Flexible polymers in nematic solvents: Phase diagrams in dilute regime

Dubault, A.; Casagrande, C.; Veyssié, M.

doi:10.1080/01406568208084678

Cited by 36 publications

(21 citation statements)

References 3 publications

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“…Therefore, the model predicted that PS was completely segregated from nematic domains. For consistency purposes, the location of the hypothetical L þ L phase region was predicted using the FloryHuggins model, taking the polydispersity of PS into account as explained above, and using the interaction parameter given by equation (2). The predicted L þ L region was located inside the L þ N region indicating that two isotropic liquid phases cannot coexist at equilibrium for this particular system.…”

Section: Phase Diagrammentioning

confidence: 99%

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Polymer‐Dispersed Liquid Crystals Based on Polystyrene and EBBA: Analysis of Phase Diagrams and Morphologies Generated

Hoppe

Galante

Oyanguren

et al. 2003

Macro Chemistry & Physics

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As an example of thermoplastic/liquid crystal blends that do not exhibit a liquid‐liquid immiscibility region in their phase diagrams, a polystyrene (PS)/N‐4‐ethoxybenzylidene‐4′‐butylaniline (EBBA) blend was analyzed. The complete phase diagram was built up using thermal transitions determined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The boundary of the nematic + isotropic region was fitted with the Flory‐Huggins‐Maier‐Saupe model, extended to consider the polydispersity of PS. Main factors controlling the morphologies generated by thermal‐induced phase separation (TIPS) were the initial EBBA concentration in the blend and the cooling rate. Cooling at a fast rate led to small nematic domains with a narrow size distribution. Slow cooling rates led to the coexistence of very large and small dispersed domains. This was because of the large extent of coalescence of the droplets first generated associated with the continuation of the nucleation/growth process in a medium of increasing viscosity. The use of fast cooling rates might be important for the generation of a narrow size‐distribution of nematic droplets by TIPS in polymer‐dispersed liquid crystals (PDLC) used in electrooptical devices.Micrograph obtained by transmission optical microscopy without crossed polarizers, showing nematic domains dispersed in a glassy matrix arising by a fast cooling of the blend from 130 °C; composition of blend: 70 wt.‐% EBBA.magnified imageMicrograph obtained by transmission optical microscopy without crossed polarizers, showing nematic domains dispersed in a glassy matrix arising by a fast cooling of the blend from 130 °C; composition of blend: 70 wt.‐% EBBA.

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Section: Phase Diagrammentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Most of these blends exhibit a liquid-liquid (L-L) immiscibility region in their phase diagrams that precedes the formation of a nematic phase during the cooling step. Therefore, the generated morphologies are determined by the mechanism of the previous L-L phase separation.…”

Section: Introductionmentioning

confidence: 99%

Polymer‐Dispersed Liquid Crystals Based on Polystyrene and EBBA: Analysis of Phase Diagrams and Morphologies Generated

Hoppe

Galante

Oyanguren

et al. 2003

Macro Chemistry & Physics

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“…[3,4] Some mixtures containing liquid crystals also exhibit liquidliquid phase separations as seen in mixtures of normal fluids and polymer solutions. [5,6] In conjunction with experimental works to obtain temperature-composition diagrams, [3 -5] several molecular-thermodynamic models have also been proposed to calculate phase diagrams of mixtures containing liquid crystals. Reports on the first liquid crystalline polymers, [7] followed by the early patents describing the use of mesophases for producing solids with ultra-high orientation and properties, [8] stimulated hopes that methods to reproduce the complex molecular organization typical of biological assemblies had finally been discovered.…”

Section: Introductionmentioning

confidence: 99%

“…They have created a theoretical framework, which was particularly well suited for the description of a mixture containing a nematogen. [6,8,15] They combined an orientation-dependent energy with a partition function derived for a system of "hard" rod-like molecules in which the intermolecular Full Paper: We investigated mixed nematic liquid crystal/star-polymer systems and derived a new model based on Freed's lattice cluster theory to describe their phase behavior. To account for the highly oriented interactions between segments, the proposed model requires an additional parameter (de/k) related to the energy of the oriented interaction.…”

Section: Introductionmentioning

confidence: 99%

Phase Behavior of Nematic Liquid Crystal/Star-Polymer Systems

Yoon

Lee

Bae³

2002

Macromol. Chem. Phys.

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“…First, from a thermodynamic point of view, it has been established [17][18] [4,6,24] (Fig.1). [16] came to the conclusion that in crystalline isotactic vinyl polymers, the conformation of the polymer chains is helical, as shown in figure 2.…”

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confidence: 99%

Smectic E side-chain liquid crystalline poly(methacrylates)

et al. 1988

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Résumé. 2014 Une série homologue de trois poly(méthacrylates) liquides cristallins à groupes mésogènes latéraux a été étudiée par diffraction des rayons X. Les groupes mésogènes constitués par des groupes 4'-méthoxybiphénylyle étaient reliés au squelette macromoléculaire par des espaceurs souples de nature oligooxyéthyléniques. La structure smectique E monocouche de ces polymères a été analysée en termes de conformations du squelette macromoléculaire. Les groupes latéraux sont tous situés du même côté par rapport à la chaîne principale, et conduisent à des éléments de structure ayant la forme de rubans. Les rubans sont assemblés côte à côte avec les groupes mésogènes pointant alternativement vers le haut et vers le bas.Abstract. 2014 A homologous series of three side-chain liquid crystalline poly(methacrylates) with 4'-methoxybiphenylyl pendant mesogenic groups and oligo(ethylene-oxide) flexible spacers has been studied by X-ray diffraction. These polymers were shown to form a single layered smectic E structure, which has been analysed in terms of polymer chain conformation. The pendant groups were found to all hang on the same side of the polymer backbone to form ribbons, which are assembled side by side with an alternating up and down orientation of the pendant groups.

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Flexible polymers in nematic solvents: Phase diagrams in dilute regime

Cited by 36 publications

References 3 publications

Polymer‐Dispersed Liquid Crystals Based on Polystyrene and EBBA: Analysis of Phase Diagrams and Morphologies Generated

Polymer‐Dispersed Liquid Crystals Based on Polystyrene and EBBA: Analysis of Phase Diagrams and Morphologies Generated

Phase Behavior of Nematic Liquid Crystal/Star-Polymer Systems

Smectic E side-chain liquid crystalline poly(methacrylates)

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