Gemini表面活性剂联接基团对合成硅基介孔材料结构的影响

The Influences of the Spacer of Gemini Surfactants on the Structure of Silicic Mesoporous Materials

考察了Gemini表面活性剂不同联接基团对介孔结构的影响,通过改变联接基团碳链的长度和在联接基团中加入苯基和羟基改变链的柔性和亲水性,可改变表面活性剂在两相界面的头基面积和电荷分布,形成不同的表面活性剂溶液结构,并通过自组装过程控制生成不同介孔材料的孔结构.当联接基团链长为4￣8个碳时,得到六方相孔道结构,而当碳链长度增加为10￣12个碳时,形成立方相孔道结构,其中以GEM16-6-16为模板,形成了高度有序的MCM-41,以GEM16-12-16为模板,则得到高度有序的MCM-48.GEM16-3(OH)-16可合成出层状结构,但有序性较低.GEM16-(1-Ar-1)-16的cmc较低,在水溶液中溶解度极低,当加入共溶剂乙醇时,得到了空心球结构.

Gemini surfactants, with two quaternary ammonium head groups separated by a spacer with variable configurations and with each head group attached to a same or different hydrophobic tail, can be used to control the packing parameter and the organic polycharge centers. By this means, the structure of mesoporous material prepared using surfactant template can be considerably controlled by changing the structures of Gemini surfactafit, especially the characteristics of the spacer. The flexibility and the hydrophilicity of the spacer can be changed by varying the length of methylene chain of spacers from 3C to 12C, or adopting phenyl and hydroxyl radicals. These deduced successful synthesis of series of ordered mesoporous structure. When the length of methylene spacer chain of template was between 4C-8C, hexagonal mesoporous materials were produced, while cubic mesoporous materials were obtained when the length of spacer chain was 10C-12C. It is shown that the GEM16-6-16 and GEM16-12-16 were effective templates for highly ordered MCM-41 and MCM-48 respectively. The GEM16-3（OH）-16, which introduced a hydrophilic flexible hydroxyl radical to the spacer, produced less ordered sandwich structure. The GEM16-（1-Ar-1）-16, with a hydrophobic rigid spacer of p-xylyl, was hard to dissolved in water. When ethanol was used as cosolvent, hollow sphere materials were produced. The samples were characterized by XRD, TEM, and N2 adsorption-desorpotion.