Analysis of dichroic dye-doped polymer-dispersed liquid crystal materials for display devices

Kumar, Pankaj; Neeraj,; Kang, Shin‐Woong; Lee, Seung Hee; Raina, K. K.

doi:10.1016/j.tsf.2011.06.038

Cited by 44 publications

(17 citation statements)

References 33 publications

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“…A variation in adhesion work enforces transformations of one type of nematic director arrangement into another, leading to variability of LC droplet configurations. Recent studies have shown that the morphology of LC domains inside the polymer matrix plays an important role in determining the electro‐optical switching of dye‐doped PDLC systems . To examine the effect of surface anchoring conditions, we investigated the morphologies of phase separated dye‐doped LC droplets embedded in polymer matrix and the results are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

A method for estimating interfacial tension of liquid crystal embedded in polymer matrix forming PDLC

Deshmukh

Malik

2014

J of Applied Polymer Sci

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A simple and convenient method based on sessile drop technique for measuring surface tensions of polymer and nematic liquid crystal (LC) is described. Contact angles formed by drops of probe liquids and a nematic LC on a photocurable polymer were measured. The surface energies were evaluated using the Fowkes method, Neumann's equation, and new equations developed based on Neumann's approach. The values of surface tensions were used to evaluate the interfacial interaction in term of work of adhesion between the LC and polymer. Further, the effect of dichroic dye on the extent of interaction and work of adhesion was examined by measuring contact angle in consequence of dye addition. A difference in work of adhesion between the lower and higher dye‐doped LC droplets gave an indication of affinity relationship between polymer and LC molecules. A change in work of adhesion resulted in variability of nematic director configurations inside phase separated LC droplets embedded in polymer matrix; when viewed under polarizing optical microscope. Thus, our approach of estimating surface energy of polymer and LC has found to be useful in determining interaction at polymer–LC interface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41137.

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Section: Resultsmentioning

confidence: 99%

A method for estimating interfacial tension of liquid crystal embedded in polymer matrix forming PDLC

Deshmukh

Malik

2014

J of Applied Polymer Sci

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“…In our recent reported work, the dopants such as carbon nanotube, azo and anthra dyes are employed to enhance the EO properties of normal mode PDLCs . These dyes have good optical and alignment properties as well as high solubility in LC hosts, which resulted in LC devices of higher CRs with reduced applied fields.…”

Section: Introductionmentioning

confidence: 99%

Preparation and electrooptic study of reverse mode polymer dispersed liquid crystal: Performance augmentation with the doping of nanoparticles and dichroic dye

Sharma

Kumar

Chinky

et al. 2019

J of Applied Polymer Sci

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Reported herein, the preparation, morphological, and electrooptic (EO) characterization of reverse mode polymer dispersed liquid crystals (PDLCs) with nematic liquid crystal (LC) and UV curable polymer optical adhesive using polymerization induced phase separation method. The PDLCs are switchable between transparent and opaque states due to the homeotropic and planar alignment of LC in their OFF and ON states of applied voltage, respectively. Further, effect of doping of a fixed concentration of azo dye and silica nanoparticles (NPs) on morphological, EO and response characteristics of same PDLC sample was also analyzed. Experimental results showed that doped reverse mode PDLCs have the higher OFF state optical transmission and boost up in the scattering ON state compared with pristine reverse mode PDLC. The phenomenon is also supported by extinction coefficient and absorption study based on Beer's law. The threshold and operating voltages were found reduced ~1.56 and ~1.73 times for NPs and (NPs + dye) doped reverse mode PDLCs, respectively, along with better contrasts to the pristine reverse mode PDLC. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48745.

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“…A variety of works are found in the literature in which azobenzene moieties are added in PDLC‐type device formulations, in most cases in order to improve their properties and performance (e.g., optical transmission, contrast ratio, switching behavior, and absorbance factor) . However, a great effort has been made on this field to obtain photoresponsive or optically controllable composite films, attractive for specific applications in photonics and optoelectronics (e.g., optical sensors, optical shutters, diffractive optical elements, filters, and spatial light modulators).…”

Section: Introductionmentioning

confidence: 99%

Reaction‐Induced Phase Separation: A Strategy to Synthesize Azobenzene‐Modified All‐Optical PDLC Devices

Orofino

Oyanguren

Galante

2018

Macro Chemistry & Physics

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This work presents the synthesis of all‐optical polymer dispersed liquid crystals (PDLC) devices, in which the reversible trans–cis photoisomerization of azobenzene groups is used to induce the transition in the liquid crystal (LC) phase, activating the film from an opaque to a translucent state. The appropriate morphology is obtained through a reaction‐induced phase separation strategy using an epoxy–amine matrix modified with azobenzene precursors and the addition of a thermoplastic polymer (polystyrene, PS), which promotes the phase separation and the preferential location of the LC in separated domains. Formulations with liquid crystal content of 50 wt%, 5 wt% of modifier (PS), and 10 wt% of azo‐precursor present a reversible on–off optical response when irradiating the sample with the activation beam at λ = 488 nm. It is demonstrated that the liquid crystal responds according to the expected cooperative movement of orientation with the azobenzene groups. Based on the study of the PDLC devices obtained, its potential technological application can be confirmed.

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Analysis of dichroic dye-doped polymer-dispersed liquid crystal materials for display devices

Cited by 44 publications

References 33 publications

A method for estimating interfacial tension of liquid crystal embedded in polymer matrix forming PDLC

A method for estimating interfacial tension of liquid crystal embedded in polymer matrix forming PDLC

Preparation and electrooptic study of reverse mode polymer dispersed liquid crystal: Performance augmentation with the doping of nanoparticles and dichroic dye

Reaction‐Induced Phase Separation: A Strategy to Synthesize Azobenzene‐Modified All‐Optical PDLC Devices

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