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Topic: Mesogens

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Columnar phase

Liquid crystal

	Solvated mesophase pitches - Patent 5259947
		Solvated mesophase pitch having liquid crystalline structure comprising a solvent in mesogens, pseudomesogens or mixtures thereof wherein the solvated mesophase pitch is at least 40 volume percent optically anisotropic and wherein the solvated mesophase pitch melts at least 40.degree.
		The present invention is solvated mesophase comprising a solution of solvent in mesogens or pseudomesogens wherein the solvated mesophase is at least 40 percent by volume optically anisotropic and wherein the solvated mesophase melts at least 40.degree.
		Mesogens are then recovered from the rejection mixture as a powder by filtration in conventional solvent fractionation.
	www.freepatentsonline.com /5259947.html (8479 words)

	Academic and Research Archive
		1.N.K.Chudgar, S.N.Shah and R.A.Vora, "Mesogenic semicarbazones and amino oxadiazoles - I", Mol.
		2.N.K.Chudgar and S.N.Shah,"New fluorescent mesogens with a chalcone linkage”, Liq.
		8.N.K.Chudgar, Vandana Shah and S.N.Shah, "Synthesis and characterization of new mesogenic phenylhydrazones, Mol.
	orca.st.usm.edu /~snshah/ARARCIVE.html (2146 words)

	Conducting liquid crystals - Patent 5370820
		The mesogens from which the novel liquid crystals of this invention may be produced are those thermotropic mesogens which are capable of forming a radical salt, i.e.
		The radical salts of the mesogens may be formed by doping the mesogen with an oxidizing or a reducing agent.
		The dopant used to form the radical salt of the particular mesogen is preferably one which is miscible with the mesogen; at least in the quantity which is to be employed.
	www.freepatentsonline.com /5370820.html (2077 words)

	OhioLINK ETD: Pugh, Coleen
		In addition to the symmetrically substituted, linear 1,2-(4,4′-di-n-alkyloxyphenyl)acetylenes, diarylacetylenes with both symmetric and asymmetric methyl branches in either the alkyloxy substituents or in the aromatic ring(s) of the mesogen were examined, as well as extension of the mesogens by one phenylethynyl unit.
		However, if the mesogen is extended by one phenylethynyl unit, destabilization of liquid crystallinity by the small fluorine substituents is compensated by the large length to bredth ratio of the mesogen.
		The reaction was also used as an in situ mesogen forming polymerization reaction to form branched polymers with disc-like mesogens.
	www.ohiolink.edu /etd/view.cgi?case1059486231 (367 words)

	lcsandpolymers
		If the long axes of the mesogens are arranged parallel to the layer normal, the phase is called smectic A. In the smectic C phase the molecules are tilted (Figure 1).
		Polymers with mesogenic units in the main chain have high melting points and often decompose before they reach the clearing temperature(7).
		If the mesogenic units are in the side chain, the polymers behave similar to low molar mass compounds, concerning mobility and phase sequence.
	www.uni-koblenz.de /~mbrehmer/P99-2.htm (999 words)

	SPIE Proceedings Vol. 3319
		Abstract: IR spectroscopy was used to analyze the orientation behavior and in-situ photopolymerization of two mesogenic acrylates in the chiral smectic I phase and in the S$-A$/ phase, respectively.
		The mesogens have a bulky lateral branch containing an aromatic ring with an alkenyl chain in para- position, which enables a coupling to the polysiloxane backbone.
		Although, the rather flexible spacer between the mesogenic group and the main chain seems to be sufficient to partially decouple the mobility of the main chain from that of the mesogenic group, the influence of a backbone chain structure is still significant for polymer properties, especially in bulk.
	www.spie.org /web/abstracts/3300/3319.html (9080 words)

	myelections.com Liquid crystal
		Disk-like (discotic) mesogens are also known, and these orient in the direction of their short axis.
		For instance, a particular mesogen may exhibit various smectic and nematic (and finally isotropic) as temperature is increased.
		In the smectic A phase, the molecules point perpendicular to the layer planes, whereas in the smectic C phase, the molecules are tilted with respect to the layer planes.
	www.myelections.com /certifications.htm (1266 words)

