated. Thermal and X-ray analysis found a smectic C phase in most of our MCLCEs, which was induced by the strong self-segregation of siloxane spacers, hydrocarbon spacers and mesogenic rods. The smectic C mesophase of the parent LCE was not grossly affected by terphenyl transverse rods. Mechanical studies of MCLCEs indicated the typical three-region stress-strain curve and a polydomain-to-monodomain transition. Strain recovery experiments of MCLCEs showed a significant dependence of strain retentions on the initial strains but not on the chemical variations, such as the crosslinker content and the lateral substituents on mesogenic rods. The MCLCE with p-phenylene transverse rod showed a highly ordered smectic A mesophase at room temperature with high stiffness. Mechanical properties of MCLCEs with AQ monomers exhibit a strong dependence on the specific combination of hydrocarbon spacer and siloxane spacer, which also strongly affect the formation of ð-ð stacking between AQ units. Poisson s ratio measurement over a wide strain range found distinct trends of Poisson s ratio as a function of the crosslinker content as well as terphenyl transverse rod loadings in its parent MCLCEs.
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Koch, Karin [Verfasser]. "Ferronematic phases with strong coupling behavior based on liquid crystalline polymer decorated nanoparticles / Karin Koch." München : Verlag Dr. Hut, 2021. http://d-nb.info/1240540086/34.
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Qian, Chen. "Linking the Rheological Behavior to the Processing of Thermotropic Liquid Crystalline Polymers in the Super-cooled State." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/75005.
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Thermotropic liquid crystalline polymers (TLCPs) have attracted great interest because of the combination of their promising properties, which includes high stiffness and strength, excellent processability, and outstanding chemical resistance. TLCPs exhibit inherently low viscosity relative to many other conventional thermoplastics. The low melt viscosity is detrimental to processes requiring high melt strength, such as extrusion blow molding, film blowing, thermoforming and multilayer coextrusion. Our laboratory has developed a unique method to increase the viscosity of TLCPs by first raising the temperature above the melting point (Tm) to exclude all solid crystalline structure, and then lowering the temperature below Tm to super cool the materials. Additionally, the super-cooling behavior of TLCPs allows them to be blended with other thermoplastics possessing lower processing temperatures.
The initial focus of this dissertation is to investigate the processing temperature of a representative TLCP in the super-cooled state, using the methods of small amplitude oscillatory shear (SAOS), the startup of shear flow and differential scanning calorimetry (DSC). The TLCP used in this work is synthesized from 4-hydroxybenzoic acid (HBA), terephthalic acid (TA), hydroquinone (HQ) and hydroquinone derivatives (HQ-derivatives). The TLCP of HBA/TA/HQ/HQ-derivatives has a melting point, Tm, of around 280 oC. Once melted, the TLCP can be cooled 30 oC below the Tm while still maintaining its processability. As the TLCP was cooled to 250 oC, a one order magnitude increase in viscosity was obtained at a shear rate of 0.1 s-
1. Additionally, super cooling the TLCP did not significantly affect the relaxation of shear stress after preshearing. However, the recovery of the transient shear stress in the interrupted shear measurements was suppressed to a great extent in the super-cooled state.
The second part of this work is concerned with the extrusion blow molding of polymeric blends containing the TLCP of HBA/TA/HQ/HQ-derivatives and high density polyethylene (HDPE), using a single screw extruder. The blends were processed at a temperature of 260 oC which is 20 oC below Tm of the TLCP such that the thermal degradation of HDPE was minimized. Bottles were successfully produced from the blends containing 10, 20 and 50 wt% TLCP. The TLCP/HDPE blend bottles exhibited an enhanced modulus relative to pure HDPE. However, the improvement in tensile strength was marginal. At 10 and 20 wt% TLCP contents, the TLCP phase existed as platelets, which aligned along the machine direction. A co-continuous morphology was observed for the blend containing 50 wt% TLCP. The preliminary effectiveness of maleic anhydride grafted HDPE (MA-g-HDPE) as a compatibilizer for the TLCP/HDPE system was also studied. The injection molded ternary TLCP/HDPE/MA-g-HDPE blends demonstrated superior mechanical properties over the binary TLCP/HDPE blends, especially in tensile strength. Consequently, it is promising to apply the ternary blends of TLCP/HDPE/MA-g-HDPE in the blow molding process for improved mechanical properties.
Finally, this work tends to determine how the isothermal crystallization behavior of a TLCP can be adjusted by blending it with another TLCP of lower melting point. One TLCP (Tm~350 oC) used is a copolyester of HBA/TA/HQ/HQ-derivatives with high HBA content. The other TLCP (Tm~280 oC) is a copolyesteramide of 60 mol% hydroxynaphthoic acid, 20 mol% terephthalic acid and 20 mol% 4-aminophenol. The TLCP/TLCP blends and neat TLCPs were first melted well above their melting points, then cooled to the predetermined temperatures below the melting temperatures at 10 oC/min to monitor the isothermal crystallization. As the content of the low melting TLCP increased in the blends, the temperature at which isothermal crystallization occurred decreased. Comparing with neat TLCPs, the blend of 75% low melting TLCP crystallized at a lower temperature than the pure matrices, and the blend remained as a stable super-cooled fluid in the temperature range from 220 to 280 oC. Under isothermal conditions, differential scanning calorimetry (DSC) was not capable of reliably detecting the the low energy released in the initial stage of crystallization. In contrast, small amplitude oscillatory shear (SAOS) was more sensitive to detecting isothermal crystallization than DSC.Ph. D.
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Murphy, Lindsay Adams. "Morphological investigation of AFR-PEPA-N imide oligomers and their cured polyimides and the remodification of AFR-PEPA-N to achieve liquid-crystalline behavior." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1174.
