Homogeneously aligned liquid crystal molecules on unidirectional buckle pattern of polyurethane films

Hae Chang Jeong, Jonghoon Won, Ju Hwan Lee, Hyo Young Mun, Dong Hyun Kim, Dong Wook Lee, Byeong Yun Oh, Jeong Min Han, Dae Shik Seo

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Abstract

We present the fabrication of an anisotropic structure on a polyurethane (PU) film for aligning liquid crystal (LC) molecules with ion beam (IB) irradiation at an incident angle. The obtained anisotropic structure assembles the LC cells in a layer that aligns LC molecules uniformly. Polarised optical microscopy images of an LC cell fabricated with IB-irradiated PU were captured to confirm the LC alignment state and compared with those fabricated with non-treated PU. To analyse the effects of the IB irradiation, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy were used to investigate the chemical and morphological modifications, respectively. IB irradiation modifies the chemical structure of PU, which indicates that a new skin layer is formed on the PU films. This skin layer generates an in-plane compressive strain, thereby creating buckles on the PU films. Simultaneously, the physical collision of the reactive Ar+ ions during IB irradiation induces a directional strain on the surface, thereby forming a unidirectional structure of buckles along the direction of IB irradiation. The PU film annealed at 200°C showed the high average transmittance of 88.9%, which is appropriate as an alignment layer.

Original languageEnglish
Pages (from-to)95-101
Number of pages7
JournalLiquid Crystals
Volume45
Issue number1
DOIs
Publication statusPublished - 2018 Jan 2

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Jeong, H. C., Won, J., Lee, J. H., Mun, H. Y., Kim, D. H., Lee, D. W., Oh, B. Y., Han, J. M., & Seo, D. S. (2018). Homogeneously aligned liquid crystal molecules on unidirectional buckle pattern of polyurethane films. Liquid Crystals, 45(1), 95-101. https://doi.org/10.1080/02678292.2017.1300955