Silica aerogels with tailored chemical functionality
Silica aerogels with tailored chemical functionality
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具有定制化学功能的二氧化硅气凝胶
DOI：
10.1016/j.matdes.2020.108833
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发表时间：
2020-08-01
影响因子：
8.4
通讯作者：
Malfait, Wim J.
中科院分区：
文献类型：
--
作者：
Li, Zhi;Zhao, Shanyu;Malfait, Wim J.
二氧化硅气凝胶是具有非常高的表面积（~ 800 m2/g）的高度多孔（~ 95%）、主要是中孔（20-50 nm）的材料，但是使与高表面积相关的化学性质稳定化的应用落后于使孔结构稳定化的应用（绝热）。在这里，我们提出了广泛适用的协议，以合成和表征有机官能化的二氧化硅气凝胶，具有高表面积（356-1177 m2/g）和高质量负载的表面官能团（1.0-4.9 mmol/g，0.9-3.9 molecules/nm（2））。将湿硅胶浸泡在含有预水解的有机官能三烷氧基硅烷的稀溶液中，然后进行超临界CO2干燥。在干气凝胶中的各种官能团的保留通过FTIR确认，并且通过固态NMR光谱定量它们的浓度。温和的反应条件与所有测试的官能团（硅烷醇、乙氧基、三甲基甲硅烷基、氨基、乙烯基、甲基丙烯酸甲酯、环氧基、膦酸酯）相容，而不需要针对每种特定的官能硅烷进行优化，使得有机官能化气凝胶的合成成为常规任务。(C)2020年，任作家。出版社：Elsevier Ltd
Silica aerogels are highly porous (-95%), predominantly mesoporous (20-50 nm) materials with very high sur face area (-800 m(2)/g), but applications that valorize the chemical properties linked to the high surface area lag behind those that valorize the pore structure (thermal insulation). Here, we present widely applicable protocols to synthesize and characterize organo-functionalized silica aerogels with high surface area (356-1177 m(2)/g) and high mass loadings of surface functional groups (1.0-4.9 mmol/g, 0.9-3.9 molecules/nm(2)). Wet silica gels are soaked into dilute solutions containing pre-hydrolyzed organofunctional trialkoxysilanes, followed by supercritical CO2 drying. The retention of the various functional groups in the dry aerogels is confirmed by FTIR and their concentrations quantified by solid-state NMR spectroscopy. The mild reaction conditions are compatible with all tested functional groups (silanol, ethoxy, trimethylsilyl, amino, vinyl, methyl methacrylate, epoxy, phosphonate), without the need to optimize for each specific functional silane, making the synthesis of organofunctionalized aerogels a routine task. (C) 2020 The Authors. Published by Elsevier Ltd.