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The morphological investigation of AFR-PEPA-N and the development of a new polyimide have been established herein. AFR-PEPA-N is an imide oligomer that was created out of the need to attain a high temperature polyimide that is also resistant to hygrothermal and thermooxidative degradation. Previously, AFR700B was implemented in aerospace applications, but it was found to be hygrothermally unstable. It experienced a severe drop in its glass transition temperature and composite blistering. AFR700B was improved upon, by altering the chemical structure of the polyimide. The nadic end-cap was removed and replaced by a more hydrolytically stable end-cap. However this phenylethynyl-terminated end-group could possibly create semi-crystallinity or liquid-crystalline characteristics within the polymer.
Previous research suggests further study of the relationships between AFR-PEPA-N's oligomer crystallinity and the properties of phenylethynyl-terminated polyimides. This understanding is valuable in processing AFR-PEPA-N by resin transfer molding (RTM) to obtain its optimum properties. The investigation included the identification of a processing window, temperature overlap between the melting of residual crystals and crosslinking reactions, and liquid crystallinity behavior. These reactions were investigated primarily through birefringence.
The residual crystals were found to be innate in the oligomer powder and not created by preliminary thermal processing. Therefore a reasonable processing window was found based upon the reduction of crystal size by appropriate dissolution techniques. Possible nematic liquid-crystalline characteristics were found to be present at 360oC.
A new imide oligomer, which was based upon AFR-PEPA-N's original structure, was synthesized. The non-linear, flourinated backbone of AFR-PEPA-N was replaced with a co-linear backbone, pyromellitic dianhydride (PMDA). These modifications were made in hopes to improve upon the network structure by it becoming more regular and resistance to nano-sized defects in the final crosslinked structure. The initial characterization found that the new polyimide, AFR-P3, displayed a cure temperature at 350oC. The degree of cure reaches about 80 to 90 percent complete based upon the consumption of the carbon-triple bond. AFR-P3 did not show signs of liquid-crystalline behavior. However, there will be future work in creating a more rigid-rod, self-assembling oligomer that can attain optimum thermal and mechanical properties.
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Kress, Oliver Herbert [Verfasser], Tanya [Akademischer Betreuer] Ostapenko, Jörg [Gutachter] Enderlein, and Simone [Gutachter] Techert. "The Viscoelastic Response of Liquid Crystalline Fibers Formed By Bent-core Molecules : From Microscopic Ordering to Macroscopic Behavior / Oliver Herbert Kress ; Gutachter: Jörg Enderlein, Simone Techert ; Betreuer: Tanya Ostapenko." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1200209176/34.
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Wongkhan, Kittiya. "Synthesis and applications of palladium complexes : Part I. The synthesis, single crystal structures and liquid crystalline phase behavior of alkoxy substituted Tolans; Part II. Palladium-complexes of thioureas and phosphine sulfides." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2139/.
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Three series of alkoxy substituted tolans p-X-C(_6)H(_4)-C≡C-C(_6)H(_4)-p-OC(_n)H(_2n+1) [X = H (series 1), CH(_3) (series 2), OCH(_3) (series 3)] with varying chain length were synthesized by Pd/Cu-catalysed Sonogashira cross-coupling reactions of terminal alkynes and iodoarenes, crystal structures and phase behavior of three series of tolans. Twenty-eight of the tolans were structurally characterised by single-crystal X-ray diffraction. Their phase behavior was characterised by tplm; only the tolans in series 3 show liquid crystalline phases. The melting points of the tolans decrease with increasing chain length due to a higher degree of flexibility of the terminal chain. An odd-even effect is clearly observed for the clearing point of the nematic phase upon both heating and cooling, with the higher temperature for even and low temperature for odd number carbon chains for series 3.Monomeric and dimeric palladium dichloride complexes containing the monodentate thioureas, tetramethyl thiourea (tmtu) and a chiral C(_2) symmetric thiourea were synthesized. Their structures were obtained from single-crystal X-ray diffraction. The structures of the mono-palladium complexes are the trans-isomers, whereas the dimer complexes present cis-configurations, and are also the first examples of palladium complexes with sulfur-bridging thiourea ligands. NMR studies of the monomeric and dimeric complexes with tmtu reveal that, in solution, the dimeric complexes are interconverting with mono-palladium complexes, which suggests that the systems are labile. A dynamic equilibrium in solution was also observed between the rac- and meso-dipalladium complexes with the C(_2)-symmetric ligand. The energy barrier to exchange was obtained from a variable temperature NMR study. It is proposed that this equilibrium results from the monomer-dimer interconversion. S,N-bidentate ß-dimethyl and ß-monomethyl oxazoline thiourea ligands and α-isoquinoline thiourea ligands and their palladium complexes have been obtained. Single-crystal X-ray diffraction analyses allow us to distinguish between some of their atropoisomers and diastereomers. Most of the Pd complexes were shown to be monomers in the solid state, although one ligand with a cyclohexyl group formed exclusively dimers, and one formed a trimer, as well as a monomer, depending on the solvent mixture that the crystals were grown from. The ligands were found to coordinate through their S and N atoms. All of the mono-palladium complexes and most of the dimers have cis-configurations at the Pd centers; however, we also found a trans-configuration in the trimer and the dimer of one of the palladium complex of the ß-monomethyl ligands. The structures show that the ß- monomethyl oxazoline and a-isoquinoline thiourea complexes appear to be more weakly coordinated than the ß-dimethyl oxazoline ones which may be responsible for their lower stabilities in solution. The structure of the ligands (in particular the 'up' or 'down' conformation of the atropoisomers) is intimately related to their enatioselectivities in bis(methoxycarbonylation) reactions of styrene using palladium complexes. The ß-dimethyl ligands were, in general, found to be more selective in this reaction than the ß -monomethyl oxazoline ones, with palladium complexes of the latter generally found to be less stable in NMR studies. Several bis(phosphine) monosulfide and disulfide ligands and their palladium complexes have been synthesized and analyzed by single-crystal X-ray diffraction. The reaction with 1:1 molar ratios of Pd source to monosulfide ligands were found to produce monomeric palladium complexes with chelating ligands, apart from the reaction with is(diphenylphosphino)butane monosulfide, which was found to result in a dimer being formed. The reactions with 1:2 molar ratios of Pd source to monosulfide ligand gave complexes which were coordinated only through the phosphine groups, except for that with bis(diphenylphosphino)methane monosulfides which formed cafionic palladium complexes with two chelating ligands. Analogous reactions with the disulfide ligands and the Pd source [Pd(CH(_3)CN)(_4)](BF(_4))(_2) also resulted in cationic Pd complexes incorporating two chelating ligands. In some cases, in solution, the complexes showed dynamic equilibria between cis- and trans- isomers which suggests that the phosphine sulfide ligands are labile. The Pd-S-P angles in the complexes were found to be variable but, since there are none less than 90, it is unlikely that there is any ƞ(^2)-π bonding involving the P=S bond. Preliminary results show that the activities of phosphine sulfide palladium complexes in the oxidative homo-coupling of phenylacetylene are comparable to that of the commonly used pre-catalyst, PdCl(_2)(PPh(_3))(_2).
