合成条件对SiO_2介孔空心微球形貌及结构的影响

以十二胺为主模板剂、聚乙二醇1000为辅助模板剂合成了具有介孔孔壁、比表面积高达951m2/g的空心二氧化硅微球(HSSM).考察了温度、浓度、溶剂等合成条件对HSSM结构及形貌的影响.实验结果表明:合成温度及溶剂对HSSM的结构及形貌影响显著;最佳的水/乙醇体积比为5∶2,此条件下可得到外表光滑、有序度高的空心微球;水/乙醇体积比高于6∶1时,空心微球形貌不规整,有序度也较低;水/乙醇体积比低于4∶3时,得到有序度良好的褶皱状形貌介孔材料;最佳的合成温度约为30～40℃,低于该温度时合成的样品难以形成空心微球结构,而高于该温度时空心微球结构将受到破坏;混合模板剂浓度增加到0.038mol/L及以上时,可以得到空心微球,否则只能得到实心微球.

Effects of Synthesis Conditions on Morphology and Structure of Hollow Mesoporous Silica Microspheres

Hollow silica spheres material(HSSM) with mesoporous wall and a specific surface area up to 951m~2/g were successfully synthesized, with dodecyl amine as the main template and with polyethylene glycol 1000 as the co-template. The effects of such synthesis conditions as temperature, concentration and solvent on the structure and morphology of HSSM were then investigated. The results show that (1) both the temperature and the solvent obviou-sly influence the morphology and structure of HSSM;(2) at the optimal volume ratio of water to ethanol, namely 5:2, hollow microspheres with smooth surface and high structure-ordering degree can be obtained;(3) a volume ratio higher than 6:1 or lower than 4:3 may result in irregular bulk with low ordering degree or mesoporous material with high ordering degree, respectively;(4) when the synthesis temperature is lower than the optimal one, namely 30 to 40℃, hollow microspheres cannot be obtained, while hollow microspheres may be destroyed when the temperature is higher than the optimal one;and (5) only when the mixed template concentration increases to 0.038mol/L can hollow microspheres-but not solid microspheres-be synthesized.