Alignment of liquid crystals using Langmuir‒Blodgett films of unsymmetrical bent-core liquid crystals

Choudhary, Keerti; Gupta, R. K.; Pratibha, R.; Sadashiva, B. K.; Manjuladevi, V.

doi:10.1080/02678292.2019.1574035

Cited by 10 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This technique, already used to deposit rod-like materials of different natures like cellulose nanocrystals [ 21 ] or carbon nanotubes [ 22 ], represents a valuable tool to determine the surface alignment of BCMs and to study their anchoring properties. The resulting films are of interest by themselves, e.g., in the case of ferroelectric LCs, or they can be used as aligning substrates for bulk LCs [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”

Section: Introductionmentioning

confidence: 99%

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Vita,

Adamo,

Campana

et al. 2024

Nanomaterials

View full text Add to dashboard Cite

Bent-core liquid crystals, a class of mesogenic compounds with non-linear molecular structures, are well known for their unconventional mesophases, characterized by complex molecular (and supramolecular) ordering and often featuring biaxial and polar properties. In the nematic phase, their unique behavior is manifested in the formation of nano-sized biaxial clusters of layered molecules (cybotactic groups). While this prompted their consideration in the quest for nematic biaxiality, experimental evidence indicates that the cybotactic order is only short-ranged and that the nematic phase is macroscopically uniaxial. By combining atomic force microscopy, neutron reflectivity and wide-angle grazing-incidence X-ray scattering, here, we demonstrate that multilayer films of a bent-core nematic, deposited on silicon by a combined Langmuir–Blodgett and Langmuir–Schaefer approach, exhibit macroscopic in-plane ordering, with the long molecular axis tilted with respect to the sample surface and the short molecular axis (i.e., the apex bisector) aligned along the film compression direction. We thus propose the use of Langmuir films as an effective way to study and control the complex anchoring properties of bent-core liquid crystals.

show abstract

Section: Introductionmentioning

confidence: 99%

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Vita,

Adamo,

Campana

et al. 2024

Nanomaterials

View full text Add to dashboard Cite

show abstract

“…There are several forms of shape anisotropic LC molecules which can form a stable Langmuir monolayer at the air-water interface and show a variety of interesting phenomena. There are several studies on Langmuir monolayer and LB films of rod shaped [26], disc-shaped [27], and bow-shaped [25,28] liquid crystal molecules. There are some studies on non-traditional LC molecules [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Photoinduced modulation of refractive index in Langmuir-Blodgett films of azo-based H-shaped liquid crystal molecules

Joshi

Gayakwad²,

Manjuladevi³

et al. 2022

Journal of Molecular Liquids

Self Cite

View full text Add to dashboard Cite

“…In this context, the deposition of the Langmuir films of BCMs on proper substrates can provide both an ideal system for the study of LC anchoring on the molecular scale and a suitable approach to obtain aligning surfaces with controlled anchoring conditions [21][22][23][24][25][26][27][28][29][30][31][32][33]. A Langmuir monolayer is formed at the air-water interface by dispersing insoluble molecules over water; compression of the film by moving mechanical barriers determines the molecular arrangement in the monolayer, which can then be transferred onto a solid substrate.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, obtaining an upright orientation of the molecules over water, and then over a solid substrate, is much easier if one of the tails is modified by the insertion of a hydrophilic end group. This approach has been discussed in several papers, and the structural features of the resulting films are generally well understood [22,[28][29][30]33]. Additionally, the possibility of obtaining stable thin films from conventional BCMs with hydrophobic aliphatic tails has been reported in the literature, with tentative structural models deduced from qualitative considerations of the molecular hydrophobic/hydrophilic properties, and from geometrical arguments about the area per molecule in the isotherm.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Structure of Langmuir–Blodgett Film of Bent-Core Molecules

et al. 2022

View full text Add to dashboard Cite

Bent-core mesogens (BCMs) are a class of thermotropic liquid crystals featuring several unconventional properties. However, the interpretation and technological exploitation of their unique behavior have been hampered by the difficulty of controlling their anchoring at surfaces. To tackle this issue, we report the nanoscale structural characterization of BCM films prepared using the Langmuir–Blodgett technique. Even though BCMs are quite different from typical amphiphilic molecules, we demonstrate that stable molecular films form over water, which can then be transferred onto silicon substrates. The combination of Brewster angle microscopy, atomic force microscopy, and X-ray reflectivity measurements shows that the molecules, once transferred onto a solid substrate, form a bilayer structure with a bottom layer of flat molecules and an upper layer of upright molecules. These results suggest that Langmuir–Blodgett films of BCMs can provide a useful means to control the alignment of this class of liquid crystals.

show abstract

Alignment of liquid crystals using Langmuir‒Blodgett films of unsymmetrical bent-core liquid crystals

Cited by 10 publications

References 24 publications

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Photoinduced modulation of refractive index in Langmuir-Blodgett films of azo-based H-shaped liquid crystal molecules

Nanoscale Structure of Langmuir–Blodgett Film of Bent-Core Molecules

Contact Info

Product

Resources

About