FTIR和XRD研究甲酰胺在高岭石插层复合体系中的形态及其复合物的微观结构

插层复合体系中，有机插层剂在插层的同时也可能吸附在复合物的表面或以自由态存在，对插层分子的表征将会产生较大的影响。以丙酮作淋洗剂，用FTIR及XRD技术对淋洗前后的插层复合体系监控，插层剂分子在复合体系中的可能存在形式，探讨水的作用及复合物微观结构的变化。结果显示：甲酰胺有插层、游离和吸附在复合物表面三种存在形态。3 355和3 462 cm-1处的红外振动峰归属于表面吸附的插层剂分子，3 626 cm-1的峰归属于插层的H₂O分子，在干燥后均消失。H₂O作为填充空间的分子参预了插层过程，且插入到层间，并在干燥后脱嵌。3 534 cm-1处的振动峰在淋洗前后一直存在，是由于插层的甲酰胺分子与高岭石层间形成氢键作用的结果。以丙酮作为淋洗剂，可以选择性的消除表面吸附的甲酰胺而不影响复合物的结构。插层的甲酰胺分子以C—N键垂直于层片呈单分子层排列，并通过氨基与高岭石铝氧八面体层的内表面羟基和硅氧四面体层的氧形成了两种氢键作用。

Study on the Occurrence Status of Formamide in Kaolinite-Formamide Intercalation System and the Microstructure of Its Compounds by FTIR and XRD

The objectives of this study are to investigate the possible occurrence status of formamide in the intercalation system, the founction of water and the molecular configurations and orientations of formamide inserted into the interlayer of kaolinite, by washing the products with acetone to eliminate the interferences due to the outersurface absorbed formamide molecules in FTIR spectrometry. The results show that the intercalated, absorbed and free formamide probably exist in the intercalation system. Free formamide is easily to be eliminated selectively by drying, whereas the absorbed formamide is removed only by washing with the proper eluting reagent. H₂O also is inserted into the interlayer during the formamide molecules’ intercalation, which is deintercalated after the compounds being dried. Intercalation caused blue shifts of the inner surface OH stretching bands from 3 687 to 3 692 cm-1, and deforming bands from 911 to 906 cm-1 , the bands at 3 651 cm-1 disappeared with a new band appearing at 3 539 cm-1. The frequency of the Si—O bands of kaolinite was slightly shifted. These IR bands changes implied the breaking of the H-bonds between layers of kaolinite, and the formation of new H-bonds between the kaolinite and the inserting formamide molecules in the intercalation compounds. The formamide molecules intercalated were oriented with the C—N bond perpendicular or nearly perpendicular to the (001) surface of the kaolininte and formed 2 types of H-bonding with inner-surface hydroxyls and siloxane layer of the kaolinite respectively through NH₂. A novel model was provided to analyse the microstructure of kaolinite-formamide intercalation compounds. The results show that computation data is in good agreement with experimental data.