Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR
Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR
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DOI：
10.1016/j.jcis.2004.12.048
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发表时间：
2005-06-01
影响因子：
9.9
通讯作者：
Deng, F
中科院分区：
文献类型：
--
作者：
Zhu, JX;He, HP;Deng, F
用傅里叶变换红外光谱(FTIR)和高分辨率单脉冲C-13魔角旋转核磁共振(C-13 SP-MAS)谱研究了插层表面活性剂溴化十六烷基三甲基铵(CTMAB)的分子构象和迁移率。烷基链的构象和迁移率是表面活性剂浓度的函数。FTIR中1473~1463 cm(-1)处的亚甲基剪切峰和730~720 cm~(-1)处的摇摆峰的分裂被认为是插层表面活性剂在粘土孔道内堆积密度增加的诊断。与体相CTMAB的~(13)Sp-MAS核磁共振谱相比，插层表面活性剂分子端甲基(C-16)和亚甲基(C-15，C2-14)的端甲基(C-16)和亚甲基(C-15，C2-14)的化学位移为1-3ppm，表明其构象更自由。对于这些杂化材料，其构象自由度随表面活性剂浓度的增加而减小。此外，在表面活性剂含量较高的杂化材料中，C-1碳原子的场下移量类似于2ppm，表明了一个特殊的局部环境。本研究证明了插层烷基链中碳原子的不同迁移率。(C)2005 Elsevier Inc.保留所有权利。
The molecular conformation and mobility of the intercalated surfactant molecules cetyltrimethylammonium bromide (CTMAB) have been studied using Fourier transform infrared spectroscopy (FTIR) and high-resolution single-pulse C-13 magic angle spinning nuclear magnetic resonance (C-13 SP MAS NMR) spectroscopy. The conformation and mobility of alkyl chains were found to be a function of the surfactant concentration. The splitting of the methylene scissoring mode at 1473-1463 cm(-1) and the rocking mode at 730-720 cm-1 in FTIR are considered to be diagnostic of the packing density increase of the intercalated surfactants within the clay gallery. Compared with the C-13 Sp MAS NMR spectrum of CTMAB in the bulk state, 1-3 ppm upfield chemical shifts for end-methyl (delta C-16) and methylene (delta C-15, delta C2-14) of the intercalated surfactant molecules in the hybrids indicate a freer conformational situation. For these hybrids, the conformational freedom decreases with increased of surfactant concentration. In addition, on similar to 2 ppm downfield shift for the C-1 carbon atom in the hybrids with higher surfactant content suggests a special local environment. This study demonstrates the different mobility of carbon atoms in the intercalated alkyl chain. (c) 2005 Elsevier Inc. All rights reserved.