介孔二氧化硅的形貌控制：螺旋纳米纤维，纳米介孔球和多级结构空心球

MORPHOLOGICAL CONTROL OF MESO-STRUCTURED SILICA： HELICAL NANOFIBERS, NANOSPHERES AND HIERARCHICAL HOLLOW SPHERES

报道了不同形貌（包括螺旋纳米纤维、纳米球和多级结构空心球）的介孔二氧化硅的合成和表征。以阳离子表面活性剂十六烷基三甲级溴化铵为模板，在两相体系中合成了螺旋纳米介孔纤维。这类螺旋纳米纤维中的六方排列介孔孔道围绕纤维轴向呈螺旋状盘绕，同时，纤维整体也可进一步盘绕出更高一级的螺旋结构。以N-酰基氨基酸阴离子表面活性剂为模板，合成了具有中-D辐射孔道结构的单分散二氧化硅纳米球，球的尺度可以通过合成体系的酸度调节。还以一种简单的乳液模板方法合成了同时具有蠕虫介孔球壳和层状结构芽式结构的空心球，并讨论其形成机理。

In this work, the synthesis and characterizations of meso-structured silica with different morphologies are reported, including helical nanofibers, nanospheres and hierarchical hollow spheres. The helical mesoporous silica nanofibers are organized by using the template of cationic surfactant cetyltrimethylammonium bromide （CTAB） in a two-phase system. These helical nanofibers possess rope-like twisted hexagonal morphology and helical mesoporous channels running inside winding around the fiber axis. These twisted hexagonal nanofibers can further curve spirally to form a second-level helical morphology （hierarchically helical morphology）. Monodispersed silica nano-spheres have been synthesized by using anionic N-acyl amino acid surfactant as template. The sizes of the spheres are uniform and can be finely tuned by changing pH value. The mesopores in the sphere exhibit radial symmetry starting from the center part to the spherical surface, observed by TEM images. As the pH value decreases, rod-like mesoporous silica with core-shell structure can be discovered. The ordered mesporous core can be formed gradually by realignment of the pore channels as the particle continues to grow. Hierarchical morphology of budded mesoporous silica hollow spheres, which contain wormhole-like mesoporous shell with protruding lamellar （vesicular） meso-structured buds, has been fabricated by a single step emulsion-templating method. This unique self-assembly leads to spontaneous formation of two distinct domains of different lyotropic liquid crystal mesophases on one hollow sphere.