The Interfacial Free Energy of Nematogen Droplets in an Isotropic Matrix: Determination of its Temperature Dependence from Coalescence Kinetics

Smith, George W.; Vaz, Nuno A.; Vansteenkiste, T. H.

doi:10.1080/00268948908042694

Cited by 8 publications

(4 citation statements)

References 19 publications

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“…This large reduction in the case of thiol−enes might be due to two separate effects, including a change in the inherent morphology and chemical differences at the interface that reduce the anchoring strength. The more elastic nature of the thiol−ene polymer would discourage strong interactions and anchoring of the droplets at the polymer interface . A much smoother interface also reduces the surface/volume ratio for domains of equal average diameter.…”

Section: Resultsmentioning

confidence: 99%

Switchable Holographic Polymer-Dispersed Liquid Crystal Reflection Gratings Based on Thiol−Ene Photopolymerization

et al. 2003

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Holographic reflection gratings in polymer-dispersed liquid crystals (H-PDLCs) were formed by thiol−ene photopolymerization. Using UV laser light and a single prism, electrically switchable reflection gratings in blue, green, yellow, and red colors were fabricated. Results indicate that thiol−ene polymers function as better hosts for H-PDLC than multifunctional acrylate as matrixes. These differences are the result of a much different temporal structure development caused by fundamental differences in the polymerization propagation mechanism: a step-growth addition mechanism for the thiol−ene system compared to a chain-growth addition mechanism in multifunctional acrylates. Morphology studies by TEM support these conclusions, as striking differences in droplet shape and uniformity are observed. Discrete nematic droplets with a nearly spherical shape were seen. Thiol−ene polymers offer lower switching fields, higher diffraction efficiencies, better optical properties, and higher thermal stabilities. The response times of the thiol−ene gratings were five times slower than those of acrylates.

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Section: Resultsmentioning

confidence: 99%

Switchable Holographic Polymer-Dispersed Liquid Crystal Reflection Gratings Based on Thiol−Ene Photopolymerization

et al. 2003

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“…(26)) the relaxation rate is enhanced by the polymer as a consequence of the enhancement of the surface tension due to concentration variation Eq. (39) (see also the experimental results [17].…”

Section: General Dispersion Relationmentioning

confidence: 83%

“…(39) with the experimental value γ c = 0.1erg/cm 2 [17] we find K c = 5.5 · 10 −4 dyn and l c = 6.6 · 10 −5 cm. To obtain the CH dispersion relation [18,19] (valid in the inner-outer region) we conveniently rewrite Eq.…”

Section: Inner Regionmentioning

confidence: 87%

Waves at the Nematic-Isotropic Interface

Popa-Nita

Oswald

Sluckin

2005

Molecular Crystals and Liquid Crystals

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We examine surface modes at the nematic-isotropic interface in polymer-liquid-crystal mixtures using the dynamical Landau-de Gennes model for the orientational (non-conserved) order parameter coupled with Cahn-Hilliard equation for concentration (conserved order parameter) and with hydrodynamic degrees of freedom. The generalized dispersion relation is obtained and analyzed in particular cases. Orientational order parameter relaxation dominates in the short wavelength limit, while in the long wavelength limit viscous damping becomes important. The effect of polymer is to increase the surface tension and as a consequence the relaxation rate in the hydrodynamic limit. Finally, we discuss how to measure experimentally the dispersion relation.

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“…Some authors theoretically studied the interfacial tension of mixtures of a polymer and a liquid crystal based on the lattice Monte Carlo simulation [4] and the Helfand lattice theory [5]. Smith et al measured the interfacial tension of a nematic liquid crystal (5CB) immersed in polydimethylsiloxane (PDMS) matrix and showed that the interfacial free energy is decreased as the temperature is increased [6].…”

Section: Introductionmentioning

confidence: 99%