Liquid Crystal Polysiloxanes Research Articles

Synthesis and Characterization of Novel Ferroelectric Liquid Crystal Polysiloxane Containing Undecanoyloxy Spacer (I)

A novel side-chain liquid crystal polysiloxane and its corresponding monomer were synthesized by the standard method. We ensured their structures were as expected and their purities were high by 1H nuclear magnetic resonance and infrared measurements. They were studied by differential scanning calorimetry (DSC) for their thermal analysis and polarizing optical microscopy (POM) with hot stage for their textures and transition temperatures. The results showed good liquid crystal properties and low transition temperatures of the mesophase. X-ray diffractions were done to research their layer structure and SmA and SmC* phases were assured, in good agreement with the results of the POM and DSC measurements. The optical rotation degree was also measured.

Synthesis and Characterization of Novel Ferroelectric Liquid Crystal Polysiloxane Containing Undecanoyloxy Spacer (I)

A novel side-chain liquid crystal polysiloxane and its corresponding monomer were synthesized by the standard method. We ensured their structures were as expected and their purities were high by 1H nuclear magnetic resonance and infrared measurements. They were studied by differential scanning calorimetry (DSC) for their thermal analysis and polarizing optical microscopy (POM) with hot stage for their textures and transition temperatures. The results showed good liquid crystal properties and low transition temperatures of the mesophase. X-ray diffractions were done to research their layer structure and SmA and SmC* phases were assured, in good agreement with the results of the POM and DSC measurements. The optical rotation degree was also measured.

Synthesis and Characterization of Novel Ferroelectric Liquid Crystal Polysiloxanes Containing Undecanoyloxy Spacer (II)

The synthesis of two novel side-chain liquid crystal polysiloxanes (IP and IIP) containing 4-[(s)-2-methyl-butoxy] biphenyl or 4-[(s)-2-methyl-butoxy] biphenyl benzoate moiety as mesogenic units, respectively, and an aliphatic spacer containing undecanoyloxy units is presented. Differential scanning calorimetry, polarizing microscopy and X-ray diffraction measurements revealed chiral smectic mesomorphism for the two polymers. Both polysiloxanes IP and IIP exhibit smectic A and chiral smectic C* phases. Among the corresponding monomers prepared in this study, the 4-[(s)-2-methyl-butoxy]biphenyl 10-undecylen-1-ate shows smectic A and chiral smectic C* phases, but the 4-[(s)-2-methyl-butoxy] biphenyl 4-(10-undecylen-1-yloxy) benzoate reveals only smectic B, smectic A and cholesteric phases. The results seem to demonstrate that the tendency toward glass, and also that melting temperature (Tm) and isotropic temperatures (Ti) of liquid crystal, mesomorphic ranges (ΔT) and thermal stability in both polymers and monomers increase with increasing the rigidity or the number of the benzene ring or length versus diameter value of mesogenic moieties (L/D) value of mesogenic moieties. The Ti and ΔT of polysiloxanes containing the undecanoyloxy spacer are lower than those containing the undecyloxy spacer on using the same mesogenic moiety. Polymerization generated a smectic phase and led to higher liquid crystal and isotropic transition temperatures; also the liquid crystal ranges were broadened and more ordered phases were formed comparing polymers with monomers, respectively.

Synthesis and characterization of side-chain liquid crystalline polysiloxanes

The synthesis and characterization are described for a series of side-chain liquid crystal polysiloxanes using polyhydrosilylation reaction between a poly(hydrogen methyl-co-dimethylsiloxanes),-(OSiHMe)x,-(OSiMe2)y-, where x/y was 13/87, 30/70, 55/45, 73/27 and 98/2, and [4-(allyloxy)benzoyll biphenyl mesogenic group. The side-chain liquid crystal polysiloxanes were characterized by1H NMR,13C NMR, IR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and optical polarizing microscopy. The dimethylsiloxane segment factors governing thermal transition temperatures and activation energy (Ea) of the nematic-to-isotropic phase transition are discussed.

Some relevant parameters on the ‘jacketed’ effect in side-on fixed polysiloxanes

Abstract New ‘side-on’ attached liquid crystal polysiloxanes have been synthesized with different fixation ratios of side groups and various degrees of polymerization. For these syntheses, a series of random copoly(hydrogenmethyl-dimethylsiloxane)s, used a precursors, has been realized. Both thermal properties and small angle neutron scattering experiments on these polymers show a decrease in the nematic ‘jacketed’ effect as the number of mesogenic groups fixed to the backbone decreases and as the main chain length increases.

Isomer specific analysis of PCDD/F by HRGC-MS using polymeric liquid crystal stationary phases

Four different side chain liquid crystal polysiloxanes were synthesized and evaluated as stationary phases for dioxin and furan analysis, focusing on isomer specific separations and analysis of those containing substitution at positions 2,3,7 and 8. The selectivities of the stationary phases were found to vary according to their mesophase range and degree of order of the liquid crystalline lattice. Reproducibility was investigated by testing three separate batches of one of the products.

Liquid crystal side chain polysiloxanes containing various proportions of non-mesogenic units

Abstract Recent studies have established that side chain polymeric liquid crystals composed of mesogenic and non-mesogenic side groups keep their liquid-crystalline properties even for a low proportion of mesogens. We show that the detailed structures of three kinds of new diluted liquid crystal polysiloxanes depend on the nature of the co-substituent as well as on the proportion of the silicon sites occupied by the mesogenic groups. Mixtures of these systems with low molar mass liquid crystals were also investigated in terms of compatibility and/or stabilization of smectic A phases.

