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Internal structure visualization and lithographic use of periodic toroidal holes in liquid crystals

Nature Materials volume 6, pages 866–870 (2007)Cite this article

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 science1 and nanotechnology2,3,4. So far, several distinct organic building blocks—including colloids, block copolymers and surfactants—have been examined as potential materials for the creation of lithographic templates1,5,6. 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.

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Figure 1: Liquid-crystal material and model of confined geometry.
Figure 2: The dense population of TFCDs in the microchannels.
Figure 3: Direct visualization of the internal structure of the TFCDs.
Figure 4: Trapped fluorescent silica particles in TFCDs.

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Acknowledgements

This work was supported by the National Research Laboratory Program of the Korea Science and Engineering Foundation (KOSEF), the Basic Research Program (R01-2005-000-10456-0), the KRF (2005-908-D00018), the Korea Health 21 R&D Project of MOHW and the CUPS-ERC program. X-ray experiments were carried out at PLS were supported in part by MOST and POSCO. M.C.C. received partial support from the Korean Research Foundation Grant KRF-2005-2214-C00202. O.D.L. acknowledges the support of a NSF DMR 0504516 grant.

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Author notes

  1. Dong Ki Yoon and M. C. Choi: These authors contributed equally to this work

Authors and Affiliations

  1. Department of Chemical and Biomolecular Engineering (BK-21), Organic Opto-Electronic Materials Lab, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea

    Dong Ki Yoon, Yun Ho Kim & Hee-Tae Jung

  2. Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea

    M. C. Choi & Mahn Won Kim

  3. Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA

    M. C. Choi

  4. Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA

    Yun Ho Kim & Oleg D. Lavrentovich

Authors
  1. Dong Ki Yoon
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  5. Oleg D. Lavrentovich
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  6. Hee-Tae Jung
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Corresponding author

Correspondence to Hee-Tae Jung.

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Supplementary materials and figures S1-S10 (PDF 1934 kb)

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Yoon, D., Choi, M., Kim, Y. et al. Internal structure visualization and lithographic use of periodic toroidal holes in liquid crystals. Nature Mater 6, 866–870 (2007). https://doi.org/10.1038/nmat2029

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