	An x-ray scattering study of liquid crystalline elastomers
		Liquid crystalline elastomers are a class of new materials which combine the elasticity of elastomers and the orientational alignments of liquid crystals.
		We have performed X-ray scattering and strain measurements to study the structural and mechanical behaviors of a series of liquid crystalline elastomer samples which were synthesized with a one-step photopolymerization method.
		We found that the percentage of mesogens in the nematic phase showed a similar trend as the nematic order parameter with increasing temperature.
	repository.upenn.edu /dissertations/AAI3165773 (329 words)

	Vance Williams
		Although these "discotic mesogens" have been extensively studied since their discovery almost thirty years ago, little is known regarding the relationship between the structure of a molecule and its tendency to assemble into columnar nanostructures.
		This research has also led us to examine the properties of mesogens that are elliptical rather than disc-shaped.
		We are continuing to pursue the design of new "ellipsotic mesogens" that are created from disc-shaped molecules linked together either by hydrogen bonds, metal coordination or covalent bonds.
	www.sfu.ca /~vancew/vewresearch.htm (417 words)

	Thermotropic Polypeptides Bearing Side-On Mesogens (Site not responding. Last check: 2007-10-20)
		Here, we have laterally coupled (side-on) thermotropic mesogenic groups to lysine residues to prepare polypeptides that form thermotropic liquid crystalline phases where packing requirements of both polypeptide and mesogenic groups are satisfied.
		When biphenyl mesogens were attached end-on to poly(glutamate) side chains via six carbon alkyl spacers, layered structures were observed in the crystalline and liquid crystalline states, followed by transition into a cholesteric structure at higher temperatures.
		By varying the length of aliphatic linker between the polypeptide backbone and the mesogen, we were able to tune both the temperature of the melting transition and the degree of ordering of the rodlike polypeptides in the liquid crystalline nematic state.
	pubs.acs.org /cgi-bin/sample.cgi/mamobx/2006/39/i01/html/ma052127k.html (2090 words)

	Liquid crystal - Wikipedia, the free encyclopedia
		Thermotropic LCs exhibit a phase transition into the LC phase as temperature is changed, whereas lyotropic LCs exhibit phase transitions as a function of concentration of the mesogen in a solvent (typically water) as well as temperature.
		For molecular mesogens, this means that the molecule must possess an asymmetric carbon atom.
		In this aligned state, the mesogens do not reorient light, so the light polarized at the first polarizer is absorbed at the second polarizer, and the entire device appears dark.
	en.wikipedia.org /wiki/Liquid_crystals (3030 words)

	McGrath Research Group
		My research project is an investigation of the scope of azobenzene chromophores acting as liquid crystalline mesogens.
		Azobenzene chromophores are calamitic mesogens, yet have been incorporated into dendrimers to effect size and property changes.
		We are particularly interestedin the interplay between the mesogenic properties of the azobenzene chromophore and the self-organizing capabilities of amphiphilic dendrimers.
	www.chem.arizona.edu /mcgrath/Website/Student_Pages-withinfo/SBiswas.cfm (55 words)

	Introduction to Liquid Crystal Polymers
		The mesogen acts just like the stiff areas in the first group, but are comprised of two or more aromatic rings, which give the necessary restriction for the polymer to display its liquid crystalline properties.
		The mesogen is commonly comprised of a rigid core of two or more aromatic rings joined together by a functional group.
		The spacer: mesogens that are attached to the backbone of a side chain PLC are able to orient themselves due to the fact that the spacer allows for independent movement.
	www.eng.buffalo.edu /~pascoe/lcp/joe (1264 words)

	Department of Chemistry
		Liquid crystalline star polymers contain mesogenic or rigid groups attached to a central cyclic core.
		The focus in our labs is to synthesize LC star shaped materials containing mesogenic groups eminating from a cyclic siloxane core.
		In this study the “core-first” method is employed to prepare 4-arm star materials via ATRP of mesogens derived from cinnamic acid.
	www.has.vcu.edu /che/people/bio/ruder.html (423 words)

	monoFunc_txt.html
		Although this mixture is mesogenic at room temperature, the clearing point has also been greatly reduced, thus indicating a shift of mesogenic range to lower temperatures rather than a true overall enhancement.
		Every new mesogenic triphenylene derivative shows a depression in the melting point and a substantial broadening of the LC temperature range relative to the parent compound 1.
		This is reasonable considering the conformational preference of alkyl chains attached to phenyl rings to reside perpendicular to the plane of the ring and thus out of the plane of the molecular disk.
	www.csupomona.edu /~jarego/pages/monofunc.html (4567 words)