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Mateer, Donna Louise. "The liquid-crystalline behaviour of photographic sensitising dyes." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360349.
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Madden, Andrea. "Phase behaviour of side-chain liquid-crystalline polymers." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241165.
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Lavine, Marc Stuart. "Modelling of defect behaviour in nematic liquid crystalline materials." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627290.
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Duesing, Peter Michael. "Effects of pressure on lyotropic liquid-crystalline phase behaviour and structure." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294919.
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Flood, Joseph. "Solution and liquid crystalline properties of sodium lauroyl methyl isethionate/water mixtures." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/solution-and-liquid-crystalline-properties-of-sodium-lauroyl-methyl-isethionatewater-mixtures(d9f043f2-3ca6-4a13-b3f0-d5d5eae83bfc).html.
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The project contributes to the general theme of complex chemical systems and strengthens ties with Innospec, a multi-national chemical company. Sodium lauroyl methyl isethionate (SLMI. Trade name “Iselux”) is a newly developed surfactant with attractive product properties for personal care applications. Little is known about the fundamental surface and solution properties of SLMI, and it is not currently possible to use information on available surfactants to predict phase behaviour. We characterise the solution and liquid crystalline phase behaviour of the SLMI/water system using a combination of optical microscopy, X-ray scattering and differential scanning calorimetry techniques. SLMI is synthesised using a batch process that leads to variable component concentrations. Preliminary studies conducted by Innospec indicate that the presence of particular process components has a significant influence on SLMI formulation rheological properties. We investigate the effects of synthesis-derived components on the rheological properties of the SLMI/sodium {(3-(dodecanoylamino)propyl)(dimethyl)ammonio)}acetate/water system using rheology and light scattering (static and dynamic) techniques. SLMI is often formulated into personal care products on mixing aqueous formulation components. Micelle growth occurs via a mechanistic process that is not understood and the equilibrium viscosity is attained at a time after mixing that ranges from seconds to weeks. Developing an improved understanding of the micelle growth mechanism is of both academic and industrial value. We utilise static light scattering and nuclear magnetic resonance techniques to probe a range of samples in the viscoelastic region of the SLMI/(carboxymethyl)hexadecyldimethyl ammonium hydroxide/water system. Experimental findings improve our current understanding of micelle growth process and provide a platform for future research on non-equilibrium mixing kinetics. In the final section we investigate salt-induced cloud point and precipitation phenomena in the SLMI/salt/water system. The cloud point is commonly observed in surfactant and protein systems by increasing the solution temperature above a critical value, resulting in phase separation of solute-rich and solute-depleted layers. Cloud point induced phase separation may also be prompted by addition of salt. The mechanistic process driving electrolyte-induced cloud point phenomena is not understood. We use a combination of turbidimetry measurements and lightscattering (static and dynamic) techniques to measure cloud point curves andcharacterise micellar behaviour prior to clouding.
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Stimson, Lorna M. "Phase behaviour of macromolecular liquid crystalline materials : computational studies at the molecular level." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/3144/.
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Molecular simulations provide an increasingly useful insight into the static and dynamic characteristics of materials. In this thesis molecular simulations of macro-molecular liquid crystalline materials are reported. The first liquid crystalline material that has been investigated is a side chain liquid crystal polymer (SCLCP). In this study semi-atomistic molecular dynamics simulations have been conducted at a range of temperatures and an aligning potential has been applied to mimic the effect of a magnetic field. In cooling the SCLCP from an isotropic melt, microphase separation was observed yielding a domain structure. The application of a magnetic field to this structure aligns the domains producing a stable smectic mesophase. This is the first study in which mesophases have been observed using an off-lattice model of a SCLCP. The second material that has been investigated is a dendrimer with terminal mesogenic functionalization. Here, a multi-scale approach has been taken with Monte Carlo studies of a single dendrimer molecule in the gas phase at the atomistic level, semi-atomistic molecular dynamics of a single molecule in liquid crystalline solvents and a coarse-grained molecular dynamics study of the dendrimer in the bulk. The coarse-grained model has been developed and parameterized using the results of the atomistic and semi-atomistic work. The single molecule studies showed that the liquid crystalline dendrimer was able to change its structure by conformational changes in the flexible chains that link the mesogenic groups to the core. Structural change was seen under the application of a mean field ordering potential in the gas phase, and in the presence of liquid crystalline solvents. No liquid crystalline phases were observed for the bulk phase studies of the coarse-grained model. However, when the length of the mesogenic units was increased there was some evidence for microphase separation in these systems.
