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Updated: Jul 10, 2026
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Planar anchoring and surface melting in the smectic-A phase.
Emmanuelle Lacaze1, Jean-Philippe Michel, Michel Alba
1INSP, CNRS UMR-7588, Universités Pierre et Marie Curie-Paris 6, 140 Rue de Lourmel, F-75015 Paris, France. emmanuelle.lacaze@insp.jussieu.fr
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2007
Summary
Ultrathin 8CB films on MoS2 substrates show anchoring transitions. A distinct intermediate nematic film influences anchoring energy, particularly for strong anchoring conditions.
Area of Science:
- Materials Science
- Surface Science
- Condensed Matter Physics
Background:
- Understanding interfacial phenomena in ultrathin liquid crystal films is crucial for advanced material applications.
- The interaction between liquid crystals and inorganic substrates dictates film behavior and properties.
- 8CB (4-octyl-4'-cyanobiphenyl) is a well-studied liquid crystal exhibiting various phases.
Purpose of the Study:
- To investigate the anchoring behavior of ultrathin 8CB films on molybdenum disulfide (MoS2) substrates.
- To determine the smectic anchoring energy at the 8CB-MoS2 interface.
- To explore the influence of film thickness and substrate interactions on liquid crystal phase transitions and anchoring.
Main Methods:
- Fabrication and characterization of ultrathin 8CB films on MoS2.
- Analysis of anchoring transitions using surface-sensitive techniques (e.g., ellipsometry, X-ray reflectivity).
- Thermodynamic modeling to determine anchoring energies and study interfacial phenomena.
Main Results:
- Observed anchoring breakage in 60-nm-thick 8CB films, transitioning from planar to homeotropic anchoring at the air interface.
- Quantified the 8CB-MoS2 smectic anchoring energy.
- Identified an intermediate planar anchoring film with melted smectic layers near the MoS2 substrate for films thinner than 60 nm.
- Demonstrated that deformations in this intermediate nematic film can drive the anchoring energy for strong anchoring scenarios.
Conclusions:
- The study reveals a thickness-dependent anchoring transition in 8CB films on MoS2.
- An intermediate nematic film plays a critical role in determining the overall anchoring behavior and energy.
- The findings offer insights into interfacial physics of liquid crystals on inorganic substrates, relevant for device design and fundamental understanding.
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