Chiral liquid-crystalline polyacrylates from (S)-(-)-2-methyl-1-butanol. Synthesis, mesomorphic properties and light scattering

Merlo, Aloir A.; Ritter, Olga Maria Schimidt; Pereira, Fabiano Vargas; Vieira, Carolina Helena; Silveira, Nádya Pesce da

doi:10.1590/s0103-50532001000200010

Cited by 22 publications

(12 citation statements)

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“…10 Two different polymers having a short spacer with four methylene units but different terminal tails in the lateral mesogenic groups have been studied. In another paper 11 we have described the synthesis, mesomorphic properties and solution behavior of new chiral polyacrylates derived from (S)-2-methyl-1-butanol as chiral terminal chain with spacer groups having either four or eleven carbon atoms. The polyacrylate with four methylene units in the spacer exhibits a chiral nematic phase, whereas the polyacrylate having a spacer containing eleven methylene units displays a smectic phase.…”

Section: Introductionmentioning

confidence: 99%

“…[9][10][11] We selected four compounds having chiral and achiral mesogenic side groups with similar theoretical size but different number of carbons in the spacers and the terminal tail. X-ray scattering was used in order to, firstly allow unequivocal mesophase characterization of the polymers and, secondly, elucidate the local packing of the mesogenic units and the polymer backbones by comparing the experimental X-ray results with those obtained from molecular models.…”

Section: Introductionmentioning

confidence: 99%

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Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

Pereira¹,

Ritter²,

Gonçalves³

et al. 2006

J. Braz. Chem. Soc.

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A influência da estrutura química dos grupos mesogênicos e do tamanho dos grupos espaçadores, no comportamento de fase de uma série de cristais líquidos poliméricos de cadeia lateral (SCLCP), foram estudados utilizando-se espalhamento de raios-X a Baixo Ângulo (SAXS) e Microscopia Ótica de Luz Polarizada (POM). Análises do arranjo das mesofases em amostras não orientadas e orientadas por ação do campo magnético são descritas. O papel do tamanho do espaçador lateral no empacotamento local e na largura da camada esmética determinados nas mesofases SmA e SmC é elucidado. Os ângulos θ formados entre os grupos mesogênicos e a normal às camadas nas mesofases SmC foram determinados. Um estudo a respeito do grau de ordem em função da temperatura, para os polímeros esméticos foi possível através de medidas de SAXS. Uma ordenação particular em um dos SCLCPs estudados é relacionada com a coexistência de duas fases distintas.The influence of the chemical structure of the mesogenic groups and the length of the spacer groups on the phase behavior in a series of side-chain liquid crystalline polyacrylates (SCLCP) have been studied using Small Angle X-ray Scattering (SAXS) and Polarized Optical Microscopy (POM). Analyses of the mesophase arrangement in unaligned and aligned samples by magnetic field are reported. The role of the spacer length on the local packing and on the thickness of the layers encountered in the SmA and SmC mesophases is elucidated. The tilt angles θ of the mesogenic cores related to the normal of the layers in the SmC mesophases are measured. A study about the degree of order as a function of temperature for the smectic polymers was possible using SAXS measurements. A particular arrangement in one of the studied SCLCPs is related to the coexistence of two different phases.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

Pereira¹,

Ritter²,

Gonçalves³

et al. 2006

J. Braz. Chem. Soc.

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“…9 In previous papers, we have reported the synthesis and mesomorphic behavior of a series of chiral liquid crystals polymers with different flexible spacer groups as well as chiral terminal chains. 10,11 The phase behavior was dependent on the molecular relationships among the polymer backbone, the terminal group attached to mesogenic group and the molecular mass. The polymers under analysis consisted of a poly(acrylic acid) backbone, to which the mesogenic units were linked by a spacer group.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, there is a reduction in the specific free volume in the smectic phase when compared with the nematic phase. 10,11 In SmA* environment, there is a partial overlapping of the side chains which contribute to reduction of specific free volume, increasing the Tg. …”

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Synthesis and mesomorphic properties of side chain liquid-crystalline biphenyl-phenyl polyacrylates

