Surface modification of a poly(ethylene-co-vinyl acetate) layer by ion beam irradiation for the uniform alignment of liquid crystals

Dong Wook Lee, Ju Hwan Lee, Eun Mi Kim, Gi Seok Heo, Dong Hyun Kim, Jin Young Oh, Yang Liu, Dae Shik Seo

Research output: Contribution to journalArticlepeer-review

Abstract

The post-processing of a poly(ethylene-co-vinyl acetate) (PEVA) film by ion-beam (IB) irradiation is described herein for use as a liquid crystal (LC) alignment layer. Various film curing temperatures are investigated in order to achieve a stable film prior to IB irradiation, and a uniform and homogeneous LC alignment with superior optical transparency is obtained at a curing temperature of 130 °C. The chemical and morphological effects of IB irradiation are further examined by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Although the surface morphology exhibits a random pattern, the IB irradiation is found to modify the chemical characteristics of the PEVA surface by simultaneously inducing van der Waals forces and strong dipole-dipole interactions with the LCs, thus leading to unidirectional LC alignment. In addition, LC cells are fabricated from the IB-irradiated PEVA films, and the LC alignment state is confirmed by polarized optical microscopy and pre-tilt angle measurements. Further, the high transparency of the deposited PEVA film compared to that of ITO-coated glass is demonstrated via transmittance measurement. In view of this superior performance, the IB-irradiated PEVA film is a promising alternative for advanced LC displays.

Original languageEnglish
Article number116700
JournalJournal of Molecular Liquids
Volume339
DOIs
Publication statusPublished - 2021 Oct 1

Bibliographical note

Funding Information:
This research was supported by the National Research Foundation of Korea (grant No. 2021-11-0383 ).

Publisher Copyright:
© 2021 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Materials Chemistry

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