Novel easy to fabricate liquid crystal composite with potential for electrically or thermally controlled transparency windows

Abdulhalim, Ibrahim; Madhuri, P. Lakshmi; Diab, Mahmud; Mokari, Taleb

doi:10.1364/oe.27.017387

Cited by 28 publications

(18 citation statements)

References 62 publications

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“…The experimental set‐up is described in our earlier paper. [ 41 ] The measurements were carried out without using any polarizers. As the applied voltage increases, the profiles show a monotonic decrease in the scattering over the entire wavelength range.…”

Section: Resultsmentioning

confidence: 99%

“…The motivation for the work is stimulated from the fact that LC molecules can infiltrate nano and micro pores; thus when mixed with cochleates, a new tunable photonic metamaterial can be formed. A recent study, [ 40 ] have shown this using nanoporous Si micro‐particles mixed with nematic LC, and another study [ 41 ] have shown the same when an aggregate of octadecanol is mixed with liquid crystal. The main concept of this group of devices is based on the fact that as the LC molecules penetrate the porous particles, the average refractive index (RI) of the composite particle becomes close to one of the principal indices of the LC; in most cases, the lowest RI n ⊥ is close to the index of the isotropic state

n_{iso} = \sqrt{(2 n_{⊥}^{2} + n_{| |}^{2}) / 3} \approx n_{⊥}

.…”

Section: Introductionmentioning

confidence: 91%

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Cochleate‐Doped Liquid Crystal as Switchable Metamaterial Window Mediated by Molecular Orientation Modified Aggregation

Madhuri

Shuddhodana

Judeh

et al. 2020

Part & Part Syst Charact

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A diversity of fascinating hollow and porous micro and nanoparticles are being developed for drug delivery purposes; however, their applications in other systems are barely touched. When filled by an active material, they form a tunable photonic metamaterial. Here, a small concentration of organic hollow cylinders called cochleates embedded into liquid crystals (LCs) is demonstrated to form a new switchable composite to control light scattering with voltage and temperature. The biocompatible cochleates, which are hollow, tube‐like, and hydrophilic in nature, can trap the liquid crystal molecules thus altering the system behavior. A switching device as thin as 6 µm with 12 wt% cochleates concentration is shown to be adequate to reveal a switchable privacy window. Possible molecular arrangement of the liquid crystal within the cochleate particles is suggested, and unexpected increase of the scattering with temperature depending on the applied voltage is observed as a result of change in the cochleate aggregation depending on the LC molecule orientation.

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Section: Resultsmentioning

confidence: 99%

n_{iso} = \sqrt{(2 n_{⊥}^{2} + n_{| |}^{2}) / 3} \approx n_{⊥}

.…”

Section: Introductionmentioning

confidence: 91%

Cochleate‐Doped Liquid Crystal as Switchable Metamaterial Window Mediated by Molecular Orientation Modified Aggregation

Madhuri

Shuddhodana

Judeh

et al. 2020

Part & Part Syst Charact

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“…Tremendous efforts were progressed previously on optimization of PDLC materials and structure of devices to fabricate low voltage PDLCs with enhanced electro-optical properties and were sufficiently impressive [20,21,[36][37][38][39][40][41]. Despite promising results, attempts at constructing low-voltage driven PDLCs have involved either cumbersome fabrication procedures or compromised on other salient features of PDLCs [36][37][38][39][40][41][42][43][44][45][46][47][48]. There is therefore high interest in developing an efficient method to reduce the driving voltage of PDLCs without sacrificing other desirable features.…”

Section: Introductionmentioning

confidence: 99%

High-Performance Polymer Dispersed Liquid Crystal Enabled by Uniquely Designed Acrylate Monomer

et al. 2020

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The widespread electro–optical applications of polymer dispersed liquid crystals (PDLCs) are hampered by their high-driving voltage. Attempts to fabricate PDLC devices with low driving voltage sacrifice other desirable features of PDLCs. There is thus a clear need to develop a method to reduce the driving voltage without diminishing other revolutionary features of PDLCs. Herein, we report a low-voltage driven PDLC system achieved through an elegantly simple and uniquely designed acrylate monomer (A3DA) featuring a benzene moiety with a dodecyl terminal chain. The PDLC films were fabricated by the photopolymerization of mono- and di-functional acrylate monomers (19.2 wt%) mixed in a nematic liquid crystal E7 (80 wt%). The PDLC film with A3DA exhibited an abrupt decline of driving voltage by 75% (0.55 V/μm) with a high contrast ratio (16.82) while maintaining other electro–optical properties almost the same as the reference cell. The response time was adjusted to satisfactory by tuning the monomer concentration while maintaining the voltage significantly low (3 ms for a voltage of 0.98 V/μm). Confocal laser scanning microscopy confirmed the polyhedral foam texture morphology with an average mesh size of approximately 2.6 μm, which is less in comparison with the mesh size of reference PDLC (3.4 μm), yet the A3DA-PDLC showed low switching voltage. Thus, the promoted electro–optical properties are believed to be originated from the unique polymer networks formed by A3DA and its weak anchoring behavior on LCs. The present system with such a huge reduction in driving voltage and enhanced electro–optical performance opens up an excellent way for abundant perspective applications of PDLCs.

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“…It is worth mentioning that the effect of dynamic light scattering in liquid crystals was not totally abandoned. Recently, it found very promising applications in the development of dynamic shutters and smart windows [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals

Garbovskiy

2020

Nanomaterials

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Nanomaterials in liquid crystals are a hot topic of contemporary liquid crystal research. An understanding of the possible effects of nanodopants on the properties of liquid crystals is critical for the development of novel mesogenic materials with improved functionalities. This paper focuses on the electrical behavior of contaminated nanoparticles in liquid crystals. More specifically, an analogy between electrolytes and ion-generating nanomaterials in liquid crystals is established. The physical consequences of this analogy are analyzed. Under comparable conditions, the number of ions generated by nanomaterials in liquid crystals can be substantially greater than the number of ions generated by electrolytes of similar concentration.

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Novel easy to fabricate liquid crystal composite with potential for electrically or thermally controlled transparency windows

Cited by 28 publications

References 62 publications

Cochleate‐Doped Liquid Crystal as Switchable Metamaterial Window Mediated by Molecular Orientation Modified Aggregation

Cochleate‐Doped Liquid Crystal as Switchable Metamaterial Window Mediated by Molecular Orientation Modified Aggregation

High-Performance Polymer Dispersed Liquid Crystal Enabled by Uniquely Designed Acrylate Monomer

On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals

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