	OPUS - New fluorene based materials for organic electronics
		The orientation of the crosslinked reactive mesogens on top of rubbed polyimide layers results in a maximum orientation ratio of 15/1 parallel and perpendicular to the rubbing direction.
		This process was investigated by PhotoDSC measurements on two different mesogens, one with a nematic and one with a smectic mesophase.
		The kinetics of the photopolymerisation reactions and the total conversion in dependence from initiator concentration of the reactive mesogen with the nematic mesophase were measured.
	opus.ub.uni-bayreuth.de /volltexte/2005/189 (1345 words)

	Seminar Series
		Formed by cross-linking a polymeric fluid consisting of chains to which nematic mesogens are attached as pendant side-groups or directly incorporated as spacer elements, a nematic elastomer is a rubber-like analogue of a nematic liquid-crystalline fluid.
		The coupling between the orientation of nematic mesogens and the distortion of the polymer network that results from such molecular architectures endows nematic elastomers with novel mechano-optical properties.
		The first successful synthesis of a nematic elastomer was reported in 1981.Subsequent advances in synthesis have led to smectic and cholesteric elastomers.
	www.unl.edu /emhome/seminars/2003-04/EFried.html (340 words)

	Synthesis of Lamellar Mesostructures with Nonamphiphilic Mesogens as Templates (Site not responding. Last check: 2007-10-20)
		Magnesium- and zinc-based lamellar mesostructures were synthesized with nonamphiphilic mesogens as templates.
		Interactions between the template molecules and the inorganic layer were evident through the increase in their decomposition temperatures as compared to the pure template and by the slight weakening of the C=O bond as determined by the IR measurements.
		The synthesis of lamellar mesostructures with nonamphiphilic mesogens broadens the scope of the so-called "liquid-crystal template mechanism" in the sense that it is not limited to amphiphilic molecules but applies also to other molecules which can form large molecular assemblies in solutions.
	pubs.acs.org /cgi-bin/abstract.cgi/cmatex/1996/8/i11/abs/cm950532s.html (240 words)

	Side-Chain Liquid Crystalline Polymers (Site not responding. Last check: 2007-10-20)
		These polymers consist of some type of liquid crystalline molecule (called a mesogen) attached to the polymer backbone though a spacer chain that is typically a few carbon atoms long (Scheme 1).
		Notice that the difference between the nematic mesophase and the smectic C mesophase is that the smectic C mesophase has layered ordering in addition to the ordering of the mesogens in the nematic phase.
		Well, if you examine the pictures of the mesophases in Scheme 1, you might see that if we were to make the mesogens interact in some way, they might be inclined to form layers.
	www-personal.umich.edu /~akiste/sclcp.html (572 words)

	UW NSEC - Tailored Mesogens for Lytropic Liquid Crystal Formation.
		UW NSEC - Tailored Mesogens for Lytropic Liquid Crystal Formation.
		This project focuses on the design and characterization of helical B-peptides as mesogens for liquid crystal formation in aqueous solution.
		Optical micrographs of aqueous solutions of ?-peptides 1-5 between crossed polarizing filters.
	www.nsec.wisc.edu /NS--Nugget.php?ID=4 (227 words)

	Trifunk TPs Text
		While the asymmetric tribromotriphenylene 4b is also mesogenic, it is interesting to point out that 2a, 2b, 3a, and 3b are all nonmesogenic.
		Comparison of mesogens 4a with 4b, and 8a with 8b reveals a general trend in these mixed tail derivatives.
		This idea is supported by the fact that although the asymmetric tribromo mesogen 4b melts at 104°C when recrystallized from solution, the material does not crystallize from the neat LC phase and remains in a super-cooled discotic phase indefinitely at room temperature.
	www.csupomona.edu /~jarego/pages/TrifunkTP_text.html (1274 words)

	April 15, 2002 Heart Cut (Site not responding. Last check: 2007-10-20)
		Mixtures of mesogens and ionic liquids can be organized into layers exhibiting anisotropic ion conductivity. T. Kato and co-authors combined mesogens (1a–c) and an ionic liquid (2) to produce smectic liquid crystalline (SLC) structures.
		Alignment of the mesogens produces a layer of hydroxyl-group–rich tails, to which the ionic liquids coordinate.
		Ionic anisotropies of more than 3 orders of magnitude were observed in the layered structures; the extent of ionic conductivity in these structures depends on the number of hydroxyl groups in the mesogenic molecules.
	www.acs.org /portal/a/c/s/1/acsdisplay.html?DOC=heartcut\archive\0415_heartcut.html (1003 words)

