115595-28-3Relevant articles and documents
Cholesteric fluorescent liquid crystal polysiloxanes with different liquid crystal side chain lengths—Synthesis and properties
Cong, Yue-hua,Gao, Shang,He, Xiao-zhi,Jia, Ying-gang,Liu, Ze-ping,Meng, Fan-bao,Zhang, Bao-yan
, (2020/07/03)
With polymethylhydrogensiloxane (PMHS) as the main chain, two series side-chain cholesteric liquid crystal polymers (ChLCPs) with different liquid crystal side chain lengths were prepared by hydrosilylation reaction. Then two series of cholesteric fluorescent liquid crystal polymers (FL-ChLCPs) were obtained by etherification reaction. The obtained FL-ChLCPs have both excellent mesomorphic behavior, and great photoluminescent property. We confirmed their chemical structures by FT-IR, and 1H NMR spectroscopy, and found them with excellent thermal stability by TGA. We characterized their mesomorphic behavior and thermal performance by POM, DSC and XRD, and confirmed all the polymers belonged to cholesteric phase. FL-ChLCPs emitted different-intensity fluorescence under UV light, and we found some regularity by PL spectrum.
Synthesis and characterization of liquid crystalline organosiloxanes containing 4-methoxyphenyl 4-(2-alkenyloxy)benzoate
Chen, Cheng-Chih,Lin, Chih-Hung
, p. 1270 - 1274 (2016/04/10)
A series of new organosiloxane liquid crystalline materials based on the 4-methoxyphenyl-4-(ù-alkenyloxy)benzoate as mesogenic units have been synthesized and their mesomorphic and physical properties have been characterized. A series of new disiloxanes and trisiloxanes contain 4-methoxyphenyl 4-(ù-alkenyloxy)benzoate as mesogenic these were synthesized by addition of 4-methoxyphenyl 4-(ù-alkenyloxy)benzoate moiety to pentamethylhydrodisiloxane or heptamethylhydrotrisiloxane catalyzed by platinum divinyltetramethyldisiloxane complex. The thermal properties of this new series of thermotropic liquid-crystalline siloxanes were studied by differential scanning calorimetry and polarized optical microscope. Disiloxane series compounds were not showed any liquid crystal phase. Trisiloxanes series compounds exhibited nematic liquid crystal phase. The siloxane molecule helped to reduce the melting temperature. The thermal properties of the new siloxane series exhibited a pronounced odd-even effect with the length of alkyl segment.
Influence of interim alkyl chain length on phase transitions and wide-band reflective behaviors of side-chain liquid crystalline elastomers with binaphthalene crosslinkings
Wu, Xiaojuan,Cao, Hui,Guo, Renwei,Li, Kexuan,Wang, Feifei,Gao, Yanzi,Yao, Wenhuan,Zhang, Lanying,Chen, Xiaofang,Yang, Huai
, p. 5556 - 5566 (2012/08/28)
A series of side-chain polysiloxane liquid crystalline elastomers, E-Cm (where m is the number of carbon atoms in the interim alkyl groups, and m = 4, 6, 8, 10), with binaphthalene derivatives as crosslinkings, were designed and synthesized. The mesophase
Unsymmetric main-chain liquid crystal elastomers with tuneable phase behaviour: Synthesis and mesomorphism
Amela-Cortes, Maria,Heinrich, Benoit,Donnio, Bertrand,Evans, Kenneth E.,Smith, Chris W.,Bruce, Duncan W.
