【作者】 郑聪； 田彤彤； 于丽；

【Author】 Cong Zheng;Tongtong Tian;Li Yu;Key Laboratory of Colloid and Interface Chemistry,Shandong University;School of Chemistry and Chemical Engineering Qufu Normal University;

【机构】 山东大学胶体与界面化学教育部重点实验室； 曲阜师范大学化学与化工学院；

【摘要】 该工作合成了光响应的偶氮苯类表面活性剂—4-乙基偶氮苯-4’-己氧基三甲基溴化铵(azoTAB),并用其作为修饰剂,以离子液体—硝酸乙铵(EAN)为介质,构建了稳定持久可逆的液体-液晶光响应型界面。主要采用了偏光显微镜和紫外/可见近红外分光光度计等技术手段进行研究。结果表明,当azo TAB的浓度较高时,在紫外光和可见光的交替作用下,液晶的光学形貌和液晶分子在液-液界面上的排列方式分别发生了由暗到亮及由垂直到倾斜的交替变化。这主要是由于偶氮苯类表面活性剂分子的构型发生了顺反异构的可逆变化。相比于水-液晶界面,EAN几乎不蒸发的特性使得液晶的光学图片更加稳定,至少可在一个月内不用更换溶剂,并可实现多次光控可逆循环。因此离子液体-液晶界面具有更好的可控性、稳定性和重现性。本工作为进一步将基于离子液体的液晶传感器应用于生物分子检测奠定了实验基础。更多还原

【Abstract】 We synthesized a photoswitchable azobenzene-based ionic surfactant(4-ethylazobenzene-4’-(oxy-hexyl) trimethyl ammonium bromide, azoTAB) to act as a modifier and employed an ionic liquid(IL)-ethylammonium nitrate(EAN) as medium to construct the liquid-liquid crystals(LCs) interface. A persistent and reversible photoresponsive alignment of LCs at fluid interface was achieved. In this work, polarizing microscope and UV/Vis near-infrared spectrophotometer were used as mainly technical methods. When a high concentration of azoTAB is subjected to UV and visible light irradiation in sequence at the fluid interface, the alternating dark-to-bright shift of optical responses was observed, indicating the orientation of LCs alternatively changes from homeotropic to tilted alignment. It is caused by photoisomerization of the azobenzene group in azoTAB, which changes the structure of the surfactant from trans to cis configuration. Compared with aqueous-LCs interface, the optical images of LCs were more stable in the presence of EAN during a month of observation under the condition of unchanging solvent. The photoresponsive ordering transitions of LCs were reversible for many times. Therefore, the IL-LCs interface has better controllability, stability and reproducibility. This work will inspire fundamental studies and novel applications of using the LCs-based imaging technique to investigate various chemical and biological events in ILs.更多还原