Morphology maps of ice-templated silica gels derived from silica hydrogels and hydrosols
Morphology maps of ice-templated silica gels derived from silica hydrogels and hydrosols
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DOI：
10.1016/j.micromeso.2008.03.031
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发表时间：
2008-12
影响因子：
5.2
通讯作者：
S. Mukai;H. Nishihara;H. Tamon
中科院分区：
文献类型：
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作者：
S. Mukai;H. Nishihara;H. Tamon
通过对水玻璃水溶液合成的硅水凝胶和硅水溶胶进行单向冷冻，制备了不同形状的冰模板硅胶。研究了前驱体（水凝胶和水溶胶）的性质与产物形状之间的关系。决定凝胶形状的主要因素是二氧化硅的迁移率。从水凝胶中，获得了具有直通道的多孔单体（微蜂窝），具有多边形横截面的纤维和粉末。另一方面，从水溶胶、薄片、扁平纤维和微型蜂窝中获得。对于水溶胶和水凝胶，我们试图建立形态学图，使我们能够从前体的可调参数中轻松预测最终形状。在水凝胶的情况下，根据凝胶和冻结之间的经过时间以及水凝胶的凝胶时间，可以将地图划分为对应每种形状的单个区域。另一方面，在水溶胶的情况下，根据水溶胶在冻结时的松弛时间和水溶胶的凝胶时间，可以将地图划分为与每种形状对应的单个区域。
Ice-templated silica gels with various shapes were prepared through the unidirectional freezing of silica hydrogels and silica hydrosols that were synthesized from aqueous sodium silicate solutions. The relationship between the characteristics of the precursors (hydrogels and hydrosols) and the resulting shape was investigated. The dominant factor which governs the shape of the resulting gel was found to be the mobility of silica. From hydrogels, porous monoliths with straight channels (microhoneycombs), fibers with polygonal cross-sections, and powders were obtained. On the other hand, from hydrosols, lamellas, flat fibers, and microhoneycombs were obtained. For both hydrosols and hydrogels, we attempted to establish morphology maps which allow us to easily predict the resulting shape from the adjustable parameters of the precursors. In the case of hydrogels, the map could be divided into individual regions which correspond to each type of shape according to the elapsed time between gelation and freezing, and the gelation time of the hydrogel. On the other hand, in the case of hydrosols, the map could be divided into individual regions which correspond to each type of shape according to the relaxation time of the hydrosol at the time of freezing and the gelation time of the hydrosol.