Influence of the cation alkyl chain length of imidazolium-based room temperature ionic liquids on the dispersibility of TiO2 nanopowders
Influence of the cation alkyl chain length of imidazolium-based room temperature ionic liquids on the dispersibility of TiO2 nanopowders
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DOI：
10.1007/s11051-013-1463-2
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发表时间：
2013-02
影响因子：
2.5
通讯作者：
A. Wittmar;Martyna Gajda;D. Gautam;U. Dörfler;M. Winterer;M. Ulbricht
中科院分区：
文献类型：
--
作者：
A. Wittmar;Martyna Gajda;D. Gautam;U. Dörfler;M. Winterer;M. Ulbricht
采用动态光散射和高级流变学方法，首次研究了阳离子烷基链长对超声处理纳米二氧化钛在亲水性咪唑基室温离子液体中分散性的影响。采用化学气相合成法(CVS)在不同条件下制备了两种不同的二氧化钛纳米粉末。一种商用纳米粉末被用于比较。用透射电子显微镜、X-射线衍射仪、氮气吸附比表面积分析和傅里叶变换红外光谱等手段对其进行了表征。对于基于CVS的材料，主要颗粒尺寸约为6纳米和8纳米，对于商业材料，一次颗粒尺寸约为26纳米。对于所有不同结构特征和分散体中浓度的所研究的粉末，阳离子烷基链的长度对分散体中的粒度分布有很大的影响。结果表明，随着烷基链长的增加，分散体系的粒径分布变窄，团聚尺寸减小。分散体中最小的平均纳米颗粒尺寸约为30 nm。此外，纳米粒子的表面官能度、固体物质在液体中的浓度以及超声处理的时间控制着分散质量，特别是在烷基链较短的离子液体的情况下。随着阳离子烷基链长的增加，纳米粉末的性质对其分散性的影响明显减小。结果表明，具有合适结构的离子液体可作为气相合成纳米粒子的吸收介质，直接获得液体分散体，而不需要再分散。
The influence of the length of the cation alkyl chain on the dispersibility by ultrasonic treatment of TiO2nanopowders in hydrophilic imidazolium-based room temperature ionic liquids was studied for the first time by dynamic light scattering and advanced rheology. TiO2nanopowders had been synthesized by chemical vapor synthesis (CVS) under varied conditions leading to two different materials. A commercial nanopowder had been used for comparison. Characterizations had been done using transmission electron microscopy, X-ray diffraction, nitrogen adsorption with BET analysis, and FT-IR spectroscopy. Primary particle sizes were about 6 and 8 nm for the CVS-based and 26 nm for the commercial materials. The particle size distribution in the dispersion was strongly influenced by the length of the cation alkyl chain for all the investigated powders with different structural characteristics and concentrations in the dispersion. It was found that an increase of the alkyl chain length was beneficial, leading to a narrowing of the particle size distribution and a decrease of the agglomerate size in dispersion. The smallest average nanoparticle sizes in dispersion were around 30 nm. Additionally, the surface functionality of the nanoparticles, the concentration of the solid material in the liquid, and the period of ultrasonic treatment control the dispersion quality, especially in the case of the ionic liquids with the shorter alkyl chain. The influence of the nanopowders characteristics on their dispersibility decreases considerably with increasing cation alkyl chain length. The results indicate that ionic liquids with adapted structure are candidates as absorber media for nanoparticles synthesized in gas phase processes to obtain liquid dispersions directly without redispergation.