离子凝胶的结构洞察:以限制在气相二氧化硅中的1-甲基-3-辛基咪唑四氟硼酸盐为例的研究。

Structural Insight into Ionogels: A Case Study of 1-Methyl-3-octyl-imidazolium Tetrafluoroborate Confined in Aerosil.

作者信息

Kottsov Sergei Yu, Kopitsa Gennady P, Baranchikov Alexander E, Pavlova Alina A, Khamova Tamara V, Badulina Alexandra O, Gorshkova Yulia E, Selivanov Nikita A, Simonenko Nikolay P, Nikiforova Marina E, Ivanov Vladimir K

机构信息

Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Leninsky Prospekt, 31, 119991 Moscow, Russia.

Petersburg Nuclear Physics Institute NRC KI, Orlova rosha 1, 188300 Gatchina, Leningrad District, Russia.

出版信息

Langmuir. 2024 Nov 12;40(45):23962-23972. doi: 10.1021/acs.langmuir.4c03162. Epub 2024 Oct 30.

Abstract

Ionogels were obtained by impregnating Aerosil A380 with 1-methyl-3-octyl-imidazolium tetrafluoroborate (OMIM BF) ionic liquid (IL). The IL content of the ionogels varied from 16.3 to 79.9 mol %. There was evidence of the confinement of the IL in silica in the shift and broadening of the BF F NMR signal and in the noticeable (∼50 °C) decrease in the temperature of IL decomposition. For both the ionogels and the pure IL, the frequencies of IR vibrations were different, providing further evidence of the confinement effect. An analysis of textural characteristics revealed that, upon its addition to Aerosil, the IL sequentially adsorbed in the micropores, mesopores and interparticle space. SAXS measurements showed that, in the confined IL, the size of nonpolar correlations substantially increased, from 21.5 Å in the bare IL to 25.6 Å in the ionogel containing 28.1 mol % IL. Unexpectedly, for the ionogel with the lowest IL content (16.3 mol %), no nonpolar correlations were observed, indicating the strong distortion of the structure of the confined ionic liquid. To the best of the authors' knowledge, this is the first report on regular changes in nonpolar correlations in ionic liquids upon confinement in a porous solid. These structural correlations can easily be tuned by simply changing the IL content in the ionogel material.

摘要

通过用1-甲基-3-辛基咪唑四氟硼酸盐(OMIM BF)离子液体(IL)浸渍Aerosil A380来制备离子凝胶。离子凝胶中IL的含量在16.3至79.9摩尔%之间变化。在BF F NMR信号的位移和展宽以及IL分解温度明显降低(约50°C)方面,有证据表明IL被限制在二氧化硅中。对于离子凝胶和纯IL,红外振动频率都不同,这进一步证明了限制效应。对结构特征的分析表明,将IL添加到Aerosil中后,它依次吸附在微孔、中孔和颗粒间空间中。小角X射线散射(SAXS)测量表明,在受限的IL中,非极性关联的尺寸大幅增加,从纯IL中的21.5 Å增加到含28.1 mol%IL的离子凝胶中的25.6 Å。出乎意料的是,对于IL含量最低(16.3 mol%)的离子凝胶,未观察到非极性关联,这表明受限离子液体的结构发生了强烈扭曲。据作者所知,这是关于离子液体在多孔固体中受限后非极性关联发生规律性变化的首次报道。通过简单改变离子凝胶材料中的IL含量,这些结构关联很容易被调节。

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