本論文合成一系列4-(4-鹵化烷氧基)-4’-烷氧基羰基双苯偶氮化合物包括不同長度的酯鏈或烷氧鏈，或在烷氧鏈末端接上不同鹵素取代基等衍生物用以探討液晶性質。這些化合物經由偏光顯微鏡鑑定其液晶光學紋理皆為層列相A且用微差式熱掃瞄卡計鑑定其液晶溫度範圍。
當此系列偶氮苯衍生物為相同烷氧鏈長時，酯鏈長度越長液晶範圍也增大，以R=C8H17,R=C10H21最佳。當酯鏈長度固定R=C8H17，而改變烷氧鏈長度時，碳數n分別為1,2,3,4,10和12，其中n=1不具液晶相，n=2,3,10,12皆為單向變型液晶，然較長的烷氧鏈反而相轉移溫度變窄；n=4液晶效果最佳，為雙向互變型液晶。由結果推論穩定的液晶相需軟端的長鏈及硬端的芳香環有適當的比例。
比較當烷氧鏈末端未接鹵素取代基和烷氧鏈末端接鹵素取代基X=Cl,Br,I結果發現，有鹵素取代基明顯地液晶溫度範圍較大，但隨著鹵素原子大小增大，液晶效果變差，究其原因可能是有較大的鹵素時，分子間間距變大，使得分子間作用力變小所致。

Abstract
A series of azobenzene derivatives of 4-(4-haloalkoxyl)-4’alkoxy
-carbonylazobenze with different length of ester side chains and alkoxy side chains,and different halogen substituent on the end of alkoxy side chains were synthesized. These azobenzene derivatives synthesized in this investigation were found to have the textures of SmA liquid crystals by using polarized optical microcope(POM) .While their phase transition temperatures ranges changed with carbon chain length as well as the size of halogen.
When these azoenzene derivatives have the same length of alkoxy side chains,as the length of ester side chains are longer, liquid crystal properties are better. R=C8H17 and C10H21 have the longest phase transition temperatures ranges of all liquid crystals prepared.
When these azobenzene derivatives have the same length of ester side chains R=C8H17,and the length of alkoxy side chain is varied with carbon numbers of n=1,2,3,4,10,12 ,The results show when n=1,it isn’t a liquid crystal. Carbon numbers of n=2,3,10,12 are monotropic liquid crystalline and have narrow phase transition temperature ranges. Carbon numbers of n=4 is the best liquid crystal found.
When H on the end of alkoxy side chains is substituted with X=Cl,Br,I varied,the properties of liquid crystal with halogen substituent normally are better liquid crystallines. However,when the size of halogen is bigger, liquid crystal properties are poorer. From a regular decrease in the intermolecular forces with increasing size of the substituent, leading to a corresponding increase in the mean intermolecular space separation.

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