Preparation and characterization of nanofiber- and nanorod-like boehmite aerogels via ammonia vapor gelation method
Preparation and characterization of nanofiber- and nanorod-like boehmite aerogels via ammonia vapor gelation method
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DOI：
10.1007/s10971-022-05944-4
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发表时间：
2022-09
影响因子：
2.5
通讯作者：
Linyan Wang;Wenjie Li;Tianliang Pang;Han Liu;Chan-Keun Wang;Liang Zhou;Fei He
中科院分区：
文献类型：
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作者：
Linyan Wang;Wenjie Li;Tianliang Pang;Han Liu;Chan-Keun Wang;Liang Zhou;Fei He
以一维薄水铝石纳米纤维和纳米棒为结构单元，壳聚糖为粘结剂，采用溶胶-凝胶法和冷冻干燥法制备了纳米纤维状和纳米棒状薄水铝石气凝胶。采用氨气凝胶法对两种薄水铝石溶胶进行了凝胶化。纳米纤维状建筑单元相互连接和缠绕形成BA-160的高比表面积多孔结构，而纳米棒状建筑单元自我积累和重叠形成大孔径的BA-200骨架。BAS的压缩性能主要来源于建筑单元之间的搭接节点之间的相互作用，纳米纤维之间的搭接节点提供了比纳米棒之间更多的抗压位置。在壳聚糖大分子的帮助下，骨架进一步增强，这是由于改进了铝氧烷通过氨蒸气进行的缩聚。随着壳聚糖含量的增加，BAS的力学性能提高，但导热系数降低。以一维薄水铝石纳米纤维和纳米棒为构筑单元，壳聚糖为粘结剂，采用溶胶-凝胶法和冷冻干燥法制备了纳米纤维状和纳米棒状薄水铝石气凝胶。氨水蒸气诱导薄水铝石溶胶凝胶化，有利于薄水铝石溶胶的均匀凝胶化。由于不同的多孔结构特征，两种砂岩具有不同的力学性能。所有的基础都呈现出超轻和隔热的特点。
Nanofiber-like and nanorod-like boehmite aerogels (BAs) were synthesized by using 1D boehmite nanofibers and nanorods as building units and chitosan as binder via sol-gel process and freeze-drying method. Two kinds of boehmite sols were both gelled via ammonia vapor gelation method. Nanofiber-like building units interconnect and tangle to form high-surface-area porous structures of BA-160, while nanorod-like ones self-accumulate and overlap to construct large-pore-diameter skeletons of BA-200. The compressive property of BAs mainly originates from the interaction of overlap joints between building units, and the overlap joints among nanofibers provide more anti-pressure positions than the ones among nanorods. The skeletons are further enhanced under the help of chitosan macromolecules due to the improved polycondensation between aluminoxane via ammonia vapor. With the increase of chitosan content, the mechanical properties of BAs increase, but the thermal conductivities decrease. All of ultralight BAs can be regarded as good thermal insulation materials.Nanofiber-like and nanorod-like boehmite aerogels (BAs) were synthesized by using 1D boehmite nanofibers and nanorods as building units and chitosan as binder via sol-gel process and freeze-drying method. Boehmite sols turning into gels were induced by ammonia vapor, which is beneficial to homogeneous gelation of boehmite sols. Two kinds of BAs possess different mechanical properties due to different porous structural characteristics. All of BAs present the features of ultralight and thermal insulation.