Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia.
Langmuir. 2010 Dec 21;26(24):19073-83. doi: 10.1021/la1030763. Epub 2010 Nov 19.
The high-temperature morphology of supported liquid membranes (SLMs) prepared from perfluorinated membranes such as Nafion and Hyflon and hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-TFSI) has been investigated by small-angle X-ray scattering (SAXS). Proton conductivity results of SLMs before and after leaching show an increase in conductivity with temperature up to 160 °C in an anhydrous environment. DSC results show that crystallites within perfluorinated membranes are thermally stable up to 196 °C. High-temperature SAXS results have been used to correlate structure and morphology of supported liquid membranes with high-temperature conductivity data. The ionic liquid essentially acts as a proton solvent in a similar way to water in hydrated Nafion membranes and increases size of clusters, which allow percolation to be achieved more easily. The cation of the ionic liquid interacts with sulfonate groups within ionic domains through electrostatic interactions and displaces protons. Protons can associate with free anions of the ionic liquid, which are loosely associated with cations and can transport by hopping from anion sites within the membrane. The ionic liquid contributes to proton conductivity at high temperature through achievement of long-range ordering and subsequent percolation.
采用小角 X 射线散射（SAXS）研究了全氟膜（如 Nafion 和 Hyflon）和疏水性离子液体 1-丁基-3-甲基咪唑双（三氟甲基磺酰基）亚胺（BMI-TFSI）制备的支撑液膜（SLM）的高温形态。在无水环境中，SLM 浸出前后的质子传导率结果表明，在 160°C 以下，随着温度的升高，电导率升高。DSC 结果表明，全氟膜内的晶体在 196°C 以下热稳定。高温 SAXS 结果用于将支撑液膜的结构和形态与高温电导率数据相关联。离子液体在类似于水合 Nafion 膜中水分子的作用下充当质子溶剂，并增加了簇的大小，从而更容易实现渗流。离子液体的阳离子通过静电相互作用与离子域内的磺酸盐基团相互作用并置换质子。质子可以与离子液体的游离阴离子结合，后者与阳离子松散结合，并可以通过在膜内从阴离子位跳跃来传输。离子液体通过实现长程有序和随后的渗流，对高温下的质子传导率做出贡献。
