title: Internal structure visualization and lithographic use of periodic toroidal holes in liquid crystals.
abstract: The formation of a large-area ordered structure by organic molecular soft building blocks is one of the most exciting interdisciplinary research areas in current materials science and nanotechnology. So far, several distinct organic building blocks--including colloids, block copolymers and surfactants--have been examined as potential materials for the creation of lithographic templates. Here, we report that perfect ordered arrays of toric focal conic domains (TFCDs) covering large areas can be formed by semi-fluorinated smectic liquid crystals. Combined with controlled geometry, that is, a microchannel, our smectic liquid-crystal system exhibits a high density of TFCDs that are arranged with remarkably high regularity. Direct visualization of the internal structure of the TFCDs clearly verified that the smectic layers were aligned normal to the side walls and parallel to the top surface, and merge with the circular profile on the bottom wall surface. Moreover, we demonstrate a new concept: smectic liquid-crystal lithography. Grown in microchannels from a mixture of liquid-crystal molecules and fluorescent particles, TFCDs of the smectic liquid crystals acted as a template, trapping particles in an ordered array. Our findings pose new theoretical challenges and potentially enable lithographic applications based on smectic liquid-crystalline materials.
authors.affiliation: Organic Opto-Electronic Materials Lab, Department of Chemical and Biomolecular Engineering (BK-21), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
authors.forename: Dong Ki
authors.initials: DK
authors.lastname: Yoon
authors.forename: M C
authors.initials: MC
authors.lastname: Choi
authors.forename: Yun Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Mahn Won
authors.initials: MW
authors.lastname: Kim
authors.forename: Oleg D
authors.initials: OD
authors.lastname: Lavrentovich
authors.forename: Hee-Tae
authors.initials: HT
authors.lastname: Jung
mesh_terms: D050866:Liquid Crystals / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D012822:Silicon Dioxide