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Uhl, Benedikt [Verfasser]. "Adsorption behavior and structure formation of ionic liquids on single crystalline surfaces / Benedikt Uhl." Ulm : Universität Ulm, 2017. http://d-nb.info/112552815X/34.
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Gana, Inès. "Caractérisation physique et chimique des substances à activité thérapeutique : application aux études de profil de stabilité et de préformulation." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB164/document.
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Le développement d’un médicament pour une cible thérapeutique donnée passe par plusieurs étapes qui se résument en une étape de criblage, une phase préclinique et plusieurs phases cliniques. Ces étapes permettent de sélectionner une substance active et de démontrer son efficacité thérapeutique et sa sécurité toxicologique. Ces deux critères définissent la qualité du médicament qui, une fois démontrée, doit être garantie pendant toute sa durée de validité. La qualité est évaluée au moyen d’études de stabilité qui sont réalisées d’abord sur la matière première de la substance active au cours de la phase de pré-développement du médicament, ensuite sur le produit fini. La stabilité intrinsèque de la substance active concerne à la fois ses propriétés chimiques et ses propriétés physiques qui sont liées à la nature de la substance. L’étude de stabilité repose d’abord sur la caractérisation de ces propriétés, et ensuite sur l’étude de la sensibilité de la substance à l’égard des facteurs environnementaux pouvant modifier les propriétés intrinsèques de la substance. L’approche adoptée dans ce travail repose d’une part sur l’évaluation de la stabilité chimique c’est à dire de la réactivité chimique des substances à usage pharmaceutique au travers des études de pureté chimique et des études de dégradation forcée de ces substances en solution, et d’autre part, sur l’évaluation de la stabilité physique. Dans ce cadre, l’étude du polymorphisme cristallin revêt une grande importance, tout comme l’aptitude à la formation d’hydrates ou de solvates. Cette étude, basée sur la thermodynamique, consiste pour l’essentiel à construire un diagramme de phases pression-température permettant de définir les domaines de stabilité relative des différentes formes cristallines. Cinq substances actives, existant à l’état solide et entrant dans la composition de médicaments administrés par voie orale, ont été étudiées dans le cadre de ce travail. L’analyse chimique du tienoxolol, présentant un effet anti-hypertenseur, a montré qu’il est très sensible à l’hydrolyse et à l’oxydation. Sept produits de dégradation ont été identifiés pour ce produit dont un schéma probable de fragmentation a été établi. Des diagrammes de phases pression-température ont été construits pour le bicalutamide et le finastéride, médicaments du cancer de prostate, en utilisant une approche topologique basée simplement sur les données disponibles dans la littérature. Cette étude a montré que la relation thermodynamique (énantiotropie ou monotropie) entre les formes cristallines sous conditions ordinaires peut être modifiée en fonction de la température et de la pression. Ce résultat est important pour la production des médicaments car il montre comment une telle information peut être obtenue par des mesures simples et accessibles aux laboratoires de recherche industrielle, sans que ces derniers soient contraints d’expérimenter sous pression. La méthode topologique de construction de diagramme de phases a été validée ensuite en la comparant à une méthode expérimentale consistant à suivre, par analyse thermique, des transitions de phases en fonction de la pression. La méthode expérimentale a été appliquée à deux composés, la benzocaine, anesthésique local, et le chlorhydrate de cystéamine, médicament utilisé pour les cystinoses. Les deux formes étudiées de benzocaine présentent une relation énantiotrope qui se transforme en relation monotrope à haute pression. Une nouvelle forme cristalline (forme III) du chlorhydrate de cystéamine a été découverte au cours de ce travail. La relation thermodynamique entre cette forme III et la forme I est énantiotrope dans tout le domaine de température et de pression. De plus, le chlorhydrate de cystéamine, classé hygroscopique, a fait l’objet d’une étude quantitative de sa sensibilité à l’eau, montrant qu’il devient déliquescent sans formation préalable d’hydrate (...)The development of a drug for a given therapeutic target requires several steps, which can be summarized by drug screening, a preclinical phase and a number of clinical phases. These steps allow the selection of an active substance and a verification of its therapeutic efficacy and toxicological safety. The latter two criteria define the quality of the drug, which once demonstrated, must be guaranteed throughout its shelf life. Quality is assessed through stability studies that are carried out with the raw material of the active substance (preformulation phase) and with the final product. The intrinsic stability of the active substance depends on its chemical and physical properties and their characterization is the core of the stability studies, which in addition consists of sensitivity studies of the active pharmaceutical ingredient (API) for environmental factors that can modify the intrinsic properties of the substance. The approach presented in this work is based on the one hand on the assessment of the chemical stability, i.e. the reactivity of APIs through chemical purity studies and forced degradation in solution, and on the other hand on the assessment of the physical stability. For the latter, crystalline polymorphism is of great importance, as is the ability of the API to form hydrates or solvates. The study of crystalline polymorphism is based on the construction of pressure-temperature phase diagrams in accordance with thermodynamic requirements leading to the stability condition domains of the different crystalline forms. The stability behavior of five APIs used or meant for oral applications has been studied as part of this work. The chemical analysis of tienoxolol, an antihypertensive drug, has demonstrated its sensitivity for hydrolysis and oxidation. Seven degradation products were identified and patterns of fragmentation have been established. Pressure-temperature phase diagrams have been constructed for bicalutamide and finasteride, drugs against prostate cancer, using a topological approach based on data available in the literature. The study demonstrates that the thermodynamic relationship (enantiotropy or monotropy) between crystalline forms under ordinary conditions can change depending on the pressure. This is important for drug development as it demonstrates how stability information can be obtained by standard laboratory measurements accessible to industrial research laboratories without the necessity to carry out experiments under pressure. The topological approach for the construction of phase diagrams has subsequently been validated by measuring transition temperatures as a function of pressure. Experiments have been carried out with benzocaine, a local anesthetic, and with cysteamine hydrochloride, a drug used against cystinosis. Two crystalline forms were observed in the case of benzocaine. They exhibit an enantiotropic relationship that becomes monotropic at high pressure. For cysteamine hydrochloride, a new crystalline form (form III) was discovered. The thermodynamic relationship between the new form III and the known form I is enantiotropic for the entire temperature and pressure range. Cysteamine hydrochloride’s sensitivity to water has been studied, as it is hygroscopic. It has been demonstrated that it becomes deliquescent in the presence of water and no trace of a hydrate has been found. Finally, a study combining thermal and chromatographic methods showed that, under the effect of temperature, cysteamine hydrochloride turns into cystamine in the solid as well as in the liquid state, The latter is known to be an important impurity of cysteamine hydrochloride. In conclusion, the approach developed in this work allowed to characterize the stability properties of a number of APIs and to determine the factors that may change these properties and influence the intrinsic stability (...)
