Design of Amphiphilic Zwitterions Forming Liquid-Crystalline Phases and Effects of Lithium Salt Addition on Their Phase Behavior

作者：Matsumoto Takuro; Ichikawa Takahiro; Sakuda Junji; Kato Takashi; Ohno Hiroyuki^*

来源：Bulletin of the Chemical Society of Japan, 2014, 87(7): 792-796.

DOI：10.1246/bcsj.20140049

We prepared pyridinium-based amphiphilic zwitterions and examined their liquid-crystalline (LC) phase behavior in the presence and absence of lithium salts. Addition of lithium salts induced nanosegregated LC phases such as bicontinuous cubic phase and smectic phase depending on the anion species of the lithium salts. For example, an equimolar mixture of dodecylcarbamoyl-1-(4-sulfobutyl)pyridinium betaine and lithium bis(trifluoromethanesulfonyl)imide (LiTf2N) exhibited a bicontinuous cubic phase between 40 and 100 C. The exhibition of these nanosegregated phases was attributed to the formation of an ionic liquid-like ion pair composed of the pyridinium cation and the Tf2N anion. The preferential interaction between the pyridinium cation and the Tf2N anion was confirmed with Raman spectroscopic measurement. Moreover, the amphiphilic zwitterions were found to show not only thermotropic LC behavior but also lyotropic LC behavior in the presence of polar solvents such as protic ionic liquids. The results presented here indicate that the combination of amphiphilic zwitterions and suitable additive ions is a potential method to construct nanostructured LC materials showing tuneable phase behavior.

• 出版日期2014-7-15