高岭石-硬脂酸插层复合物的制备及结构模型的提出

Synthesis and Possible Modeling of Kaolinite-Stearic Acid Intercalation Compound

以张家口高岭土为原料,通过直接插层与取代相结合的方法制备高岭石-硬脂酸插层复合物。利用X射线粉末衍射、红外光谱、热重及透射电子显微镜对制备产物进行表征。结果表明：硬脂酸插入到高岭石层间,高岭石层间距d001值由0.72 nm增加到4.05～4.37 nm,插层率达到86.9%;反应时间和溶液p H值会对高岭石-硬脂酸插层复合物的层间距及插层率产生影响;甲氧基嫁接在高岭石表面,与硬脂酸分子同时存在于高岭石层间。高岭石经甲醇改性后脱羟基温度明显降低,高岭石羟基活性提高;高岭石-硬脂酸插层复合物的稳定温度在160℃以下。经过硬脂酸插层改性后的高岭石片层,从边缘开始出现卷曲现象,并且部分长条状片层形成类似埃洛石相的纳米卷;对硬脂酸插层高岭石的作用机理进行分析,结合结构计算,提出高岭石-硬脂酸插层复合物的结构模型,该模型可以解释高岭石-硬脂酸插层复合物在不同条件制备产物层间距变化的原因。

Kaolinite-stearic acid intercalation compound was synthesized via intercalation and displacement using kaolinite from Zhangjiakou as raw material.The new intercalation compounds were characterized by X-ray diffraction（XRD）,Fourier transform infrared spectracopy（FTIR）,Thermal Gravity Analysis（TG/DTG） and Transmission Electron Microscope（TEM）.Experimental results show that the basal spacing of kaolinite-stearic acid intercalation compound is 4.05 ～4.37 nm and the intercalationrate of the product reaches to 86.9%.The intercalation time and the p H value of the solution have influence on the basal spacing and intercalationrate.The methoxy groups which were grafted with iner surface OH groups and the stearic acid molecules are inside the interlayers of the kaolinite.The TG/DTG Analyses were to conform that the activity of kaolinite hydroxyl increased after methanol modified.Some sheets of the kaolinite-stearic acid compound have rolled up from the edge and formed nanoscrolls which is similar with halloysite.The possible intercalation mechanism is analyzed.A model was provided by structural computation in theory.The results show that the reason about the changed spacings of the compounds in different conditions is explained by the model.