A General Control Strategy to Micropattern Topological Defects in Nematic Liquid Crystals Using Ionically Charged Dielectric Surface. Issue 11 (3rd May 2021)

• Record Type: Journal Article
• Authors: Sasaki, Yuji; Takahashi, Junnosuke; Yokokawa, Shunsuke; Kikkawa, Takuho; Mikami, Ryota; Orihara, Hiroshi
• Is Part Of: Advanced materials interfaces. Volume 8:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-03
• Subjects: area‐selective deposition -- liquid crystals -- pattern formation -- self‐organization of microstructures -- surface modification; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202100379
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: Tailoring self‐organized nano/microstructures in soft materials is crucial for exploiting intrinsic functional properties toward emerging applications. Engineered topological defects in liquid crystals are interesting for electro‐optical devices as well as for soft actuators morphing surface. Despite the promising potential, there are currently few bottom‐up methods for positioning a large number of defects periodically over a large area. It is highly challenging to develop essential techniques for achieving high‐throughput fabrication with simple procedure. Using ultraviolet/ozone treatment, herein we present a general and robust strategy to produce the surface that can be a platform for a self‐organized micropattern of topological defects in nematic liquid crystals, irrespective of the chemical structure of compounds including polymerizable monomers. The micropattern formation is controllable by applying area‐selective surface modification, which dramatically improves the fabrication efficiency. By low frequency impedance spectroscopy, the distinctive frequency dependence of the apparent threshold voltage at the micropattern formation is experimentally assigned to a unique reorientational response which occurs when a dielectric surface is charged by ionic additives. This characterization provides crucial guidance in further engineering self‐organized topological defects in liquid crystals. Abstract : A general and robust method for micropatterning self‐organized topological defect networks in nematic liquid crystals is achieved by using ultraviolet/ozone surface treatment. A simple area‐selective modification technique dramatically improves the fabrication efficiency, resulting in large‐scale tunable self‐organized microstructures. Low‐frequency impedance spectroscopy unveils that the micropattern formation is a unique reorietational transition taking place on the ionically charged dielectric surface.