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Wu, Tzu-Yen, and 吳姿燕. "Electrorheological Behavior of Nematic Liquid Crystal and Liquid Crystalline Copolymer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/7pa3s6.
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碩士國立臺北科技大學
有機高分子研究所
97
This study consist of two parts. The first part focuses on the electrorheological effect of homogeneous electrorheological fluid in regard to liquid crystalline copolymer, PBLG-PDLG Poly(γ-benzyl L-glutamate-co-γ-dodecyl L-glutamate),the molecule packing of α-helical poly(γ-benzyl L-glutamate) with n-alkyl side chain of various lengths (number of carbons in the alkyl group m = 12), were studied by means of 1H-NMR and polarized optical microscope. The liquidcrystalline copolymer with the permanent dipole along the helix axis is expected to show electrorheological effect under DC field. This study employed a parallel plate rheometer, Physica MCR 301, to investigate the viscosities of liquid crystalline copolymer under the changes in electric field strength. An apparent increase in viscosity was found when the electric field was applied. It was attributed to the formation of molecule structures along the electric field resulted from the interaction between the liquid crystalline molecules. The flow resistance was consequently enhanced. The second part is investigated the rheological properties of liquid crystal compound, 7OCB ( 4-cyano-4’-n-heptyloxybiphenyl ), subjected into an electric field. The viscoelastic properties of the liquid crystals were measured by the parallel plate viscometer, Physica MCR 301. Similar to the previous study, the electrorheological behavior was depended on the electric field strengths and temperatures. Within the temperature range of a nematic phase, the shear stress increase with amplitude of the electric field, and has different change with the temperature.
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Fynewever, Herb. "Phase behavior and local structure of liquid crystalline polymers." 1998. http://catalog.hathitrust.org/api/volumes/oclc/42697798.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1998.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 115-124).
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Chiu, Chien-Yu, and 邱建育. "Study of the Transient Electrorheological Behavior of Liquid Crystalline Polymer." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/36457437598953132868.
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碩士東海大學
化學工程學系
85
PHIC為帶有偶極矩之棒型高分子，具有成為單相型電流變流體的潛 力。本研究係使用RDAII 流變儀對主鏈型液晶高分子PHIC的溶液進行流變 鬆弛測試。所進行的測試方式是將試樣在定電場下進行固定剪切率的運動 至達到穩態後將電場去除然後觀察其力矩鬆弛與時間的關係。由實驗結果 發現此鬆弛行為是剪切率、電場強度與溶液的形態的函數。所有的鬆弛行 為有兩種基本模式：其一為單調遞減模式，另一種模式則有先出現下凹再 緩增逼近穩態值。在所探討的剪切率範圍內，低濃度的等向性溶液僅顯現 第一種模式；兩相性溶液則在低剪切率時遵循第一種模式，在較高的剪切 率則轉成第二種模式。在兩種模式中，高剪切率與高電場強度都會導致鬆 弛過程的初期應力有較迅速的降低。在力矩標準化之後，定剪切率下不同 電壓的單調遞減模式都可以整合成一條統一的主線。而下凹緩增模式則於 特定高剪切率範圍內亦可以用一條主線加以統合。 We studied the relaxation behavior of solutions of a liquid crystalline polymers, Poly(n-hexyl isocyanate), or PHIC which has the potential to be a novel single phase electrorheological(ER) fluid. The relaxation from an imposed electric field of a steady shear was found to be a function of shear rate, electric field strength and morphology of the solutions. Two patterns of the relaxation were observed. One of them was simply a monotonic decay and the other exhibited a under shoot followed by a gradualapproach to the new steady value. Over the shear rates investigated, the isotropic solutions always followed a monotonic pattern while the biphasic solutions exhibited both patterns depending on the shear rates. In both patterns, higher shear rates and higher field strengths induced a more rapid reduction of the stress in the beginning of the relaxation process. It was found that for both morphologies, the monotonic decaying curves can be superposed into a master curve by normalization, while for the pattern of under shoot, the master curve exits only for some range of high shear rates.
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WANG, YING-HONG, and 王穎鴻. "Liquid crystalline schiff base with cyanate terminalse synthesis and cure behavior." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/39571104719746905205.
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Chou, Jui-wen, and 周瑞雯. "A study of crystallization behavior and liquid-liquid phase separation of immiscible binary crystalline polymer blends." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/67235063942393408372.
