模板剂去除方法对介孔氧化硅纳米球的影响

Influence of Template Removal Methods on Mesoporous Silica Nanospheres

以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸四乙酯(TEOS)为硅源,在碱性条件下反应,分别采用煅烧法和酸化乙醇回流萃取法去除氧化硅中的模板剂,获得了直径为100nm分布均匀的六方有序的介孔氧化硅纳米球(MSN)。通过热失重分析(TGA)、透射电子显微镜(TEM)、小角度X射线衍射(SAXRD)和氮气吸附-脱附对MSN中CTAB的残余量和介孔结构进行了表征。结果表明:煅烧法能够彻底去除模板剂,萃取法只能去除80%左右的模板剂;随着萃取时间的延长和萃取次数的增加,MSN的孔径和孔容有所增加,其中6h回流萃取4次去除模板剂后得到的MSN的比表面积、孔容、孔径最大,分别为944.31m2.g-1、1.89cm3.g-1和2.56nm。

Hexagonal ordered mesoporous silica nanospheres（MSN） with a diameter of 100 nm were obtained by using tetraethoxysilane（TEOS） as silica source and cetyltrimethylammonium bromide（CTAB） as the template under alkaline conditions of 2 M sodium hydroxide.The CTAB templates were removed by calcination at 550℃ and by reflux extraction using HCl/EtOH solution,respectively.Thermogravimetric analysis（TGA）,small angle X-ray diffractometry（SAXRD）,transmission electron microscopy（TEM） and nitrogen adsorption-desorption techniques were employed to investigate the residue of CTAB and mesoporous structure of MSN.The results indicate that templates can be removed completely by calcination but only about 80% templates can be removed by reflux extraction.The pore size and pore volume of MSN increase with increasing the extraction time and repeated times of extraction.MSN obtained by extraction for 6 h with 4 repeated times to remove templates has the largest surface area（944.31m2·g-1）,pore volume（1.89cm3·g-1） and pore diameter（2.56nm）.