Department of Chemistry, College of Staten Island, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, USA.
Langmuir. 2010 Sep 21;26(18):14871-8. doi: 10.1021/la102228u.
Ultralarge-pore FDU-12 (ULP-FDU-12) silicas with face-centered cubic structures (Fm3m symmetry) of spherical mesopores were synthesized at low initial temperature (∼14 °C) using commercially available PEO-PPO-PEO triblock copolymer Pluronic F127 as a micellar template and xylene as a micelle expander. Xylene was selected on the basis of its predicted higher swelling ability for the Pluronic surfactant micelles in comparison to 1,3,5-trimethylbenzene that was used previously to obtain large-pore FDU-12. The optimization of the synthesis conditions afforded as-synthesized ULP-FDU-12 materials with unit-cell parameters up to 56 nm, which is comparable to the highest reported values for Fm3m structures templated by custom-made surfactants. Calcined silicas were obtained with unit-cell parameters up to 53 nm and pore diameters up to ∼36 nm (for N(2) adsorption at 77 K, the capillary condensation relative pressure was up to 0.938). The preferred silica source was tetraethylorthosilicate, but tetramethylorthosilicate was also found suitable. The pore diameter was dependent on the unit-cell size of the as-synthesized material, but was further tuned by adjusting the time and temperature of the treatment in the HCl solution. If the synthesis was performed at low temperature only, highly ordered closed-pore silicas were obtained at calcination temperatures as low as 450 °C. On the other hand, the hydrothermal treatments, including the acid treatment at 130 °C, afforded silicas with large pore entrance sizes. The present synthesis constitutes a major advancement in the synthesis of ordered silicas with very large open and closed spherical mesopores.
采用市售的嵌段共聚物聚环氧乙烷-聚环氧丙烷-聚环氧乙烷（PEO-PPO-PEO） Pluronic F127 作为胶束模板，二甲苯作为胶束膨胀剂，在较低的初始温度（约 14°C）下合成具有面心立方结构（Fm3m 对称性）的大孔 FDU-12 （ULP-FDU-12）硅。选择二甲苯是基于其对 Pluronic 表面活性剂胶束的溶胀能力预计高于之前用于获得大孔 FDU-12 的 1,3,5-三甲苯。优化合成条件可得到单元胞参数高达 56nm 的未煅烧 ULP-FDU-12 材料，这与用定制表面活性剂模板化的 Fm3m 结构的最高报道值相当。煅烧硅得到的单元胞参数高达 53nm，孔径高达约 36nm（在 77K 下用 N2 吸附，毛细凝聚相对压力高达 0.938）。首选的硅源是正硅酸乙酯，但也发现正硅酸甲酯是合适的。孔径取决于合成材料的单元胞尺寸，但通过调整在 HCl 溶液中处理的时间和温度进一步调节。如果仅在低温下进行合成，在煅烧温度低至 450°C 时即可得到高度有序的封闭孔硅。另一方面，水热处理，包括在 130°C 下的酸处理，可得到具有大孔入口尺寸的硅。本合成在合成具有非常大的开放和封闭球形介孔的有序硅方面取得了重大进展。
