| Summary: | 博士 === 國立清華大學 === 化學工程學系 === 99 === Part 1 Photo-Induced Nano-Porosity of tert-Butoxycarbonyl Acrylic Photosensitive Material with Low Dielectric Constant
We have reported a photosensitive system having low dielectric constant with nanoporous. The photosensitive system is patternable and the nano-porosity is generated through the combination of photo exposure and thermal treatment. Nanoporous were formed in a photosensitive material to reduce its dielectric constant. A tert-butoxycarbonyl (t-BOC) containing acrylic copolymer can be activated as a photosensitive material via photochemical reactions. Iodonium salt as a photo acid generator (PAG) was exposed to ultraviolet light with a wavelength of under 365nm to form the corresponding bronsted acid. The side chains of t-BOC were cleaved by this bronsted acid to yield isobutylene and acrylic acid groups. The small molecules of isobutylene thus formed were further heated in the polymer matrix to generate nanoporous. Notably, the t-BOC content and heat affect the dimensions and number of nanoporous. The dielectric constant decreased as the density of nanoporous increases. The formation of nanoporous was observed by TEM and SEM. Also, the mechanisms of formation of nanoporous and their effects on the dielectric constant were studied. The nanoporous photosensitive material can thus be applied in integrated circuits and the new generation of liquid crystal displays.
Part 2 Non-contact Mode Liquid Crystal Alignment Film of Acrylic Photosensitive Material
We have developed a new photosensitive material, which is applicable for photo-induced alignment layer for liquid crystal display. The synthesis and characterization of bis-methacrylic derivatives of p-aminophenol was explored. We were able to control the molecular weight of the dimethacrylate based photosensitive polymer via free radical polymerization. The polymerization selectivity of the double bonds in homopolymer could be verified with the solid state NMR.
We have also developed a series of fluorinated dimethacrylate copolymers which are applicable for plasma treatment and useful for photo induced liquid crystal alignment layer. Our work covered the synthesized derivatives of alignment materials, characterized properties of the pretilt angle, and uniformity of liquid crystal alignment layer. The surface properties of alignment film and the liquid crystal pretilt angle were tailored by fluorinated dimethacrylate copolymer.
The formation of orientational microgrooves on polymer films via anode layer thruster (ALT) plasma treatment was reported. The surface morphology of the plasma-treated polymer films was examined by using atomic force microscopy (AFM). The results show that the microgrooves are aligned periodically in the scan direction of the plasma beam. The microgrooves become more pronounced as the number of scans increases. The depth of the microgrooves and the azimuthal anchoring energy also increase with the number of the plasma beam scans.
In addition, excellent alignment uniformity has been achieved by using the photo-induced process and the anode layer thruster plasma treatment. We find that the pretilt angle of LC cell by plasma treatment is higher than that of polarized UV treatment. The azimuthal anchoring energy measured is around 10-4 J/M2 by using the plasma treatment. The dimethacrylate-based photosentive polymer can be applied to the photo induced and plasma treated LC alignment layer.
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