Effect of two-step sol-gel reaction on the mesoporous silica structure

被引:52
作者
Choi, DG [1 ]
Yang, SM [1 ]
机构
[1] Korea Adv Inst Sci & Technol, Dept Chem & Biomol Engn, Yuseong Gu, Taejon 305701, South Korea
关键词
two-step sol-gel reaction; mesoporous silica; SBA-15; mesocellular foam;
D O I
10.1016/S0021-9797(03)00020-1
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
the present study, we investigated the effects of two-step sol-gel reaction by abrupt pH change on the SBA-15 and mesocellular silica foams (MCF). Mesoporous silica was fabricated by using triblock copolymer templates (poly(ethylene oxide) and poly(propylene oxide)). The prepared silica structure was characterized by X-ray diffraction, transmission electron microscopy, and N-2 sorption experiment. Specifically, we prepared SBA-15 with long-range two-dimensional hexagonal arrangement of 3 to 6-nm feature spacing and MCF with larger pores of a few tens of nanometers. The pore size and ordering were influenced by pH change in a two-step sol-gel reaction and the concentration of organic solvent. Although well-ordered hexagonal arrangement of mesopores was prevalent in acidic conditions, the materials synthesized by a single-step reaction in neutral or basic conditions possessed gel-like structure without mesopores. However, the present two-step reaction (low pH sol-gel reaction followed by high pH reaction) not only produced mesoporous materials but also provided controllability of the pore size. In particular, mesoporous structures with pore sizes as large as those of MCF were successfully fabricated by the two-step reaction without using organic swelling agents. As expected, when xylene was added as a swelling agent, the pore size increased with the xylene/copolymer weight ratio. (C) 2003 Elsevier Science (USA). All rights reserved.
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页码:127 / 132
页数:6
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