长链烷基季铵盐插层氧化石墨的结构变化

基于改进的Hummers法制备氧化石墨(GO),并以长链烷基季铵盐(C_nTAB)对其进行插层处理;通过改变C_nTAB的链长、浓度,得到系列C_nTAB/GO插层复合物。采用XRD和元素分析对产物的最大底面间距及C_nTAB插入量进行表征。结果表明,随着C_nTAB链长的增长、C_nTAB浓度的增大,C_nTAB/GO插层复合物的最大底面间距逐渐增大。C_nTAB通过离子键作用和疏水键作用插入到GO层间,在GO片层上的吸附规律符合修正型(Modified)Langmuir模型,即C_nTAB以单分子层吸附在GO片层上。根据C_nTAB/GO插层复合物最大底面间距及C_nTAB插入量的变化规律分析,得出C_nTAB在GO层间的排布模式有单层平躺模式、类双层平躺模式、单层倾斜模式和单层直立模式。

Structure Change of Quaternary Alkylammonium Graphite Oxide Intercalation Composite

The graphite oxide (GO) samples were prepared from flake graphite via modified Hummers method. A series of quaternary alkylammoniumgraphite oxide intercalation composites (C_nTAB/GO) were synthesized by changing the alkyl chain length and surfactant concentration, respectively. The structure and intercalated amount of C_nTAB for intercalation composites were characterized by using XRD and elemental analysis. The results suggest that the interlayer spacing of C_nTAB/GO composites increases with the increase of alkyl chain length or surfactant concentration. It is also found that the experimental data obtained from surfactants in GO spacing have been fitted well into the Modified Langmuir adsorption isotherm equations,indicating that the C_nTAB molecules are adsorbed on the surface of GO within a monomolecular layer. The result of elemental analysis also suggests that surfactant is intercalated into GO spacing via electrovalent and hydrophobic interaction. Finally, the arrangement models of the surfactant in the layer of GO include lateral monolayer, lateral bilayer, paraffin-type monolayer and vertical monolayer.