, p. 8427 - 8435 (2012/01/17)
The synthesis of a new series of polysiloxane-based, main-chain liquid crystal elastomers (MC-LCEs) containing unsymmetric mesogenic units is described. The structure of the mesogenic monomers, spacers and cross-linkers has been varied systematically in order to tune the thermotropic behaviour of the networks. Three unsymmetric mesogens were studied, characterised by having two aromatic rings as the rigid core and two different alkoxy chains. Smectic A or nematic phases were observed, depending on the length of the alkoxy chains. These mesogens were combined with three different spacers, a flexible hexamethyltrisiloxane (S1) and two aromatic bis(dimethylsilyloxy)benzene with the silyl groups disposed para (S2) or meta (S3). To form the MC-LCEs, two cross-linkers were chosen, one flexible 2,4,6,8-tetramethylcyclooctasiloxane (C1) and a rigid, aromatic tris(dimethylsilyl)benzene (C2). The elastomers showed low glass transition temperatures (below 0 °C) and low clearing temperatures (between 30 and 72 °C), as such presenting liquid crystalline properties at room temperature. The transition temperatures could be tuned by a simple choice of the components; for instance, the clearing temperature decreased as aromatic spacers or cross-linkers were introduced. In contrast, the glass transition temperature did not depend on the cross-linker or mesogen used and showed only a small dependence on the structure of the spacer. The phase behaviour of the MC-LCEs was affected greatly by the spacer used and networks containing the trisiloxane spacer systematically exhibited the smectic C phase. The insertion of aromatic spacers favoured the formation of a nematic phase over a smectic phase when the flexible cross-linker, C1, was used. This behaviour was enhanced by the addition of the aromatic cross-linker C3, so that the smectic C phase was suppressed totally and only a nematic phase was observed. The synthesis of the components of MC-LCEs is presented and the structure-thermal properties relationships of the MC-LCEs are discussed.
V-Shaped switching and interlayer interactions in ferroelectric liquid crystals
Petrenko, Alexey,Goodby, John W.
, p. 766 - 782 (2008/02/01)
Linear electrooptic responses in ferroelectric liquid crystals can be achieved via thresholdless switching. The molecular parameters for the design of ferroelectric liquid crystals that may yield a thresholdless response have not been delineated so far. In this article we explore some of the chemical design features that may be utilised in controlling switching processes, and we develop property-structure correlations in order to achieve materials that exhibit thresholdless behaviour. The Royal Society of Chemistry.
Silicon-containing polyphilic bent-core molecules: The importance of nanosegregation for the development of chirality and polar order in liquid crystalline phases formed by Achiral molecules
Keith, Christina,Reddy, R. Amaranatha,Hauser, Anton,Baumeister, Ute,Tschierske, Carsten
, p. 3051 - 3066 (2007/10/03)
Polyphilic molecules composed of a bent aromatic core, oligo(siloxane) units, and alkyl segments were synthesized, and the self-organization of these molecules was investigated. Most materials organize into polar smectic liquid crystalline phases. The swi
Ferroelectric cyclic oligosiloxane liquid crystals
Medeiros, David R.,Hale, Michael A.,Hung, Raymond J. P.,Leitko, Jeffrey K.,Willson, C. Grant
, p. 1453 - 1460 (2007/10/03)
Chiral, smectogenic pendant groups have been covalently attached to cyclic oligosiloxanes by hydrosilylation. These materials and the olefinic compounds from which they were derived exhibit ferroelectric behavior. The mesomorphic range, and in particular
Separation and identification of stereoisomers of a tetrameric side- chain liquid crystalline cyclic siloxane
Mann,Haley,Lacey
, p. 353 - 360 (2007/10/03)
For the first time the four stereoisomers of a tetrameric side-chain liquid crystalline cyclic siloxane have been isolated in a pure state by high performance liquid chromatography. The structure of one of the stereoisomers was confirmed by 1H, 13C and 29Si NMR. The structures of the remaining three stereoisomers were assigned by using evidence from the literature and their liquid crystalline thermal properties. All four stereoisomers and the isomeric mixture exhibited calamitic SmC and SmA phases; no discotic phases were found.
Orientation effects in monodomain nematic liquid crystalline polysiloxane elastomers
Lacey,Beattie,Mitchell,Pople
, p. 53 - 60 (2007/10/03)
A series of monodomain liquid crystalline (LC) elastomers based on a polysiloxane were synthesised. These elastomers were prepared either with one or two cross-linking agents in the presence of a mechanical field. By using the real-time X-ray facility at
Induction of smectic layering in nematic liquid crystals using immiscible components. 1. Laterally attached side-chain liquid crystalline poly(norbornene)s and their low molar mass analogs with hydrocarbon/fluorocarbon substituents
Arehart, Stephen V.,Pugh, Coleen
, p. 3027 - 3037 (2007/10/03)
{5-[[[2',5'-Bis[(4''-(n-(perfluoroalkyl)alkoxy)benzoyl)oxy]benzyl]oxy ]carbonyl]bicyclo[2.2.1]hept-2-ene]s were polymerized by ring-opening metathesis polymerization in THF at 40°C using Mo(CHCMe2Ph)(N-2,6(i)Pr2Ph)(O(t)Bu)2/sub
