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研究生:陳吉福
研究生(外文):Jyi-Fwu Chen
論文名稱:以氫鍵鍵結之液晶相
論文名稱(外文):Mesophases Induced by Hydrogen Bonds
指導教授:余良杰
指導教授(外文):Liang-Jye Yu
學位類別:碩士
校院名稱:淡江大學
系所名稱:化學學系
學門:自然科學學門
學類:化學學類
論文種類:學術論文
論文出版年:1994
畢業學年度:82
語文別:中文
論文頁數:106
中文關鍵詞:氫鍵反鐵電性液晶重現向列相
外文關鍵詞:Hydrogen-Bondsantiferroelectricreentrant
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本研究探討氫鍵鍵結之液晶.由trans-4-alkoxy-4-stilbazole系列(CnSP,
質子接受者)分別和(1)3-alkoxybenzoic acid系列(3-CmOBA,質子提供者)
及(2)1,3,5-trihydroxybenzene(3OH,質子提供者)氫鍵鍵結而呈現液晶
相,氫鍵由紅外線證實.相轉移焓和紋理圖分別經由DSC測定及偏光顯微鏡
觀察.在3-CmOBA混合系統(莫耳比1:1),呈現雙向層相A和層相C,當3-
CmOBA之氧基數為偶數時,由層相C冷卻出現單向層相X.由層相A至層相C
之轉移焓小於0.06KJ/Mole,而層相C至層相X之轉移焓小於0.006 KJ/Mole.
由紋理圖及轉移焓的研究,此層相X極可能為反鐵磁性結構.推究原因,可能
是分子結構由直線形轉變為彎曲形所造成.在30H混合系統,莫耳比1:3(3
OH:CnOSP),n<=7時呈現雙向向列相; n=8時呈現向列相-層相A-reentrant
向列相之相變;n=9,10,12時呈現層相A和層相C.在C7OSP莫耳百分比73%以
下,也出現向列相-層相A-reen- trant向列相之相變.由向列相至層相A及
層相A至reentrant向列相之轉移焓皆小於0.04KJ/Mole.而氫鍵複合體緊靠
在一起的雙聚化現象是導致reentrant向列相發生的因素.
Hydrogn-bonded dimers of trans-4-alkoxy-4''-stilbazole
homologues(CnOSP,proton acceptors)and (1)3-alkoxybenzoic acid
homologues(3-CmObA,proton donor),(2)1,3,5-trihydroxy- benzene(3
OH,proton donor)exhibited mesophases. Hydrogen bonds were
confirmed by IR sepectroscopy. The enthalpies of phase
transsitions and texture of mesophases were studied by
Differential Scanning Calorimetry and Polarizing Optical
Microscopy, espectively. For the mixtures with 3-CmOBA as
proton donor(mole ratio1:1),enantiotropic SmA and SmC phase
were observed, and monotropic SmX phase (two-brush Schlieren
textures) was observe upon cooling the SmC phase when the
alkoxy chain consisted of even carbon numbers. The values of
transition enthalpy of SmA-SmC were smaller than 0.06KJ/mole
and those of SmC-SmX were smaller than 0.006KJ/mole. It was
suggested that the SmX could be the antiferrorlrctric phase on
the bases of optical textures and the transition enthapy. The
SmC-SmX transitions were attributed to be driven by the change
of straight-bend conformation of the hydrogen bonded complexes.
For the mixtures of 3OH and CnOSP with mole ratio 1:3 (3OH :
CnOSP),enantiotropic nematic phase were observed for n<=7, N-
SmA-reentrant N (Nr) were observed for n=8,and SmA and SmC were
observed for n=9,10,12. N-SmA-Nr transitions were alse observed
for mixture with C7OSP fraction less than 73%. The values of
transition enthalpy of N-SmA and SmA-Nr were smaller than
0.04KJ/mole. The occurrence of Nr phase was attributed to the
dimerization of the hydrogen bonded complexes.
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