scholarly journals Textures of Nematic Liquid Crystal Cylindric-Section Droplets Confined by Chemically Patterned Surfaces

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 65
Author(s):  
Peng Bao ◽  
Daniel A. Paterson ◽  
Sally A. Peyman ◽  
J. Cliff Jones ◽  
Jonathan A. T. Sandoe ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Surface Energy ◽  
High Surface ◽  
Longitudinal Section ◽  
Patterned Surfaces ◽  
Director Field ◽  
Low Surface Energy ◽  
Air Interface ◽  
High Surface Energy

The director fields adopted by nematic liquid crystals (LCs) that are confined by the surface to form long, thin droplets are investigated using polarising optical microscopy. Samples are produced by de-wetting of the LC on a surface patterned with alternating high-surface energy and low-surface energy stripes of 10–30 μm width. The droplets obtained are expected to adopt a profile which is that of a longitudinal section of a cylinder and, as this suggests, the director fields observed are variants in the case where the LC is constrained in a cylindrical capillary or fibre. Hence, when there is normal anchoring at the air interface, the textures observed are related to the well-known escaped radial texture (for the nematic LC mixture E7) or plane polar texture (for the LC mixture MLC6609). More surprising is the observation that the nematic LC mixture MLC7023, which is anchored in a planar or tilted manner at the air interface, also gives what appears to be an escaped radial director field. As an exploration of the possibility of using these systems in creating sensors, the effects of adding a chiral dopant and of adding water to the substrates are also investigated.

scholarly journals Programming emergent symmetries with saddle-splay elasticity

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yu Xia ◽  
Andrew A. DeBenedictis ◽  
Dae Seok Kim ◽  
Shenglan Chen ◽  
Se-Um Kim ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Elastic Constant ◽  
Optoelectronic Devices ◽  
Surface States ◽  
Patterned Surfaces ◽  
Director Field ◽  
Surface Anchoring ◽  
Fast Switching ◽  
Low Field

Abstract The director field adopted by a confined liquid crystal is controlled by a balance between the externally imposed interactions and the liquid’s internal orientational elasticity. While the latter is usually considered to resist all deformations, liquid crystals actually have an intrinsic propensity to adopt saddle-splay arrangements, characterised by the elastic constant $${K}_{24}$$ K 24 . In most realisations, dominant surface anchoring treatments suppress such deformations, rendering $${K}_{24}$$ K 24 immeasurable. Here we identify regimes where more subtle, patterned surfaces enable saddle-splay effects to be both observed and exploited. Utilising theory and continuum calculations, we determine experimental regimes where generic, achiral liquid crystals exhibit spontaneously broken surface symmetries. These provide a new route to measuring $${K}_{24}$$ K 24 . We further demonstrate a multistable device in which weak, but directional, fields switch between saddle-splay-motivated, spontaneously-polar surface states. Generalising beyond simple confinement, our highly scalable approach offers exciting opportunities for low-field, fast-switching optoelectronic devices which go beyond current technologies.

Bio-mimicking hybrid polymer architectures as adhesion promoters for low and high surface energy substrates

2021 ◽  
Author(s):  
Monisha Baby ◽  
Vijayalakshmi K. Periya ◽  
Bhuvaneshwari Soundiraraju ◽  
Nisha Balachandran ◽  
Suchithra Cheriyan ◽  
...  
Keyword(s):  
Surface Energy ◽  
High Surface ◽  
Hybrid Polymer ◽  
Energy Substrates ◽  
Adhesion Promoters ◽  
Polymer Architectures ◽  
High Surface Energy

Passivation of High-Surface-Energy Sites of Milled Ibuprofen Crystals via Dry Coating for Reduced Cohesion and Improved Flowability