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碩士國立臺灣科技大學
工程技術研究所材料科技學程
89
We use polarized optical microscopy(POM), differential scanning calorimeter (DSC) and stactic birefringence to probe the liquid-liquid phase separation as well as the crystallization and the melting behavior of a binary crystalline polymer blends of syndiotactic polypropylene(sPP) and random poly(propylene-co-ethylene)(PEP). We find that both liquid-liquid phase separation rate and crystallization rate are greatly influenced by the initial melting temperature and final crystallization temperature. The resulting structures of blends samples vary with the initial temperature, the crystallization temperature, as well as the polymer component. Due to the competition between liquid-liquid phase separation and crystallization of both components, the blend samples are immiscible even when the temperatures above the melting points. While from the static birefringence experiment, we can not get the transition temperature from two separated liquid-liquid phases to one disordered phase. This is due to the fact that though both components are immiscible, the separated domains are still randomly distributed such that birefringence intensity is zero. When a few amount of component B is added to component A, the crystal growth rate as well as the crystallinity of A decrease; however the nucleation rate increases, such that the total crystallization rate reaches a maximum when the blending ratio of sPP and PEP are in the range of 3/7 and 1/9.
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Zhou, Weijun. "Dynamics and shear alignment behavior of a model thermotropic liquid crystalline polymer." Thesis, 2001. https://thesis.library.caltech.edu/3274/1/Zhou_w_2001.pdf.
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NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
Although liquid crystalline polymers (LCPs) emerged as important engineering materials in the early 1970s, the current level of understanding still falls short of allowing deliberate manipulation of macroscopic orientation, leading to poor control of morphology and material properties. The flow behavior of rod-like LCP solutions (lyotropic) are fairly well understood, yet little progress has been made on LCP melts (thermotropic) because of the formidable experimental difficulties with commercial thermotropes. A simple extension of the knowledge obtained from rod-like LCP solutions to thermotropic LCPs is unlikely to hold due to the enhanced molecular flexibility and intimate molecular contact in LCP melts.
The primary concern of this thesis is therefore the flow behavior of thermotropic LCPs, with an emphasis on how flow influences orientation and morphology and how this depends on molecular structure. For this purpose we synthesized a model thermotropic LCP selected for its chemical stability, wide nematic range and optical transparency. This main-chain LCP, designated as DHMS-7,9, has alternating mesogen and spacer structure with dihydroxy-[alpha]-methylstilbene as mesogen and two different lengths of alkyl spacers ([...] and [...]). A range of molecular weights were prepared to probe the effects of chain flexibility (ratio of chain length of persistence length). Synthesis was scaled up to provide adequate quantities for physical studies (rheology, rheo-conoscopy and rheo-WAXS).
The director response of a monodomain during shear flow is followed by in situ optical conoscopy using a custom-made shear cell. We observe that the director rotates opposite to the vorticity in shear for DHMS-7,9 using planar monodomain samples, demonstrating conclusively that it is flow aligning throughout its nematic temperature range. Director rotation is solely a function of applied strain, independent of shear rate, showing that the Leslie-Ericksen theory is applicable to polymeric nematics for shear rates that are low relative to their molecular relaxation. Comparisons of the observed tumbling parameter of DHMS-7,9 with predictions from available molecular models lead us to infer that molecular flexibility produces shear alignment for this class of thermotropic LCPs. To identify the effect of chain flexibility on the dynamics of this LCP, the rotational viscosity and shear viscosity were measured as functions of molecular weight. Both viscosities showed weaker sensitivity to molecular weight above a characteristic molecular weight, suggesting a crossover to semiflexible character at high molecular weight.
Rheology and shear orientation behavior of DHMS-7,9 are markedly different from that of nematic lyotropic LCPs. Synchrotron WAXS measurements in steady shear show that molecular orientation is relatively high and nearly independent of shear rate. In transient shear during flow inception, flow reversal, and step up/down shear rate, neither shear stress nor orientation parameter shows multiple oscillations. Thus, both steady and transient responses of DHMS-7,9 are characteristic of flow-aligning liquid crystals, in contrast to tumbling rod-like LCPs, which show complex shear rate dependence in steady shear and oscillatory response to these transient flows.
An interesting feature of DHMS-7,9 is the existence of a mysterious liquid crystalline phase--Phase X. The flow behavior of Phase X is completely different from that of the nematic phase. A striking flip of the orientation from the flow direction to the vorticity direction occurs below a critical shear rate. This orientational flipping is reversible in response to step changes of temperature and/or shear rate. In addition, we found that oscillatory shear flow also induces a similar type of orientational flipping. Examination of the linear viscoelastic properties as a function of orientation in Phase X suggests rheological similarity to layered fluids.
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Yang, kai-neng, and 楊凱能. "Dielectric and Photochromic Behavior in Comb-Shaped Liquid Crystalline Polymers Containing Azobenzene Side Group." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/04889805312042203409.
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碩士輔仁大學
化學系
88
Abstract Photochromic dye molecules (Such as azobenzenes) change their molecular shape upon photo irradiation, and this property has been used extensively to control the orientation of liquid crystals by light. Besides, azobenzene liquid crystals have been developed, in which the azobenzene moiety plays roles as both mesogens and photosensitive chromophores. The trans form of azobenzene derivative is rod-like, which stabilizes the LC phase, whereas the cis form is bent and destabilizes the LC phase when it is present. Therefore, the trans-cis photoisomerization of azobenzene in the LC phase can cause disorganization of the phase structure. In addition, the cis-trans back-isomerization can take place either by a thermal process or a photochemical process. All these properties enable the comb-shaped side-chain LC polymer (SCLCP) containing an azobenzene moiety a promising material for optical switch and image storage. This study synthesized six SCLCPs of this type in which the azobenzene moiety was attached with different electron-withdrawing group (i.e.,-NO2,-CN,-COCH3) on the para position, and the soft spacer used was either (-CH2-)3 or (-CH2-)9 segment. All their structure were characterized by GPC, NMR, IR, UV, DSC, TGA and POM. All there SCLCPs were stable up to 250℃, and exhibited some stable mesophases (mostly Smectic phase), as confirmed by POM and DSC observations. Photoirradiation was performed with a 100W high-pressure Hg lamp. The change in transmittance of 365 nm absorbance band (corresponding to π-π* transition of trans-azobenzene) was monitored as a function of irradiation time. These results showed that the spacer length and electron-withdrawing capability were the two factors which enhancing the backward isomerization processes, but not for the forward trans-cis isomerization process, Dielectric relaxation studies exhibited a more clear-cut picture for the mesophase transitions of these SCLCP than that of DSC and POM showed. The two factors mentioned above also affects the location of occurrence of β-relaxation.