Synthesis and Properties of Some Liquid Crystal Polysiloxanes with Laterally or Terminally Attached Side Chains

Abstract A series of polysiloxanes having laterally-attached mesogenic side chains and involving variations in spacer length and the nature of the two end groups are reported. The terminally-attached analogues of some of these polymers are also reported. Optical microscopy and differential scanning calorimetry were used to establish the mesomorphic properties. An explanation is proposed for the low TN-1 values observed for the polymers with laterally attached side chains.

A polymeric liquid crystal capillary column for GC‐MS analysis of PCDD and PCDF

AbstractA newly developed side chain liquid crystal polysiloxane has been investigated as a stationary phase for the isomer‐specific analysis of polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans substituted at positions 2, 3, 7, and 8. The retention times from the chromatograms of a standard solution containing all PCDD and PCDF isomers were compared with those from solutions containing only those tetra‐ to octa‐chlorinated compounds substituted at positions 2, 3, 7, and 8. In general, PCDDs substituted at positions 2, 3, 7, and 8 eluted later than most other isomers of the same congener group. The separations obtained on this stationary phase were compared with those obtained elsewhere using a commercially available product.

Photochromism of side-chain liquid crystal polymers containing spironaphthoxazines

Abstract Side-chain liquid crystal polyacrylates and polysiloxanes containing different photochromic spironaphthoxazine side groups were synthesized. Thermodynamic, spectral and kinetic properties of the polymers were investigated. The structure of the mesophase is discussed.

Carbon-13 NMR investigation of molecular order in liquid crystal polysiloxanes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 NMR investigation of molecular order in liquid crystal polysiloxanesH. Oulyadi, F. Laupretre, L. Monnerie, M. Mauzac, H. Richard, and H. GasparouxCite this: Macromolecules 1990, 23, 7, 1965–1971Publication Date (Print):April 1, 1990Publication History Published online1 May 2002Published inissue 1 April 1990https://doi.org/10.1021/ma00209a015RIGHTS & PERMISSIONSArticle Views63Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (785 KB) Get e-Alerts Get e-Alerts

An X-ray diffraction study of a chromophoric liquid crystal polysiloxane

Abstract Polymeric materials of composition, where a = 0.54, b + c = 0.46 and c = 0.000, 0.029, 0.059, 0.107, 0.234 have been characterized using X-ray diffraction and found to have bilayer S A structures. The smectic layer spacing of 39 A at 20°C was found to decrease by 0.04 A K−1 with increasing temperature for all the materials.

Liquid crystal polymers containing macroheterocyclic ligands. 2. Side chain liquid crystal polysiloxanes and polymethacrylates containing 4-(.omega.-alkan-1-yloxy)-4'-(4'-carboxybenzo-15-crown-5)biphenyl side groups

Preparation de polymethacrylate par polymerisation radicalaire du monomere corespondant et de polysiloxane par hydrosilylation de l'alcene correspondant par le poly (methylsiloxane). Les polymeres obtenus presentent les mesophases enantiotropes smectiques et nematiques alors que les monomeres ne montrent que des mesophases monotropes

Effect of Molecular Structure on the Properties of Schiff's Base Side-Chain Liquid Crystal Polysiloxanes

Abstract A series of smectic liquid crystal polymers with a polysiloxane backbone and Schiff s base side-chains is presented. In a three-step procedure, hydroxy-terminated Schiff s bases were first prepared and then converted to allyloxy-terminated derivatives. Only few of the resulting monomers were liquid crystals, even though all were potentially mesomorphic. When attached to a polysiloxane backbone via a 3-carbon spacer, all resulting polymers were smectic. Where comparisons were possible, the mesophase ranges for the polymers were greater than those for the corresponding side-chain precursors. Interesting trends were observed in the effect of the length of the alkyl and alkoxy terminal substituent on the liquid crystal properties. The chloro-terminated side-chain precursors did not exhibit liquid crystal properties, but gave the widest mesomorphic range polymers. The high transition enthalpies for the mesomorphic-isotropic transition are indicative of a smectic mesophase. The transition temperatures and entropies for the smectic-isotropic transitions for an alkoxy terminated series show odd-even alternations.

29Si N.M.R. investigations of polysiloxanes

Abstract A number of side chain liquid crystal polysiloxanes prepared from both homo-and co-polymeric backbones have been studied by 29Si N.M.R. and the chemical shifts assigned. Partly mesogenated poly(hydrogenmethylsiloxanes) have been similarly studied and chemical shift assignments made for sequence distributions. The data should prove helpful in studies of compositional variation in preparations of side chain copolymeric polysiloxanes.

Side chain liquid crystal polysiloxanes and their low Tgcopolymer analogues

Abstract A number of side-chain liquid crystal homopolymers derived from poly-(hydrogenmethylsiloxane) and their copolymeric analogues with the same mesogenic side chains appended to a poly(hydrogenmethyldimethylsiloxane) backbone have been prepared. The homo and copolymers exhibit the same mesophase types, but markedly different Tg values, mesophase transition temperatures and isotropisation enthalpies. These differences are interpreted in terms of the relative DP values and flexibilities of the backbones for the homo and copolymers.