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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Effect of substrate geometry on liquid-crystal-mediated nanocylinder-substrate interactions
David L Cheung1, Michael P Allen
1Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom. david.cheung@warwick.ac.uk
The Journal of Chemical Physics
|December 3, 2008
Summary
Researchers studied liquid crystal (LC) interactions between nanoparticles and structured surfaces. They found that by altering groove dimensions, the interaction could be tuned from repulsive to attractive, impacting nanoparticle positioning.
Area of Science:
- Soft Matter Physics
- Materials Science
- Nanotechnology
Background:
- Liquid crystals (LCs) exhibit complex behaviors due to their anisotropic molecular structure.
- Nanoparticle-surface interactions are crucial in various applications, including advanced materials and devices.
- Surface structuring can significantly influence the behavior of surrounding soft matter like LCs.
Purpose of the Study:
- To investigate the liquid crystal-mediated interaction between a cylindrical nanoparticle and a substrate with a rectangular groove.
- To understand how groove geometry affects the nanoparticle-LC-surface system's energetics and stability.
- To explore the tunability of nanoparticle-surface interactions by modifying surface structure.
Main Methods:
- Classical density functional theory (DFT) was employed to model the system.
- Simulations focused on the interaction between a cylindrical nanoparticle and a grooved substrate within a liquid crystal medium.
- System parameters, including groove width and depth, were systematically varied.
Main Results:
- Defect structures form in the liquid crystal near the groove in the absence of a nanoparticle.
- The LC-mediated interaction transitions from repulsive to attractive by adjusting groove width and depth.
- Interaction strength is maximized when groove dimensions are comparable to the nanoparticle size.
- Nanoparticle positioning is dependent on groove width: attraction to the center for narrow grooves and to sidewalls for wider grooves.
Conclusions:
- Surface structuring, specifically rectangular grooves, offers a method to control nanoparticle-liquid crystal interactions.
- The ability to switch interactions from repulsive to attractive highlights potential for directed self-assembly.
- Understanding these interactions is key for designing novel nanostructured materials and devices.
