Structural Transition of Cinnamate-Based Light-Responsive Ionic Liquids in Aqueous Solutions and Their Light-Tunable Rheological Properties.
Structural Transition of Cinnamate-Based Light-Responsive Ionic Liquids in Aqueous Solutions and Their Light-Tunable Rheological Properties.
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DOI：
10.1021/acs.langmuir.5b03854
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发表时间：
2016-01
期刊：
影响因子：
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通讯作者：
Jie Yang;Huiyong Wang;Jianji Wang;Xiaojia Guo;X. Pei
中科院分区：
文献类型：
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作者：
Jie Yang;Huiyong Wang;Jianji Wang;Xiaojia Guo;X. Pei
光敏蠕虫状胶束在微流体、光敏性流体和流变学控制等领域有着重要的应用。然而，仅由单一尾部表面活性剂形成的单组分光响应型蠕虫状胶束在文献中尚未见报道。本文通过UV-Vis光谱、粘度、流变学、电导率和低温电子显微镜研究了1-烷基-3-甲基咪唑反式邻甲氧基肉桂酸酯[CNMIM][OMCA](n=8，10，12，14，16)离子液体在水溶液中的自组装行为。首次发现，在所研究的单尾离子液体表面活性剂中，[C16mim][OMCA]在没有任何添加剂和光照的情况下，在水溶液中可以形成蠕虫状的胶束。然后，这些蠕虫状胶束能够在紫外光照射下转变为圆柱形胶束，从而使溶液的流变性显著可调。[C16mim][OMCA]阴离子从反式异构体到顺式异构体的光致异构化以及顺式异构体的相对亲水性和结构特征被认为是导致这种转变的原因。
Light-responsive wormlike micelles have important applications in fields such as microfluids, photoswichable fluids, and rheology control. However, single-component light-responsive wormlike micelles formed only from a single tail surfactant have not been reported in literature. In this work, self-assembly behavior of 1-alkyl-3-methylimidazolium trans-ortho-methoxycinnamate [Cnmim][OMCA] (n = 8, 10, 12, 14, 16) ionic liquids in aqueous solutions is studied by UV-vis spectroscopy, viscosity, rheology, conductivity, and cryo-TEM measurements. It is found for the first time that, among the single tail ionic liquid surfactants studied, [C16mim][OMCA] can form wormlike micelles in aqueous solutions without any additives and light irradiation. Then these wormlike micelles are able to transform into cylindrical micelles under UV light irradiation, resulting in significantly tunable rheological properties of the solutions. The photoisomerization of anion of [C16mim][OMCA] from trans- to cis-isomer as well as the relative hydrophilicity and structural feature of the cis-isomer are suggested to be responsible for such transition.