| Summary: | 碩士 === 國立中山大學 === 化學系研究所 === 97 === Controlling the orientation of liquid crystal molecules in LC displays is extremely important for optimizing device performance. The method most commonly used in industry today involves rubbing the surface of the polymer-coated glass substrates used in the displays with a velvet cloth to create microscopic grooves. Berreman theory states that the liquid crystal molecules then align along the direction of the grooves. Alternatively, some literature shows that the friction caused by rubbing aligns the polymer chains in the surface layer which then attract and align the liquid crystal molecules along the direction of the chains. Even now, it is still unclear exactly how the process of rubbing the surface causes the liquid crystal molecules to align in an orderly manner.
This thesis describes a systematic study of the physical and chemical influence of the substrate on the alignment and orientation of liquid crystal molecules. We used Fourier Transform Infrared spectroscopy (FTIR) to identify surface chemistry, contact angle measurements to determine the surface energy, and atomic force microscopy (AFM) to observe the alignment of liquid crystal on the surfaces. In the course of this study, we have gained insight into how the physical and chemical properties of the surface affect the molecular arrangement in the solid-liquid interface. Our results can be applied not only to LCD technology, but more generally to biochips and biosensor devices.
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