title: Preparation of the monolith of hierarchical macro-/mesoporous calcium silicate ultrathin nanosheets with low thermal conductivity by means of ambient-pressure drying.
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.
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Jilin
authors.initials: J
authors.lastname: Bai
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China. liyuanzhi66@hotmail.com.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Jiwei
authors.initials: J
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Mingyang
authors.initials: M
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Zeng
authors.affiliation: State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, P.R. China.
authors.forename: Xiujian
authors.initials: X
authors.lastname: Zhao
keywords: ambient-pressure drying; hydrothermal synthesis; mesoporous materials; nanostructures; silicates