Ritter

Silveira

Merlo

2006

J. Braz. Chem. Soc.

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A síntese e a caracterização de dois cristais líquidos poliacrilatos, de cadeia lateral contendo o sistema bifenil-fenila como unidade central são descritos. A cadeia terminal é derivada da L-isoleucina. Em cada caso, o espaçador undecila foi utilizado para conectar o grupo mesogênico e a cadeia polimérica. Ambos os polímeros apresentaram mesofase esmética A. Encontrou-se uma dependência entre as propriedades transicionais e parâmetros estruturais, tais como, flexibilidade da cadeia polimérica e conectividade da cadeia terminal quiral.The synthesis and characterization of two chiral side-chain liquid crystal based on polyacrylates having a biphenyl-phenyl system as a core unit are described. The chiral terminal chain is derived from L-isoleucine. In each case an undecyl spacer was used to connect the mesogenic group to the backbone. Smectic A phase was found for both polymers. The transitional properties were dependent on structural parameters such as backbone flexibility and chiral terminal chain connectivity. Keywords: chiral polyacrylates, L-isoleucine, synthesis, liquid crystal IntroductionLiquid crystals science is a field of human knowledge that emerged at the end of the 19 th century when the Austrian botanist Friedrich Reinitzer 1 reported from his microscopic observation the unusual thermal behavior of the molten sample of cholesteryl benzoate. This first observation of optical anisotropies phenomena in organic compounds opened a new and fascinating class of soft materials which combines extraordinary optical, elastic and viscous properties.Liquid crystals are systems that can self-organize due to mesogenic groups which show short and long range collective interactions among them. This is the origin of interesting liquid crystals properties which were exploited extensively in the earlier 70's in TN-LC technology. 2,3 Nowadays, the LC displays are found everywhere such as watches, clocks, calculators, portable notebooks computers, vehicle clocks, speedometers, navigation and positional aids, mobile phones, flat desktop monitors, wave plates, polarizers, notch filters, etc. The LC technology has dominated the display market due to their compactness, low weight, low-voltage operation, and lower power consumption. In our technological society, LC displays provide an interface between humans and machines and are expected to play an even bigger role in the future as the need of displaying information grows. The need of developing LC materials, batteries, polarizers, electrodes, semi-conductor, compensation films, spacers, etc for those applications mentioned before has been the main driving force behind LC research. LC science growth was dependent on the parallel progress and development of other fields of science such as synthetic organic chemistry, electronics, physics and device engineering.Concerning LC materials, there are basically two types of concepts related to the design and synthesis: (i) development of non-polymeric liquid crystals which are extensively used in LC displays as fast active devices w...

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Activation of C−H⋅⋅⋅Halogen (Cl, Br, and I) Hydrogen Bonds at the Organic/Inorganic Interface in Fluorinated Tetrathiafulvalenes Salts

Dautel¹,

Fourmigué²,

Canadell³

2001

Chem. Eur. J.

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The electrocrystallization of fluorinated bis(2,2'-difluoropropylenedithio)tetrathiafulvalene (1) in the presence of linear (ICl2-, IBr2-, I2Br-) or cluster ([Mo6Cl14]2-) anions affords 1:1 and 2:1 cation radical salts such as [1][ICl2] and [1]2[Mo6Cl14].(CH3CN)2. In both salts, the 1*+ radical ion adopts a boat conformation and envelops the anion through C-H...Hal(anion) (Hal(anion) = Cl, Br, I) hydrogen bonds. This demonstrates the activating role of the neighboring electron-withdrawing CF2 moieties in the stabilization of bi- or trimolecular neutral entities. With smaller linear anions, fluorine segregation controls the solid-state associations of the bimolecular [1]*+[X] entities, and gives rise to layered materials with a limited overlap interaction between the open-shell organic cations and magnetic spin chain behavior. With the larger [Mo6Cl14]2 ions, a strong overlap interaction between radical cations gives rise to diamagnetic [1]2(2+) dimers, which alternate with the cluster anions to form hybrid organic/inorganic ...[1]2(2+)[Mo6Cl14]2... chains. This behavior is also observed in [2]2(2+)[Mo6Cl14]2-.(CH2Cl2)2, in which compound 2 is the unsymmetrically substituted (ethylenedithio)(2,2'-difluoropropylenedithio)tetrathiafulvalene. On the other hand, the unsymmetrically substituted 2,2'-difluoropropylenedithiotetrathiafulvalene (3) affords a mixed-valence 4:1 salt with [Mo6Cl14]2, which is formulated as [3]4[Mo6Cl14].(CH3CN)2. This semiconducting salt is characterized by the coexistence of both the fluorine/fluorine segregation (with solvent inclusion) and the organic/inorganic segregation (with delocalized overlap interactions). Both Csp2-H...Cl and Csp3-H...Cl hydrogen bonds facilitate the stabilization of the organic/inorganic interface and the presence of conducting organic slabs.

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Chiral liquid-crystalline polyacrylates from (S)-(-)-2-methyl-1-butanol. Synthesis, mesomorphic properties and light scattering

Cited by 22 publications

References 7 publications

Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

Synthesis and mesomorphic properties of side chain liquid-crystalline biphenyl-phenyl polyacrylates

Activation of C−H⋅⋅⋅Halogen (Cl, Br, and I) Hydrogen Bonds at the Organic/Inorganic Interface in Fluorinated Tetrathiafulvalenes Salts

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