Related Experiment Video
Updated: Jun 6, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Controlling liquid crystal alignment using photocleavable cyanobiphenyl self-assembled monolayers
Panida Prompinit1, Ammathnadu S Achalkumar, Jonathan P Bramble
1Molecular and Nanoscale Physics, School of Physics and Astronomy, Centre for Molecular Nanoscience (CMNS), and Institute of Microwaves and Photonics, University of Leeds, Leeds LS2 9JT, United Kingdom.
ACS Applied Materials & Interfaces
|November 13, 2010
Summary
Researchers developed novel photo-patternable self-assembled monolayers for precise liquid crystal alignment. These cyano-biphenyl thiolate surfaces enable controlled positioning and confinement of focal conic domains in smectic-A phases.
Area of Science:
- Materials Science
- Surface Chemistry
- Liquid Crystal Physics
Background:
- Self-assembled monolayers (SAMs) are crucial for surface functionalization.
- Controlling liquid crystal alignment on surfaces is essential for device applications.
- Photo-patternable surfaces offer precise control over molecular organization.
Purpose of the Study:
- To develop novel cyano-biphenyl-based thiolate SAMs for liquid crystal alignment.
- To investigate photo-induced surface modification for tunable alignment.
- To demonstrate control over focal conic domain formation using patterned SAMs.
Main Methods:
- Synthesis of ortho-nitrobenzyl protected carboxylic acid functionalized thiolate molecules.
- Fabrication of SAMs on surfaces.
- Photo-patterning using soft UV (365 nm) irradiation.
- Surface characterization using wetting, X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared reflection absorption spectroscopy (FTIRAS), and ellipsometry.
- Analysis of liquid crystal alignment and focal conic domain formation.
Main Results:
- High photolysis yields (>90%) achieved upon UV irradiation, converting protected groups to carboxylic acids.
- Successful generation of patterned SAMs promoting both homeotropic and planar alignment.
- Demonstrated suitability of patterned SAMs for controlled alignment of calamitic liquid crystals.
- Controlled positioning and size confinement of focal conic domains (FCDs) in the smectic-A phase.
Conclusions:
- Novel photo-patternable SAMs based on cyano-biphenyl thiolates enable switchable surface alignment.
- Photo-induced deprotection allows for precise patterning of surface chemistry and liquid crystal alignment.
- Patterned SAMs offer a versatile platform for controlling liquid crystal phases, including FCDs.
