title: Expanding mesoporosity of triblock-copolymer-templated silica under weak synthesis acidity.
abstract: With initial aging at low temperature for enough time, silicas with large mesoporosity were synthesized using triblock copolymer as template agent under weak acidities. SBA-15 with periodic mesostructure and short mesochannels could be synthesized at pH 2.5-3.0 within weak acidity range, and the surface areas, pore diameters and pore volumes reached up to ca. 1000m(2)/g, 8.8nm and 2.0cm(3)/g, respectively, which were significantly higher than those of the conventional SBA-15 synthesized under strong acidities. Mesoporous silica with wormhole structure and abundant textural porosity was formed at pH approximately 3.5. The increased hydrophobic volume of the copolymer micelles at elevated pH values was responsible for the enlargement of mesoporosity in the products. The materials synthesized under weak acidities showed lower hexagonal ordering in comparison to the general SBA-15 synthesized under strong acidities because the decreased hydronium ion concentration induced relatively weaker assembly forces during the synthesis. Nonetheless, the short mesochannels and large pore diameter in the products might be beneficial to some applications in which fast diffusion of molecules is required.
authors.affiliation: Department of Environmental Nano-materials, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
authors.forename: Jinjun
authors.initials: J
authors.lastname: Li
authors.forename: Qin
authors.initials: Q
authors.lastname: Hu
authors.forename: Hua
authors.initials: H
authors.lastname: Tian
authors.forename: Chunyan
authors.initials: C
authors.lastname: Ma
authors.forename: Landong
authors.initials: L
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Hao
authors.forename: Shizhang
authors.initials: S
authors.lastname: Qiao
mesh_terms: D006863:Hydrogen-Ion Concentration; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: C509969:SBA-15; D012822:Silicon Dioxide