Authors: T.J. Lee, S.G. Hahm, S.W. Lee and M. Ree
Affilation: Pohang University of Science and Technology, Korea
Pages: 166 - 168
Keywords: anchoring energy, liquid crystal, alignment layer, PVCi
At present, a rubbing process using a fabric is the only technique adopted in the LC display industry to treat PI film surfaces for the mass-production of flat-panel LC display devices. However, this process has some shortcomings. The search for new methods that do not suffer from the shortcomings of the rubbing process has led to the development of several approaches to polymer alignment layer surface treatment based on irradiation of the polymer with linearly polarized ultraviolet light (LPUVL). In the present study, we chose poly(vinyl cinnamate) (PVCi) as a model alingnment layer material, and processed its thin films by various combinations of rubbing and LPUVL exposure. The films were investigated in detail in aspects of film surface morphology, polymer chain orientation, LC alignment, and LC anchoring energy. Depending on the surface treatment methods and their sequences, the orientational director of liquid crystals was varied. The anchoring energy of liquid crystals at the treated filmsurfaces was found to range 10-5 to 10-7 J/m2. All the results will be discussed in details with considering the chemical nature of the film and of the liquid crystals, as well as the surface morphologies and the process parameters.