Polymer as an important component of blends and composites with liquid crystals

Mucha, Maria

doi:10.1016/s0079-6700(02)00117-x

Cited by 286 publications

(180 citation statements)

References 240 publications

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“…Electric or magnetic field can transform the LC orientational structure, this changes the macroscopic optical properties of PDLC films. For example, when the ordinary refractive index (n) of LC with positive dielectric constant is close to the refractive index of polymer (np), the electric field applied perpendicular to the film plane switches the PDLC film from the scattering state into the transparent one [1][2][3][4][5]. At present, there have been well investigated PDLC films containing the nematic droplets with the most common configurations: bipolar for strong tangential anchoring, radial for strong homeotropic anchoring [6][7][8] and axial for strong homeotropic or weak anchoring [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Director configurations in nematic droplets with tilted surface anchoring

et al. 2016

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The polymer dispersed nematic liquid crystal with the tilted surface anchoring has been studied. The droplet orientational structures with two point surface defects-boojums and the surface ring defect are formed within the films. The director tilt angle  = 40  4 at the droplet interface and LC surface anchoring strength Ws ~ 10 -6 (J m -2 ) have been estimated. The bipolar axes within the studied droplets of oblate ellipsoidal form can be randomly oriented are oriented randomly relatively to the ellipsoid axes as opposed to the droplets with homeotropic and tangential anchoring.

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Section: Introductionmentioning

confidence: 99%

Director configurations in nematic droplets with tilted surface anchoring

et al. 2016

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“…PDLC materials are made of micrometer-size droplets of a small-molecule liquid crystal embedded in a polymer binder. The optical response of the droplets combined with the mechanical properties of the polymer make PDLC films a unique component in many electro-optical applications [2,5].…”

Section: Introductionmentioning

confidence: 99%

Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

Yue

Feng

et al. 2005

Journal of Colloid and Interface Science

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Nematic-isotropic interfaces exhibit novel dynamics due to anchoring of the liquid crystal molecules on the interface. The objective of this study is to demonstrate the consequences of such dynamics in the flow field created by an elongated nematic drop retracting in an isotropic matrix. This is accomplished by two-dimensional flow simulations using a diffuse-interface model. By exploring the coupling among bulk liquid crystal orientation, surface anchoring and the flow field, we show that the anchoring energy plays a fundamental role in the interfacial dynamics of nematic liquids. In particular, it gives rise to a dynamic interfacial tension that depends on the bulk orientation. Tangential gradient of the interfacial tension drives a Marangoni flow near the nematic-isotropic interface. Besides, the anchoring energy produces an additional normal force on the interface that, together with the interfacial tension, determines the movement of the interface. Consequently, a nematic drop with planar anchoring retracts more slowly than a Newtonian drop, while one with homeotropic anchoring retracts faster than a Newtonian drop. The numerical results are consistent with prior theories for interfacial rheology and experimental observations.  2005 Elsevier Inc. All rights reserved.

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“…When a PDLC film is made with an LC having an extraordinary refractive index (ne) different from the refractive index (np) of the polymer matrix, this refractive index mismatch condition and the randomly distributed optical axes of the droplets leave the PDLC film opaque in its field-off state [5][6][7]. However, when the ordinary refractive index (no) of the LC is equal to np, the initially opaque PDLC layer can be made transparent by applying a voltage to reorient the LCs in the polymer matrix and ensure that the refractive indexes match for normally incident light [5][6][7]. Unlike other LC-based devices, PDLCbased devices are easily implemented as LC alignment layers and polarizers are not required.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Adhesion and Transmittance Uniformity in Laminated Polymer-Dispersed Liquid Crystal Films

Yoo¹,

Park²,

Park³

2014

Journal of the Optical Society of Korea

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We propose a two-step UV irradiation procedure to fabricate polymer-dispersed liquid crystal (PDLC) films by lamination. During the first UV treatment, before lamination, the UV-curable monomers coated on one film substrate are solidified through photo-polymerization as the phase separation between the liquid crystals and the monomers. Introducing an adhesion-enhancement layer on the other plastic substrate and controlling the UV irradiation conditions ensure that UV-induced cross-linkable functional groups remain on the surfaces of the photo-polymerized layers. Thereby, the adhesion stability between the top and bottom films is much improved during a second (post-lamination) UV treatment by further UV-induced cross-linking at the interface. Because the adhesion-enhancement and PDLC layers prepared by the bar-coating process are solidified before lamination, the PDLC droplet distribution and the cell gap between the two plastic substrates remain uniform under the lamination pressure. This ensures that the voltage-controlled light transmittance is uniform across the entire sample.

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Polymer as an important component of blends and composites with liquid crystals

Cited by 286 publications

References 240 publications

Director configurations in nematic droplets with tilted surface anchoring

Director configurations in nematic droplets with tilted surface anchoring

Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

Enhanced Adhesion and Transmittance Uniformity in Laminated Polymer-Dispersed Liquid Crystal Films

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