Ion beam induced liquid crystal alignment properties of 4-alkylphenoxymethyl-substituted polystyrenes

Hyo Kang, Byoung Har Hwang, Hong Koo Baik, Daeseung Kang, Jong Chan Lee

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7 Citations (Scopus)


The pretilt angles of liquid crystals (LCs) can be controlled over the range 0° to 90° using ion beam treated 4-alkylphenoxymethyl-substituted polystyrene films as alignment layers, where the alkyl group is -(CH2)nH (n = 1, 2 or 4), by changing the ion beam irradiation time, incidence angle and energy. In general, LC cells made using a polymer film with a longer irradiation time, higher irradiation incidence angle with respect to the planar direction and higher irradiation energy exhibited lower pretilt angles relative to the planar direction. Furthermore, the LC cells produced using polymer films containing longer alkyl groups and a higher molar content of 4-alkylphenoxymethyl side groups exhibited greater pretilt angles under similar irradiation conditions. The LC alignment behaviour demonstrated good correlation with the wettability of the polymer films, due to fragmentation of the side groups on the polymer surfaces during ion beam irradiation. The electro-optical characteristics of the LC cells formed using these polymer films were similar to those produced using rubbed polyimide films, which are the LC alignment layers most commonly encountered.

Original languageEnglish
Pages (from-to)179-187
Number of pages9
JournalLiquid Crystals
Issue number2
Publication statusPublished - 2010 Feb

Bibliographical note

Funding Information:
We gratefully acknowledge the financial support provided by the Engineering Research Institute at Seoul National University; a government-funded MOEHRD Korea Research Foundation Grant (Basic Research Promotion Fund; Grant No. KRF-2008-314-D00112); and a Korea Science and Engineering Foundation (KOSEF) grant, also funded by the Korean government (Grant No. R2009-007711). Financial assistance has also been received from Soongsil University and from Samsung Electronics Co. Ltd.

All Science Journal Classification (ASJC) codes

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


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