Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites
Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites
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DOI：
10.1016/s0040-6031(03)00334-4
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发表时间：
2004-01-09
影响因子：
3.5
通讯作者：
Fox, DM
中科院分区：
文献类型：
--
作者：
Awad, WH;Gilman, JW;Fox, DM
提高有机改性的层状硅酸盐的热稳定性是聚合物-层状硅酸盐纳米复合材料在工业规模上成功技术应用的关键点之一。为了克服烷基铵处理蒙脱土热稳定性差的不利影响，制备了一系列烷基咪唑熔融盐，并通过元素分析、热重分析（TGA）和热脱附质谱（TDMS）对其进行了表征。考察了抗衡离子、烷基链长和结构异构性对咪唑盐热稳定性的影响。通过咪唑盐与钠基蒙脱土的离子交换制备了烷基咪唑盐改性蒙脱土。采用X射线衍射（XRD）、热重-傅里叶变换红外光谱（TGA-FTIR）、差热分析（TDMS）等方法对改性粘土进行了表征，并与常规的季铵型蒙脱土进行了比较。结果表明，反离子对咪唑盐的热稳定性有影响，含PF 6-、N（SO2 CF 3）（2）（-）和BF 4-的咪唑盐比含卤离子的咪唑盐热稳定性好。烷基的链长与热氧化稳定性之间存在一定的关系，从丙基、丁基、癸基、十六烷基、十八烷基到二十烷基，随着链长的增加，热氧化稳定性降低。结果还表明，与咪唑鎓卤化物相比，咪唑鎓处理的蒙脱土具有更高的热稳定性。通过FTIR分析分解产物提供了关于分解产物是水、二氧化碳和烃的洞察。(C)2003 Elsevier B. V.保留所有权利。
Increasing the thermal stability of organically-modified layered silicates is one of the key points in the successful technical application of polymer-layered silicate nanocomposites on the industrial scale. To circumvent the detrimental effect of the lower thermal stability of alkyl ammonium-treated montmorillonite, a series of alkyl-imidazolium molten salts were prepared and characterized by elemental analysis, thermogravimetry (TGA) and thermal desorption mass spectroscopy (TDMS). The effect of counter ion, alkyl chain length and structural isomerism on the thermal stability of the imidazolium salts was investigated. Alkyl-imidazolium-treated montmorillonite clays were prepared by ion exchange of the imidazolium salts with Na-montmorillonite. These organically-modified clays were characterized by X-ray diffraction (XRD), TDMS and thermogravimetry coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and compared to the conventional quaternary alkyl ammonium montmorillonite. Results indicate that the counter ion has an effect on the thermal stability of the imidazolium salts, and that imidazolium salts with PF6-, N(SO2CF3)(2)(-) and BF4- anions are thermally more stable than the halide salts. A relationship was observed between the chain length of the alkyl group and the thermo-oxidative stability; as the chain length increased from propyl, butyl, decyl, hexadecyl, octadecyl to eicosyl, the stability decreased. The results also show that the imidazolium-treated montmorillonite has greater thermal stability compared to the imidazolium halide. Analysis of the decomposition products by FTIR provides an insight about the decomposition products which are water, carbon dioxide and hydrocarbons. (C) 2003 Elsevier B.V. All rights reserved.