2013 ◽  
Vol 102 (7) ◽  
pp. 2282-2296 ◽  
Author(s):  
Xi Han ◽  
Laila Jallo ◽  
Daniel To ◽  
Chinmay Ghoroi ◽  
Rajesh Davé
Keyword(s):  
Surface Energy ◽  
High Surface ◽  
Dry Coating ◽  
High Surface Energy

scholarly journals A Highly Active Oxygen Evolution Catalyst for Lithium-Oxygen Batteries Enabled by High-Surface-Energy Facets

Joule ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 1511-1521 ◽  
Author(s):  
Nien-Chu Lai ◽  
Guangtao Cong ◽  
Zhuojian Liang ◽  
Yi-Chun Lu
Keyword(s):  
Surface Energy ◽  
Oxygen Evolution ◽  
High Surface ◽  
Active Oxygen ◽  
Highly Active ◽  
High Surface Energy ◽  
Lithium Oxygen Batteries

Electrochemical supermolecular templating of mesoporous Rh films

Nanoscale ◽  
2019 ◽  
Vol 11 (22) ◽  
pp. 10581-10588 ◽  
Author(s):  
Kenya Kani ◽  
Jeonghun Kim ◽  
Bo Jiang ◽  
Md. Shahriar A. Hossain ◽  
Yoshio Bando ◽  
...  
Keyword(s):  
Surface Energy ◽  
High Surface ◽  
Soft Templating ◽  
High Surface Energy

Making mesoporous rhodium (Rh) with traditional soft-templating methods is challenging because Rh has a high surface energy compared to other metals.

scholarly journals Magnetic Properties, Adhesion, and Nanomechanical Property of Co40Fe40W20 Films on Si (100) Substrate

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Wen-Jen Liu ◽  
Yung-Huang Chang ◽  
Sin-Liang Ou ◽  
Yuan-Tsung Chen ◽  
You-Cheng Liang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Surface Energy ◽  
Resonance Frequency ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
High Surface ◽  
Contact Angles ◽  
Thickness Effect ◽  
High Coercivity ◽  
High Surface Energy

In this study, a Co40Fe40W20 alloy was sputtered onto Si (100) with thicknesses (tf) ranging from 18 to 90 nm, and the corresponding structure, magnetic properties, adhesive characteristics, and nanomechanical properties were investigated. X-ray diffraction (XRD) patterns of the Co40Fe40W20 films demonstrated a significant crystalline body-centered cubic (BCC) CoFe (110) structure when the thickness was 42 nm, and an amorphous status was shown when the thickness was 18 nm, 30 nm, 60 nm, and 90 nm. The saturation magnetization (Ms) showed a saturated trend as tf was increased. Moreover, the coercivity (Hc) showed a minimum 1.65 Oe with 30 nm. Hc was smaller than 4.5 Oe owing to the small grain size distribution and amorphous structure, indicating that the Co40Fe40W20 film had soft magnetism. The low-frequency alternating current magnetic susceptibility (χac) decreased as the frequency was increased. The χac revealed a thickness effect when greater thicknesses had a large χac. The maximum χac and optimal resonance frequency (fres) of Co40Fe40W20 were investigated. The maximum χac indicated the spin sensitivity and was maximized at the optimal resonance frequency. The 90 mm thickness had the highest χac 0.18 value at an fres of 50 Hz. The contact angles of the Co40Fe40W20 films are less than 90°, which indicated that the film had a good wetting effect and hydrophilicity. The surface energy was correlated with the adhesion and displayed a concave-down trend. CoFeW films can be used as a seed or buffer layer; therefore, the surface energy and adhesion are very important. The highest surface energy was 30.12 mJ/mm2 at 42 nm and demonstrated high adhesion. High surface energy has corresponding strong adhesive performance. The increased surface roughness can induce domain wall pinning effect and high surface energy, causing a high coercivity and strong adhesion. The increase of hardness and Young’s modulus could be reasonably inferred from the thinner CoFeW films. The hardness and Young’s modulus of CoFeW films are also displayed to saturated tendency when increasing thickness.

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