超分子模板法合成层状中孔结构氧化铝

利用烷基硫酸钠作为模板剂在室温下合成了层状中孔结构氧化铝,考察了表面活性剂碳链长度和表面活性剂混合比例对层状氧化铝中孔相结构参数的影响.当使用单一表面活性剂作为模板剂时,层状中孔结构氧化铝的层间距d及其层状结构的长程有序度随着表面活性剂碳链长度的增加而增加;若使用C₈H₁₇SO₄Na与C₁₄H₂₉SO₄Na混合表面活性剂作为混合模板剂,当C₁₄H₂₉SO₄Na摩尔分数x处在0～0.5时,层间距基本恒定,接近于具有二者平均碳链长度(n=11)的单一表面活性剂作为模板剂时的情形;当x>0.5时,层间距随x的增大而逐渐增大.通过提出的混合表面活性剂在无机层中的分子排列结构模型对该结果做了解释.

Synthesis of Lamellar Mesostructured Alumina by Supramolecular Templating

Lamellar mesostructured alumina was synthesized at room temperature by using alkyl sulfates as templates. The effects of the length of the surfactant alkyl chain and the ratio of mixed surfactants on the structural data of the obtained lamellar mesophases were investigated. It was revealed that when single surfactants were used as templates, the interlayer spacing(d) as well as the long-range order of the lamellar structure increases with increasing alkyl chain length. When the carbon number(n) of the alkyl chains varies from 8 to 12, the plot of d versus n is linear with a slope of 0.205 nm/carbon atom, which indicates that for n=8～12, the thickness of the inorganic layers keeps nearly constant and the alkyl chains are arranged as double layers between the inorganic layers with a tilt angle of ca. 53. If mixed surfactants C₈H₁₇SO₄Na-C₁₄H₂₉SO₄Na are used as mixed templates, when the molar fraction(x) of C₁₄H₂₉SO₄Na varies in the range of 00.5, the interlayer spacing increases gradually with x. This result has been interpreted in terms of a proposed structure model for the molecular arrangement of mixed surfactants between the inorganic layers.