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Tasi, Yi-Chan, and 蔡易展. "Phase Behavior and Thin-Film Properties for Solution-Processed Field-Effect Transistor Based on Liquid-Crystalline Semiconductor Oligothiophenes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/99562959154036285179.
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碩士國立暨南國際大學
應用化學系
98
In view of the increasing popularity of Organic Field Effect Transistor（OFET）. In order to implement the industrialization process, therefore, the solution process becomes an important of development goals. In this study, we used highly-soluble oligothiophene derivatives as organic active layer. These thin film were deposited by vacuum evaporation and solution process. In the vacuum evaporation process, we previous used to modify substrate surface by self-assembled monolayer（SAM）, octadecyltrichlorosilane（ODTS） and Hexamethyldisilazane（HMDS）. Then, rubbing to further improve the arrangement of SAM. The results of this series of results to that NTETB has the best electrical properties, the carrier mobility of up to 3.51×10-2 cm2/Vs and on/off current ratio is 4.04×102. Then, by atomic force microscopy and X-ray diffraction to investigate the relationship between film morphology, molecular arrangement and electrical property. Also because NTETB have the best performance, so a precursor of solution process in this study. After optimizing the conditions of the thin film, the carrier mobility of up to 5.79×10-2 cm2/Vs, but the leakage current was found. Then, using Differential Scanning Calorimeter（DSC） to measure the physical properties and through various heat treatment process. Finally, we analyze the thin film phase change process by polarized optical microscope and X-ray diffraction.
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Shih, Yuh-Jinn, and 施裕進. "Synthesis and Mesomorphic Behavior of Thermotropic Side Chain Liquid Crystalline Polysiloxanes Containing an Oligo ( ethylene glycol ) Monomethyl Ether-Substituent." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/94138504311259099036.
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Wei-HanChang and 張維瀚. "Calorimetric Study of the Additive Effects on the Gel to Liquid-Crystalline Phase Transition Behavior of Catanionic Bilayer Membrane." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/46008407079786464985.
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碩士國立成功大學
化學工程學系碩博士班
100
Four ion pair amphiphiles(IPAs) of different hydrocarbon chain lengths with symmetric and asymmetric hydrocarbon chains were prepared from cationic and anionic surfactants by the precipitation in this work. By using differential scanning calorimetry(DSC), the thermotropic transition behavior from gel to liquid-crystalline state was measured for bilayer membranes of these lipid-like catanionic surfactants. Moreover, the effects of additives(cholesterol, vitamin E, and vitamin E acetate) in catanionic bilayer membranes on phase transition temperature, enthalpy change and entropy change were determined. The experimental results showed that the phase transition temperature is higher for catanionic surfactants with higher total carbon number in the hydrocarbon chains. And for the catanionic surfactants with the same total carbon number in the hydrocarbon chains, the phase transition temperature is higher for the symmetric one than that with asymmetric one. No consistent trend in enthalpy changes, however, was exhibited by the different catanionic surfactants. With the addition of cholesterol, vitamin E, and vitamin E acetate in the bilayer membrane of catanionic surfactants, the phase transition temperatures were found to be unaffected. On the other hand, the enthalpy and entropy changes decreased with the increase of these three additives.
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Chen, Wen-Ren, and 陳文仁. "The research on the phase behavior and optical-electro properties in the (nematic/discotic) and (nematic/chiral dopant) liquid-crystalline composite system." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/94275100733319875743.
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博士元智大學
化學工程學系
93
Two binary liquid-crystalline composite systems were composed of (a nematogen and a discotic mesogen) and (a nematogen and a chiral dopant). The phase behaviour and optical-electro properties of two binary composites have been investigated. The former system yielded an induced SmA phase in the range of 80/20~30/70 wt.%. The layer-stacking structure of binary composite was proposed in the SmA phase. The latter system formed N* phase in the S811 content under 20 wt.%. The frusted phases, BP and TGBA*, and the SmA* phases were formed in the range 25~30% and 40~80%. The orientational ordering of the binary composites increased with increasing the chiral dopant content and decreasing sample temperature. The optical-electro properties were also investigated under the external electric field.
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ZHANG-JIAN, GUO-PING, and 張簡國平. "Synthesis､molecular micro-structure and mesomorphic behavior of terminally carboxyl oligo (ethylene oxide) monomethyl ethers-substituted side chain liquid crystalline polysiloxane and copolysiloxane polymers." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/98239961271486733827.
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Chou, Yen-Ling, and 周彥伶. "Synthesis and Optical Behaviors of Novel Ternary Liquid Crystalline Copolymers." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/76572301030679792974.
