羥丙基纖維素/液態離子之溶凝膠轉換及液晶相研究

The Study of Sol/Gel Transition and Liquid Crystal in Hydroxypropyl Cellulose/Ionic Liquid

吳伯賢(Po-Shien Wu)

指導教授 ： 芮祥鵬

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2007年)

摘要

許多的生物聚合物在水和一般的有機溶劑中是不易溶解的。近來，有研室顯示生物聚合物在離子液中是可溶解的。離子液體引起工業的觀注，特別是綠色化學。以離子液體溶解纖維素使得纖維素被廣泛地利用。因其符合綠色化學的兩個主要的原則：符合環境保護要求的溶劑和可回收的原料。
此研究中，我們準備離子液體(1-Butyl-3-methylimidazolium acetate)當成溶劑用以溶解纖維素(HPC)。羥丙基纖維素於凝膠狀態有液晶相的特性，依它的形成機制為液向型(lyotropic)液晶而液向型液晶表現方式是由濃度控制，依分子排列方式屬於膽固醇(cholesteric)液晶。由於羥丙基纖維素的結構會隨著加熱而發生構形轉變，並由低溫的異向性加熱到一定溫定後形成同向性。
藉著溶膠/凝膠轉換和液晶轉換來研究羥丙基纖維素離子溶液。本研究利用SR5流變儀試著找出其溶膠/凝膠狀態轉換臨界濃度，並分別於不同濃度及溫度狀態下做流變黏彈性質探討。而試著以偏光顯微鏡(POM)及加熱板(Hot stage)來觀察出纖維素液晶的溫度範圍。由結果發現不論是黏度或滯後性其在異向區會受結構影響而在同向區則受溫度影響。

關鍵字

流變學 ； 羥丙基纖維素 ； 溶膠 ； 凝膠 ； 液晶

並列摘要

Many biological polymers are insoluble in both water and general organic solvents. Recently, it was reported that biological polymers are soluble in the ionic liquids. Ionic liquid (IL) has gained industry attention, especially in green chemistry. Dissolution of cellulose with ionic liquids allows the comprehensive utilization of cellulose by combining two major green chemistry principles: using environmentally preferable solvents and bio-renewable feed-stocks.
In this study, we have prepared ionic liquids(1-Butyl-3-methylimidazolium acetate) as solvents for hydroxypropyl cellulose(HPC). Hydroxypropyl cellulose in gel condition still have the properties of liquid crystal. Hydroxypropyl cellulose, which possesses lyotropic properties,and it was confirmed by optical studies that showed samples in this region to consist of a cholesteric liquid crystalline phase dispersed in an isotropic phase. The structure of hydroxypropyl cellulose have changed with heating, it is anisotropic in low temperature , but it is become isotropic with heating until the special temperature .
The HPC/IL solutions is investigated by means of the sol/gel transition and liquid crystal transition. The rheometry SR5 was performed in this study for trying to find the sol/gel transition and measuring the viscoelasticities at different concentrations and temperature respectively. The polarized optical microscopy and hot stage were performed in this study for trying to find the temperature range of hydroxypropyl cellulose’s liquid crystal. Accroding to the conclusion, the viscosity and hysteresis are influence by structure in anisotropic , but in isotropic are influence by temperature.

並列關鍵字

rheology ； hydroxypropyl cellulose ； sol ； gel ； liquid crystal

參考文獻

[33] 張雅婷，溫度敏感型甲基纖維素水膠之成膠行為與間葉幹細胞在其中之生物相容性，碩士論文，元智大學生物科技暨生物資訊研究所，桃園，2006。

[4] T. Tixier, M. Heppenstall-Butler, and E.M. Terentjev, "Stability of cellulose lyotropic liquid crystal emulsions," The European Physical Journal E, vol. 18, 2005, pp. 417-423.

[7] S. Zhu, Y. Wu, O. Chen, Z. Yu, C. Wang, S. Jin, Y. Dinga, G. Wu, "Dissolution of cellulose with ionic liquids and its application: a mini-review," Green Chemistry, vol. 8, 2006, pp. 325-327

[8] A.P. Abbott, T.J. Bell, S. Handa, B. Stoddart, "Cationic functionalisation of cellulose using a choline based ionic liquid analogue," Green Chemistry, vol. 8, 2006, pp. 784-786

[9] H. Zhang, J. Wu, J. Zhang, J. He, "1-Allyl-3-methylimidazolium chloride room temperature ionic liquid: A New and Powerful Nonderivatizing Solvent for Cellulose," Macromolecules, vol. 38, no. 20, 2005, pp. 8272-8277.