Nanohybrid materials from the intercalation of imidazolium ionic liquids in kaolinite
作者:Sadok Letaief、Christian Detellier
DOI:10.1039/b616922h
日期:——
A series of novel organic–inorganic nanohybrid materials were obtained by the intercalation in the interlamellar spaces of the clay mineral kaolinite, of ionic liquids based on imidazolium derivatives. The intercalation procedure was successfully accomplished via a melt reaction strategy using the dimethylsulfoxide–kaolinite intercalate (DMSO-K) as a precursor. 13C MAS NMR as well as XRD, TGA/DTA and FTIR studies confirmed the complete displacement of DMSO molecules by the imidazolium salts during the intercalation process. Increase of the basal spacing from 1.1 nm in DMSO-K to 1.3–1.7 nm in the nanohybrid materials was observed, indicating that imidazolium derivatives are oriented in a way such that the imidazole ring is parallel, or slightly tilted by an angle of 10–25°, with respect to the kaolinite internal surfaces. The number of moles of organic material loaded in the nanohybrids was obtained from several independent measurements. The intercalation of the imidazolium salts increases the thermal stability of the resulting material by more than 150 °C with respect to DMSO-K. After heating under air at 300 °C for two hours, XRD showed that the structure of the intercalates was kept with only a slight decrease of the intercalation ratio. The original kaolinite structure was recovered after heating the intercalate at 350 °C for an additional two hours. This observed high thermal stability is promising for the use of these nanohybrid materials as precursor for the synthesis of new nanocomposites by incorporation of polymer in kaolinite at high temperature.
通过在粘土矿物高岭石的层间空间插入基于咪唑盐衍生物的离子液体,获得了一系列新型有机-无机纳米杂化材料。插入过程通过使用二甲基亚砜-高岭石插入物(DMSO-K)作为前驱体的熔融反应策略成功实现。13C魔角旋转核磁共振(MAS NMR)以及X射线衍射(XRD)、热重/差热分析(TGA/DTA)和傅里叶变换红外光谱(FTIR)研究表明,在插入过程中,咪唑盐完全取代了DMSO分子。观察到基面间距从DMSO-K中的1.1 nm增加到纳米杂化材料中的1.3-1.7 nm,表明咪唑盐衍生物以一种方式排列,使得咪唑环与高岭石内部表面平行,或稍微倾斜10-25°。通过几种独立测量方法得到了负载在纳米杂化材料中的有机物摩尔数。咪唑盐的插入使得所得材料的热稳定性相对于DMSO-K提高了150 °C以上。在300 °C下加热两小时后,XRD显示插入物的结构得以保持,仅插入比例略有下降。将插入物在350 °C下再加热两小时后,恢复了原始的高岭石结构。观察到的高热稳定性预示着这些纳米杂化材料作为高温下在高岭石中加入聚合物合成新纳米复合材料前驱体的前景。