Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Hwang, Byoung Har; Ahn, Hyung Jin; Rho, Soon Joon; Chae, Soo Sang; Baik, Hong Koo

doi:10.1021/la9005339

Cited by 32 publications

(15 citation statements)

References 36 publications

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“…The van der Waals force, prevalent in non‐covalent interaction between molecules, is fundamental to constructing assembly structures. In general, the van der Waals force could be further divided into three types: Keesom forces (orientation force), Debye forces (induction force), and London dispersion forces . The Keesom force, appearing between two permanent dipoles, is an attractive dipole‐dipole interaction over various rotational orientations of dipoles.…”

Section: Van Der Waals Interactionsmentioning

confidence: 99%

Interparticle Forces Underlying Nanoparticle Self‐Assemblies

Luo

Wang

2015

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Studies on the self-assembly of nanoparticles have been a hot topic in nanotechnology for decades and still remain relevant for the present and future due to their tunable collective properties as well as their remarkable applications to a wide range of fields. The novel properties of nanoparticle assemblies arise from their internal interactions and assemblies with the desired architecture key to constructing novel nanodevices. Therefore, a comprehensive understanding of the interparticle forces of nanoparticle self-assemblies is a pre-requisite to the design and control of the assembly processes, so as to fabricate the ideal nanomaterial and nanoproducts. Here, different categories of interparticle forces are classified and discussed according to their origins, behaviors and functions during the assembly processes, and the induced collective properties of the corresponding nanoparticle assemblies. Common interparticle forces, such as van der Waals forces, electrostatic interactions, electromagnetic dipole-dipole interactions, hydrogen bonds, solvophonic interactions, and depletion interactions are discussed in detail. In addition, new categories of assembly principles are summarized and introduced. These are termed template-mediated interactions and shape-complementary interactions. A deep understanding of the interactions inside self-assembled nanoparticles, and a broader perspective for the future synthesis and fabrication of these promising nanomaterials is provided.

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Section: Van Der Waals Interactionsmentioning

confidence: 99%

Interparticle Forces Underlying Nanoparticle Self‐Assemblies

Luo

Wang

2015

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135

123

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“…B. H. Hwang et al . reported the successful alignment of LCs with negative dielectric anisotropy on a-SiO x thin film deposited over indium tin oxide (ITO) 17 . In an another example, P. S. Noonan et al .…”

Section: Introductionmentioning

confidence: 99%

Vertical Alignment of Liquid Crystals Over a Functionalized Flexible Substrate

Sivaranjini

Mangaiyarkarasi

Ganesh

et al. 2018

Sci Rep

163

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A simple and effective approach for vertical alignment of liquid crystals (LCs) over a functionalized transparent flexible substrate is described. Surface characterization of this commercially available plastic substrate through X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared spectroscopy (ATR-IR) indicated that cellulose acetate is main component of the transparent substrate. This substrate was chemically functionalized with a suitable LC compound. A trimethoxysilane terminated new rod-shaped mesogen is synthesized and covalently attached to the pre-treated film through silane condensation reaction. LC functionalization of the polymer film is confirmed through contact angle (CA), atomic force microscopy (AFM), XPS and ATR-IR spectroscopy studies. Versatility of the LC modified flexible substrates for the alignment of bulk LC sample at substrate-LC interface was assessed for nematic (N) and smectic A (SmA) phases. Remarkably, LC functionalized cellulose acetate films were found to be highly efficient in assisting a perfect homeotropic alignment of LCs (for both, a room temperature N and a high temperature SmA phase) over the entire area of the LC sample under observation indicating their superior aligning ability in comparison to their unmodified and octadecyltrimethoxysilane (OTS) modified counterparts. The demonstrated method of surface modification of flexible polymer film is easy, surface modified substrates are stable for several months, retained their aligning ability intact and more importantly they are reusable with maximum delivery.

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“…After irradiation by LPUV light, the absorption of light with polarization direction parallel to the polarization direction of the activating light decreases (curve 1), while that for an orthogonal polarization direction increases (curve 2). The evolution of the polarized absorption spectra after UV illumination does not reveal any noticeable contribution of photochemical reactions, as the average absorption

D_{ave} = (D_{| |} + 2 D_{⊥}) / 3

remains the same for any fixed value of the exposure time. The latter also means that we cannot detect by our spectral measurements the process of cis–trans isomerization, as usually the cis ‐ and trans ‐forms exist simultaneously, resulting in a corresponding variation of the average spectral absorption D ave …”

Section: Resultsmentioning

confidence: 97%

Nanoscale engineering of photo aligning Cibacron Brilliant Yellow

et al. 2013

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Photoalignment properties on commercially available textile dye Cibacron Brilliant Yellow exhibit excellent alignment quality. Thin layer of solid films (about 20–100 nm in thickness) shows high thermal and photo stability. Excellent surface energy values (both azimuthal and polar) were achieved. The distinguished alignment properties of this dye extend the field of the sulfuric azo dyes effective for photoalignment. An attractive feature of this dye is its low curing temperature, which is essential for plastic substrates to use it as flexible devices.

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Vertical Alignment of Liquid Crystals with Negative Dielectric Anisotropy on an Inorganic Thin Film with a Hydrophilic Surface

Cited by 32 publications

References 36 publications

Interparticle Forces Underlying Nanoparticle Self‐Assemblies

Interparticle Forces Underlying Nanoparticle Self‐Assemblies

Vertical Alignment of Liquid Crystals Over a Functionalized Flexible Substrate

Nanoscale engineering of photo aligning Cibacron Brilliant Yellow

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