Preparation of the Monolith of Hierarchical Macro‐/Mesoporous Calcium Silicate Ultrathin Nanosheets with Low Thermal Conductivity by Means of Ambient‐Pressure Drying |
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| Authors: | Jilin Bai Prof. Yuanzhi Li Jiwei Xiang Lu Ren Mingyang Mao Min Zeng Prof. Xiujian Zhao |
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| Affiliation: | State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, P.R. China |
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| Abstract: | Calcium silicate monolith was prepared by the hydrothermal reaction of a slurry of SiO2, calcium hydroxide, and surfactant (OP‐10) obtained by high‐energy ball milling, followed by drying at ambient pressure. By using this strategy, the shrinkage due to the collapse of pores during the drying of porous materials, which is a commonly observed phenomena, was successfully avoided. It has a unique microstructure of hierarchical macro‐/mesoporous ultrathin calcium silicate nanosheets with a layered gyrolite crystalline structure. Very interestingly, the calcium silicate nanosheets can be peeled off to give a single‐layer nanosheet (1.23 nm) of gyrolite by ultrasonication. The monolith has a low apparent density (0.073 g cm?3) and low thermal conductivity (0.0399 W K?1 m?1). The reasons behind why the formation of the unique hierarchical macro‐/mesoporous ultrathin nanosheets avoids shrinkage during the hydrothermal reaction and drying, and considerably decreases the thermal conductivity, is discussed. |
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| Keywords: | ambient-pressure drying hydrothermal synthesis mesoporous materials nanostructures silicates |
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