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碩士國立成功大學
化學工程學系碩博士班
96
In order to investigate the effect of temperature and UV irradiation on the reflective band of cholesteric liquid crystals, a series of novel side chain liquid crystalline binary (P1 and P5) and ternary (P2~P4 and P6~P8) polymers consisting of one (N=N or C=C) or dual (N=N and C=C) photochromic segments were synthesized and characterized considering their liquid crystalline, optical, and photochromic properties and their thermal stability. Monomers were polymerized with various feed compositions under the same conditions. The synthesized polymers, P1-P8, were identified using FT-IR, NMR, and EA. Thermal and optical properties were estimated using DSC, TGA, XRD, and POM instruments. Molecular weight of polymers was calculated to be between 7.0 x 103 and 1.5 x 104. Thermal resistance was found to be higher than 300oC. An increase of temperature was found to cause a blue shift of reflective band. Polymer P1 revealed highly thermal sensitivity. It is expected to be used as a thermal sensor. Contrary to that, introduction of a chlorine atom onto benzene ring of liquid crystal molecule reduced hermal sensitivity of polymer’s reflective band. For polymer P5, variation of the reflective band was limited between 400 and 450 nm. Polymers synthesized in this investigation are expected to be used as novel materials in the field of thermal sensing and color image recording techniques.
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Li, Jiong-Xian, and 李炅憲. "Pretransitional Behaviors from the Isotropic to Liquid Crystalline Phase of Liquid Crystals Confined in Cells." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/kv55hm.
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碩士國立交通大學
光電科技學程
107
The purpose of this study is to adopt dielectric spectroscopy to observe the change of optical textures and dielectric behaviors of liquid crystals (LCs) injected into sandwich-type cells with distinct types of spacers (rod and ball) during the isotropic to LC phase transition. It is found that the spacer will lead to a textural formations and generate a pretransitional (PT) phase for both rod- and ball-spacer-contained LC cells without affecting their dielectric constants. In order to confirm the effect of spacer on observed results, we also fabricated a counterpart in which there is no spacer in the electrode area. The results indicated that the PT phase is absent in the no-spacer LC cell and the regularity of the dielectric constant is different from those of cells with spacers (rod type). On this basis, the dielectric properties and textural transitions of various nematic LCs, including CYLC31 and HDE with positive dielectric anisotropy (+∆) and MLC6608 and ZLI2806 with negative dielectric anisotropy (–∆) injected in rod-spacer-contained cells. The result shows that the regularity of dielectric spectrum changed as a function of the temperature is affected by the magnitude of ∆, In other words, the larger ∆ of positive LCs in rod cells will lead to the induction of PT phase easier. Finally, we investigate the formation of PT phase in spacer-contained CLC cells by doping various contents of chiral agent R5011 in nematic host E44. By dielectric spectrum and textural observation result, it shows that the dielectric signal for the determination of the PT phase in the ’(T) becomes intense and the clearing temperature point gets decreased with increasing dopant concentration of R5011 in E44. As a result, we conclude that the generation of PT state in spacer-contained LC cells is determined by the magnitude of ∆ and the texture formation is affected by the shape of spacer.
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Wei-ChiehChen and 陳偉杰. "Synthesis and Photo-Behaviors of Amphotropic Liquid Crystalline Monomer with Cholesteryl Group." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/61121663652426229454.
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碩士國立成功大學
化學工程學系
102
In this work, we synthesized a liquid crystalline monomer CCM, which possess amphotropic liquid crystalline properties. Dependence of selective reflection on molecular arrangement and temperature effects were studied. Furthermore, a novel diblock copolymer PS-b-PCCM was synthesized via ATRP method and a homopolymer PCCM was synthesized using AIBN. The amphotropic liquid crystalline monomer CCM shows thermotropic cholesteric liquid crystal phase at a temperature higher than 90°C. Lyotropic cholesteric liquid crystal state exists in some proper solvents. Increase of temperature to a specific point, some CCM monomers were found to be polymerized. The partially polymerized cholesteric liquid crystal shows some higher order and more significant selective reflection. The results of lyotropic liquid crystalline CCM suggest that this predesigned CCM is available for using as a solvent sensor and tunable bandgap filter.
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Yun-ChiehSung and 宋昀潔. "Optical Behaviors of Cholesteric Liquid Crystalline Polyester Composites with Various Chiral Photochromic Dopants." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/79839908142666583237.
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碩士國立成功大學
化學工程學系碩博士班
98
To investigate the induction of photonic arrangement using chiral photochromic dopants, a series of novel chiral photochromic dopants and main-chain liquid crystalline polyesters were synthesized. The molecular structure of the synthesized compounds was identified using NMR, FTIR, and elemental analyses. Phase transition temperature and the liquid crystal phase determination of the synthesized polymers were estimated using DSC, WAXD and POM analyses. Furthermore, to investigate the dependence of UV light irradiation on incident reflection band, we mixed main-chain liquid crystalline polymers with chiral photochromic dopants to form the liquid crystalline polymer blends. The influence of dopant concentration and the solubility in liquid crystalline polymer blend were also studied. Due to the photochemical reaction of the chiral photochromic dopants, the reflection band of the cholesteric liquid crystalline polymers could be adjusted and tuned at visible light region. A real image recording of chiral photochromic liquid crystalline polymer blend was achieved by exposing UV light through a mask.
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Yeh, Ming-che, and 葉銘哲. "Design and Synthesis of the Discotic Liquid Crystalline Materials for Controlling Mesomorphic Behaviors and Supramolecular Assembly." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/85630693117595133196.
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博士國立中山大學
化學系研究所
101
Discotic liquid crystals (DLC) have been reported with a large number of discoid cores to improve the degree of intermolecular ordering because the liquid crystals own to self-assembly into columnar stacking and self–healing ability. In my research, a series of disc-like π-conjugated molecules based on aromatic rigid cores have been newly synthesized. I focus on the hexaazatrinaphthylene (HATN) and dibenzo-[a,c]- phenazine as aromatic cores, changing different side chains to control the mesomorphic behavior and their supermolecular assembly.