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Author Lu, J. ♦ Deshpande, S. V. ♦ Gulari, E. ♦ Kanicki, J. ♦ Warren, W. L.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ CHEMISTRY ♦ LIQUID CRYSTALS ♦ PHOTOCHEMICAL REACTIONS ♦ ULTRAVIOLET RADIATION ♦ FILMS ♦ ALIGNMENT ♦ PHOTOELECTRON SPECTROSCOPY ♦ ELECTRON SPIN RESONANCE ♦ CHEMICAL BONDS ♦ OXIDATION ♦ POLYIMIDES
Abstract Ultraviolet light induced changes in polyimide liquid-crystal alignment films were investigated. Infrared, UV-visible, x-ray photoelectron spectroscopy, and electron-spin-resonance measure- ments indicated that bond breaking and subsequent oxidation reactions occur in polyimide films (SE7210, OCG284, DuPont 2555 and 2540) during the broadband UV illumination in air. Mechanical rubbing has no effect on the optical and magnetic properties but it causes the removal of the UV-exposed film. Capacitance{endash}voltage measurements indicate that there is a slight decrease in dielectric constant and creation of net negative charges in the film after UV exposure. Sur- face tension of polyimide films before and after UV illumination and changes in the pretilt angle of the polyimide surface following UV exposure have also been studied. The decrease in pretilt angle following UV illumination is attributed to an increase in surface tension. Our results indicate that a simple UV technique can be used to achieve domain divided liquid-crystal pixel electrode design with improved viewing characteristics. {copyright} {ital 1996 American Institute of Physics.}
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-11-01
Publisher Department Sandia National Laboratory
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 80
Issue Number 9
Organization Sandia National Laboratory


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