Rubbing-induced molecular alignment on an orienting layer of polyimide with and without alkyl side chains

Jung Y. Huang, Jie S. Li, Youe S. Juang, Shu Hsia Chen

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29 Scopus citations

Abstract

The rubbing-induced molecular alignment on a surface of polyimide with and without branched alkyl side chains was investigated with optical phase retardation measurement, atomic force microscopy (AFM), and second-harmonic generation (SHG). Our AFM results suggest that the rubbing-induced microgrooves play a minor role in aligning liquid crystal (LC) molecules. From the SHG studies, the detailed in-plane distribution of a LC monolayer on rubbed polymers was deduced, and the polar angle of the LC molecules was found to vary with the rubbing strength exerted on an alkyl-branched polymer. The polar angle of the LC monolayer on an alkyl-branchless main- chain polyimide film was observed to be independent of the rubbing strength. We propose a simple molecular model to reconcile these experimental results.

Original languageEnglish
Pages (from-to)3163-3169
Number of pages7
JournalJapanese Journal of Applied Physics
Volume34
Issue number6R
DOIs
StatePublished - 1 Jan 1995

Keywords

  • Atomic force microscopy
  • Liquid crystal
  • Optical second-harmonic generation
  • Pretilt angle
  • Rubbed polymer

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