Phase Studies of Liquid Crystalline Side Chain Polymers Mixed with Low Molar Mass Liquid Crystals of Similar Structure

Finkelmann, Heino; Kock, H. J.; Rehage, G.

doi:10.1080/00268948208074466

Cited by 42 publications

(5 citation statements)

References 9 publications

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“…The growth of the spinodal process has been customarily analyzed in the context of a power law − by examining the change of wavenumber maximum ( q m ) and the corresponding peak intensity ( I m ) and where α and β are the growth exponents which have been predicted to be 1 / 3 and 1 for late stages of spinodal decomposition in binary systems. − …”

Section: Resultsmentioning

confidence: 99%

Phase Diagrams and Phase Separation Dynamics in Mixtures of Side-Chain Liquid Crystalline Polymers and Low Molar Mass Liquid Crystals

Chiu¹,

Zhou²,

Kyu³

et al. 1996

Macromolecules

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Miscibility phase diagrams and phase separation dynamics in mixtures of side-chain liquid crystalline polymers (SCLCP) and monomeric liquid crystals have been investigated experimentally in order to test with theoretical predictions. The theoretical calculation on equilibrium phase diagrams of binary nematic mixtures involves a combination of the Flory-Huggins (FH) free energy for isotropic mixing in conjunction with the Maier-Saupe (MS) free energy for nematic ordering of the mesogenic units. Two orientational order parameters and two nematic-isotropic (NI) transitions of the constituent mesogens are taken into consideration in the calculation. This combined FH-MS theory predicts a variety of phase diagrams depending on the relative strength of the cross-interaction between two dissimilar mesogens as compared to that in the same species. A series of epoxy resins [ethylene glycol glycidyl ether (EGDE)] grafted with mesogenic amines 4-(ω-aminoalkoxy)-4′-cyanobiphenyl were synthesized. The temperature-composition phase diagrams of these SCLCP mixtures and the eutectic low molar mass liquid crystal (E7) have been established by a cloud point method. The calculated phase diagrams are found to accord well with the experimental phase diagrams. The dynamics of phase separation has been investigated by means of time-resolved light scattering and optical microscopy. The time evolution of the structure factor following various temperature quenches into the nematic-liquid and/or nematicnematic coexistence regions has been analyzed in terms of a power law scheme.

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Section: Resultsmentioning

confidence: 99%

Phase Diagrams and Phase Separation Dynamics in Mixtures of Side-Chain Liquid Crystalline Polymers and Low Molar Mass Liquid Crystals

Chiu¹,

Zhou²,

Kyu³

et al. 1996

Macromolecules

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“…Nematic Free Energy and Order Parameter. The equilibrium phase behavior of mixtures of cross-linked polymers and nematic LC has been examined by various authors before. ,− ,, …”

Section: Cross-linked Polymers and Nematic Liquid Crystalsmentioning

confidence: 99%

“…Although simple, these models are found to be very useful for the interpretation of experimental phase diagrams obtained by optical microscopy, light scattering, and differential scanning calorimetry. , …”

Section: Introductionmentioning

confidence: 99%

Miscibility in Cross-Linked Polymer−Solvent Systems with Nematic Interactions

et al. 2000

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Model phase diagrams of cross-linked polymers and low molecular weight solvent systems with nematic interactions are discussed. A combination of classical theories of network elasticity due to cross-links, isotropic mixing with solvent, and a nematic interaction of the Maier-Saupe type yields a variety of phase behaviors. The network elasticity parameters and the Flory-Huggins interaction parameter are assumed to be function of the volume fraction in contrast to our previous studies of analogous systems. Effects of nematic order on the miscibility of cross-linked polymers and low molecular weight LC are discussed by comparison with the corresponding isotropic systems. The case of side chain liquid crystal cross-linked networks and isotropic solvents is also examined within the same theoretical scheme. The influence of cross-linking density and the reference polymer volume fraction at cross-linking on the phase behavior is also invoked.

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“…These mixtures have a biphasic region, and the addition of PBCB6 (having a higher T ni ) increased the temperatures T ni and T c ; see Figure a. The presence of a biphasic region is a common occurrence in solutions of polymers dissolved in small molecule nematic LCs. − Significantly, miscibility was observed over a wider temperature range in the nematic phase than the nematic temperature window of the host LC itself. In general, the addition of polymer increased the temperature range of the nematic phase (decreasing T g , Figure a, or T m , Figure b, and increasing T ni , Figure a).…”

Section: Resultsmentioning

confidence: 96%

Synthesis and Phase Behavior of Side-Group Liquid Crystalline Polymers in Nematic Solvents

et al. 2004

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A model system of side-group liquid crystalline polymers (SGLCPs) with systematically varied molecular weight (from 78 to 420 kg/mol; PDI ≤ 1.16) and spacer length (8−12 atoms long) was prepared by polymer analogous synthesis. Matching the structure of the mesogenic units to that of the nematic solvent produced excellent solubility, even at molecular weights an order of magnitude greater than in prior literature on SGLCP solutions. Addition of up to 10 wt % polymer did not affect the ordinary and extraordinary refractive indices of the nematic host (4-pentyl-4‘-cyanobiphenyl, 5CB), indicating that the order parameter was not significantly affected by the polymer.

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Phase Studies of Liquid Crystalline Side Chain Polymers Mixed with Low Molar Mass Liquid Crystals of Similar Structure

Cited by 42 publications

References 9 publications

Phase Diagrams and Phase Separation Dynamics in Mixtures of Side-Chain Liquid Crystalline Polymers and Low Molar Mass Liquid Crystals

Phase Diagrams and Phase Separation Dynamics in Mixtures of Side-Chain Liquid Crystalline Polymers and Low Molar Mass Liquid Crystals

Miscibility in Cross-Linked Polymer−Solvent Systems with Nematic Interactions

Synthesis and Phase Behavior of Side-Group Liquid Crystalline Polymers in Nematic Solvents

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