Pan Yue, Zhao Chunhua, Wang Ruirui, Zhu Mingjie, Zhuang Wenchang, Li Qintang
School of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, P. R. China.
State Key Laboratory of Offshore Oil and Gas Exploitation, Beijing 100028, P. R. China.
Soft Matter. 2024 Sep 25;20(37):7420-7428. doi: 10.1039/d4sm00699b.
The structure of ionic liquids (ILs) has an influence on their physiochemical properties, determining their performance as self-assembly media. In this study, we focus on the anion effect of aprotic ionic liquids (AILs). The aggregation behaviours of the cationic surfactant 1-hexadecyl-3-methylimidazolium bromide (CmimBr) have been investigated in the imidazolium AILs with the 1-ethyl-3-methyl imidazolium cation and different anions, including nitrate, ethylsulfate, bis(trifluoromethylsulfonyl) imide and tetrafluoroborate. Surface adsorption parameters of CmimBr were determined using surface tension measurements, and the critical micellization concentration values in AILs vary for their different cohesive energy. The micellar and lamellar lyotropic liquid crystal phases emerge with the increase of CmimBr concentrations. The structure and properties of aggregates were determined using small angle X-ray scattering, polarized optical microscopy, rheology and differential scanning calorimetry. The anion effects of AILs on the phase behaviours and structure and properties of aggregates were analysed and discussed. The lamellar lyotropic liquid crystals have shown good conductivity, as confirmed by electrochemical impedance spectroscopy characterization. Our results enhance the understanding of the structure effect of ILs as self-assembly media and contribute to the design of tailorable solvents.
离子液体（ILs）的结构对其物理化学性质有影响，决定了它们作为自组装介质的性能。在本研究中，我们聚焦于非质子离子液体（AILs）的阴离子效应。研究了阳离子表面活性剂1-十六烷基-3-甲基咪唑溴盐（CmimBr）在具有1-乙基-3-甲基咪唑阳离子和不同阴离子（包括硝酸根、硫酸乙酯、双（三氟甲基磺酰）亚胺和四氟硼酸根）的咪唑型AILs中的聚集行为。通过表面张力测量确定了CmimBr的表面吸附参数，并且由于AILs不同的内聚能，其临界胶束浓度值也有所不同。随着CmimBr浓度的增加，出现了胶束和层状溶致液晶相。使用小角X射线散射、偏光显微镜、流变学和差示扫描量热法确定了聚集体的结构和性质。分析并讨论了AILs的阴离子效应对聚集体相行为、结构和性质的影响。通过电化学阻抗谱表征证实，层状溶致液晶具有良好的导电性。我们的结果增进了对ILs作为自组装介质的结构效应的理解，并有助于可定制溶剂的设计。