	IngentaConnect Homostructural two-ring mesogens: a comparison of p-carboranes, b... (Site not responding. Last check: 2007-10-20)
		IngentaConnect Homostructural two-ring mesogens: a comparison of p-carboranes, b...
		Homostructural two-ring mesogens: a comparison of p-carboranes, bicyclo[2.2.2]octane and benzene as structural elements
		Mesogenic properties of diheptyl and diheptynyl derivatives of 12- and 10-vertex bi-p-carboranes have been studied in the pure state and as binary mixtures with a nematic host.
	www.ingentaconnect.com /content/tandf/tlct/1999/00000026/00000005/art00023 (197 words)

	Coating composition with thermally-influenced color - United States Patent 5,691,053
		The two most frequently realized molecular structures are the side-chain LC polymers, in which the mesogenic units are attached chemically as side chains of the polymer backbone, and the main-chain LC polymers, in which the mesogenic units form the polymer backbone or part of the polymer backbone.
		Due to their chemical structure, the main-chain LC polymers belong to the class of high temperature-resistant polymers, which are distinguished by very good mechanical properties such as high rigidity, strength and hardness, which are particularly advantageous when the polymers are used as an exterior paints.
		The reflection wavelength of chiral nematic liquid crystals is determined by the pitch length of the helix formed by the mesogenic groups.
	xrint.com /patents/us/5691053 (4856 words)

	MRI \| Faculty Spotlight on Peter Heaney (Site not responding. Last check: 2007-10-20)
		The polymer chains in a LCE may orient spontaneously in response to changes in temperature and/or stress, leading to phase transitions, shape changes, and discontinuous mechanical properties, as illustrated in Figure 1.
		Three types of LCE are known, differentiated by presence and location of rigid structural units called mesogens.
		In each case, the driving force for spontaneous chain alignment is an orientation-dependent energetic coupling between neighboring chains that exceeds the entropic penalty for alignment, but the molecular basis for this energetic coupling is different in each case.
	www.mri.psu.edu /articles/RonaldHedden_FacSpotlight/index.asp (772 words)

	Matthias_Research (Site not responding. Last check: 2007-10-20)
		Morphology of composit materials made from kolumnar LC mesogens and nano particles.
		Synthesis of potential biaxial nematic mesogens and the investigation of their organisation in LC phases.
		In the serie of symmetric mesogens, molecules with up to five benzoat units per arm were synthesised.
	www.tu-chemnitz.de /chemie/synchem/NKSM/Research_NKSM_EN.htm (559 words)

	Paints and Coatings (Site not responding. Last check: 2007-10-20)
		Compounds with Liquid Crystalline Properties and Coating Binders Based Thereon (RFT-59-62) Polymeric vehicles with liquid crystalline-like properties solvent dispersable polymeric vehicles, formulated coating compositions with liquid crystalline-like properties and a method for imparting liquid crystalline properties to a coating binder.
		Polymeric Vehicle for Coatings (RFT-52-53-58) A polymeric vehicle comprising a modified polymer containing covalently bonded mesogenic groups which provides a coating binder and coating film of high hardness, flexibility, and impact resistance.
		Mesogens and Polymers with Mesogens (RFT-54) Novel mesogens, epoxy resins and the synthesis thereof as well as coating binders for coating compositions.
	ndsuresearchfoundation.org /Paints_and_Coatings.htm (521 words)

	discotics
		Because they show liquid crystal behavior for p-alkoxy is p-hexyloxy and p-heptyloxy, and because it still got one aromatic position available for couplings reactions.
		Kouwer has shown that it is possible to couple mesogens with a spacer molecule to poly(acryloylchloride) with retention of the liquid crystal properties of the mesogen side chains.
		) on to the mesogen precursor: The 1,2,3,4,5,6,7-heptamethylnaphthalene (4a.
	www.home.zonnet.nl /galien8/discotic/discotic.html (1379 words)

	Inorganic Chemistry At The Ohio State University
		Organic polymers and liquid crystals, mesogens, find innumerable applications in our daily life.
		The Chisholm group is exploring the introduction of metal ions into organic polymers and liquid crystals with the intent of making smart polymers and mesogens.
		The metal ions may be present as guests within the organic architecture or they may be present as the organizer of the structural motif.
	www.chemistry.ohio-state.edu /research/division/inorgan/inorga05.html (385 words)

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