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URN etd-0613112-101142 Statistics This thesis had been viewed 2020 times. Download 1033 times. Author Hsien-chen Huang Author's Email Address No Public. Department Chemical Engineering Year 2011 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 43 Title Study on the Binary Mixtures of Blue Phase Liquid Crystals Keyword Binary Mixtures Blue Phase Liquid Crystals Blue Phase Liquid Crystals Binary Mixtures Abstract A few of liquid crystal materials exhibiting blue phases have been reported in a single compound, moreover, the blue phases in the materials possess a very small temperature range (cal.1-2℃), mainly because of the blue phases are frustration phases. Thus, the relationship between molecule structure and the formation of blue phases has never been established. Neither the liquid-crystal mixture technique has been explored and studied yet. The main objective of this experiment work is to explore whether the binary mixture of the blue phase materials could enhance the thermal stability of the blue phase.
There are two methods using for mixing the liquid crystal material for the present work. One method is mixing the compounds by solvent; two compounds with appropriate percentage are first placed in a small sample vial and properly mixed by adding CCl2. The mixture is well mixed ultrasonically for about 15 minutes, and then placed in the vacuum oven for about 20 minutes until the solvent is completely evaporated. The well mixed sample was then placed in hot stage and investigated under Polarizing Microscope (POM) to identify the liquid crystal phases and the phase transition temperature of the mixture. The other method is a contact method by placing appropriate amount of two chiral compounds onto the glass substrate, closed to two sides of the cover slip. The glass substrate was heated to allow the compounds diffuse to contact each other by capillary action, forming a contact interface, and then investigate the textures by POM under proper temperature.
The results from mixing the percentage of 1:1 of the blue phase liquid crystal IR(7) as the reference with other structurally different blue phase liquid crystal materials, show that the temperature ranges of blue phases are not increasing, in contrast, the temperature ranges of blue phases are decreasing or even disappeared.
The results of the mixture of enantiomers IR(7)/IS(7) show that when mixing them with the same proportion, the blue phase disappeared and nametic phase formed instead because of the disappearance of chirality.
The results of mixing two compounds, that have the same core structure but different alkyl-chain of chiral end, show that the temperature range of blue phases only has little changes (3~5℃) but has no significant trend.
The above results can be concluded that it is imposable to enhance the temperature range of blue phases by using mixing technique. That is to say, the attempt to achieve the blue phase mixture for manufacturing the blue phase display by using mixing blue phase materials will be in van. This might result from the blue phases that are consisted of lattice structure, such that when mixing compounds of different structures, the lattice structure of blue phases could be destroyed. The details of forming blue phase by mixing require the physicists to explore in the future.
Advisor Committee Shune-Long Wu - advisor
Files Date of Defense 2012-06-01 Date of Submission 2012-07-10