Aerogel fibers, the simultaneous embodiment of aerogel 3D network and fibrous geometry, have shown great advantages over natural and synthetic fibers in thermal insulation. However, as a fast gelation to ensure aerogel fiber spinning generally induces rapid local clustering of precursor particles (i.e., phase separation) and unavoidably results in nontransparency and nonuniformity in the gel state, a severe challenge remains in remedying the spinning to make transparent aerogel fibers come true. Herein, we report a reaction spinning toward highly porous silica aerogel fibers, where the Brownian motion (i.e., diffusion) of colloidal particles is hampered during spinning to allow the maintaining of the fiber shape, while a rapid gelation reaction is activated by concentrated ammonia to solidify the fiber. The aggregation degree of the primary particles can be precisely controlled by pH-dependent hydrolyzation, and thus, the final aerogel fiber can be either transparent or opaque, as dominated by Rayleigh or Mie scattering. The resulting transparent silica aerogel fibers with low density, high specific surface area, and flexibility can inherit advanced features including excellent thermal insulation, wide temperature stability, and optional hydrophobic functionalization and, thus, be suitable for wearable applications.

中文翻译：

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反应纺透明二氧化硅气凝胶纤维。

气凝胶纤维是气凝胶3D网络和纤维几何形状的同时体现，在隔热方面已显示出优于天然纤维和合成纤维的巨大优势。然而，由于确保气凝胶纤维纺丝的快速凝胶化通常会引起前体颗粒的快速局部聚集（即相分离），并且不可避免地导致凝胶状态不透明和不均匀，因此在补救纺丝以制备透明气凝胶纤维方面仍然存在严峻的挑战成真。在此，我们报告了一种反应朝着高度多孔的二氧化硅气凝胶纤维旋转，其中布朗运动（即胶体颗粒在纺丝过程中受到阻碍（扩散），以保持纤维形状，同时浓氨水激活了快速的胶凝反应以固化纤维。初级颗粒的聚集度可以通过pH依赖的水解来精确控制，因此，最终的气凝胶纤维可以是透明的或不透明的，以瑞利散射或米氏散射为主导。所得的具有低密度，高比表面积和柔韧性的透明二氧化硅气凝胶纤维可以继承先进的功能，包括出色的隔热性，宽广的温度稳定性和可选的疏水功能化，因此适合穿戴式应用。