Facile fabrication of ultralow-density transparent boehmite nanofiber cryogel beads and their application to a nanoglue
Facile fabrication of ultralow-density transparent boehmite nanofiber cryogel beads and their application to a nanoglue
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DOI：
10.1002/cnma.201600360
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
G. Hayase
中科院分区：
文献类型：
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作者：
G. Hayase
只有通过超临界干燥才能获得密度为5mg cm−3或更低的超低密度透明多孔体材料。在这项工作中，报告了一种简单的方法来获得直径为几毫米的超低密度透明多孔珠。在该方法中，将薄水铝石纳米纤维分散体（BNF溶胶）直接滴入液氮中，然后将微珠真空干燥。通常，通过冷冻干燥获得的多孔材料由于结构不均匀而表现出强烈的光散射，并且不透明。然而，使用稀BNF作为骨架结构抑制了分散介质结晶过程中由于聚集引起的不均匀性。低温凝胶的最低容重为1.1 mg cm−3，可见光透过率达到90%。在冻结前将功能材料分散到BNF溶胶中，得到复合材料。这种简便的方法有望开拓功能多孔材料领域。
Ultralow-density transparent porous bulk materials with densities of 5 mg cm−3 or less have only been obtained by supercritical drying. In this work, a simple method is reported for obtaining ultralow-density transparent porous beads with a diameter of several millimeters. In the method, a boehmite nanofiber dispersion (BNF sol) is dripped directly into liquid nitrogen and the beads are vacuum-dried. Normally, porous materials obtained via freeze drying exhibit strong light scattering due to structural nonuniformity and are not transparent. However, using dilute BNF as a skeleton structure suppressed the inhomogeneity due to aggregation during the dispersion medium crystallization. The lowest bulk density of the cryogel was 1.1 mg cm−3, and the visible light transmittance reached 90 %. By dispersing functional materials into the BNF sol before freezing, composite materials were obtained. The facile method can be expected to develop the field of functional porous materials.