Nonlinear optical spectroscopic studies of polymer surfaces for liquid crystal alignment: Photo-irradiated polyimide and rubbed polystyrene surfaces

Masahito Oh-e, Seok Cheol Hong, Y. R. Shen

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Surface specific sum-frequency vibrational spectroscopy (SFVS) and second-harmonic generation (SHG) were used to study the structures of polymer surfaces modified by linearly polarized UV irradiation or mechanical rubbing. The spectroscopic results show that the surface anisotropy of a polyimide surface resulting from bond breaking by linearly polarized UV irradiation is extremely small compared to a rubbed surface. On a rubbed polystyrene surface, the phenyl sidegroups are well aligned by rubbing in the direction perpendicular to rubbing but tilt from the surface normal with a broad distribution.

Original languageEnglish
JournalMolecular Crystals and Liquid Crystals
Volume412
DOIs
Publication statusPublished - 2004 Dec 1
Externally publishedYes

Fingerprint

Liquid Crystals
Polystyrenes
polyimides
Polyimides
Liquid crystals
polystyrene
Polymers
liquid crystals
alignment
polymers
Irradiation
Vibrational spectroscopy
irradiation
Harmonic generation
harmonic generations
Anisotropy
anisotropy
spectroscopy

Keywords

  • Interface
  • Liquid crystal
  • Nonlinear optics
  • Polyimide
  • Sum-frequency generation
  • Surface
  • Vibrational spectroscopy

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

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AU - Oh-e, Masahito

AU - Hong, Seok Cheol

AU - Shen, Y. R.

PY - 2004/12/1

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AB - Surface specific sum-frequency vibrational spectroscopy (SFVS) and second-harmonic generation (SHG) were used to study the structures of polymer surfaces modified by linearly polarized UV irradiation or mechanical rubbing. The spectroscopic results show that the surface anisotropy of a polyimide surface resulting from bond breaking by linearly polarized UV irradiation is extremely small compared to a rubbed surface. On a rubbed polystyrene surface, the phenyl sidegroups are well aligned by rubbing in the direction perpendicular to rubbing but tilt from the surface normal with a broad distribution.

KW - Interface

KW - Liquid crystal

KW - Nonlinear optics

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KW - Sum-frequency generation

KW - Surface

KW - Vibrational spectroscopy

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