含寡聚(乙烯氧基)側鏈之曲棍形液晶分子合成及性質研究

Synthesis and properties of hockey stick liquid crystals with oligo(ethyleneoxy) side chain

姚世逸(Shi-Yi Yao)

指導教授 ： 余良杰

淡江大學/理學院/化學學系碩士班/碩士(2010年)

https://doi.org/10.6846/TKU.2010.00825

摘要

本研究的主要目的為合成十系列不同的苯環數及不同側鏈之曲棍型液晶分子，討論分子結構在側鏈上含寡聚乙烯氧基以及不同的連接基，對液晶相及相關溫度的影響，並探討各種液晶相之相關性質。

　　實驗中發現將曲棍形液晶分子之側鏈修飾成乙烯氧基且連接基為醚基時，熔點上升，又或將側鏈之連接基修飾為酯基時，不利於N相之形成，卻能有效降低熔點及擴大液晶相範圍。

　　在電性實驗方面SmC相及SmCa相能觀察到兩種不同的光學性質區塊(domain)，旋轉樣品時兩區塊顏色互換，且SmC在增加電場強度時有顏色變化，SmCa相增加電場時類似pitch band的紋路減少，N相在較高溫時增加電場出現顏色變化，在較低溫時增加電場顏色變化不明顯，且出現擾動現象。

關鍵字

曲棍形 ； 液晶 ； 乙烯氧基

並列摘要

Ten series of hockey stick molecules were synthesized with different ethyleneoxy side chains and aromatic cores. Mesophase properties of these hockey stick mesogens were studied by polarizing optical microscopy, differential scanning calorimetry, powder X-ray diffraction, and electric field effect.

As compared with the meta-positioned hydrocarbon chain analogues, the ethyleneoxy derivatives exhibited slightly smaller mesophase ranges, mainly due to the narrowing of the smectic phase thermal ranges. For the ether and ester linked ethyleneoxy side chain derivatives, ester linked derivatives showed appreciable lowering of melting point but without anticlinic smectic phase.

The optical and electric-field effect of the synclinic and anticlinic smectic phases, SmC and SmCa, resemble those of known hockey stick mesogens, i.e., two types of domains with opposite tilting directions and color exchange with opposite rotation of sample. Color of the SmC changed with increasing electric field strength, the pitch-band-like lines of the SmCa domains diminished with field strength.

Smectic B phase existed, from X-ray diffraction and optical appearance, for two of the newly synthesized four-ring skeleton hockey stick mesogens.

並列關鍵字

Hockey stick ； liquid crystal ； ethyleneoxy

參考文獻

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