Comparative analysis of structural and morphological properties of large-pore periodic mesoporous organosilicas and pure silicas

Bao, Xiao Ying ; Zhao, X. S. ; Qiao, S. Z. ; Bhatia, S. K. (2004) Comparative analysis of structural and morphological properties of large-pore periodic mesoporous organosilicas and pure silicas Journal of Physical Chemistry B, 108 (42). pp. 16441-16450. ISSN 1089-5647

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp047479s

Related URL: http://dx.doi.org/10.1021/jp047479s

Abstract

A systematic study on the structural properties and external morphologies of large-pore mesoporous organosilicas synthesized using triblock copolymer EO20PO70EO20 as a template under low-acid conditions was carried out. By employing the characterization techniques of SAXS, FE-SEM, and physical adsorption of N2 in combination with αs-plot method, the structural properties and external morphologies of large-pore mesoporous organosilicas were critically examined and compared with that of their pure-silica counterparts synthesized under similar conditions. It has been observed that unlike mesoporous pure silicas, the structural and morphological properties of mesoporous organosilicas are highly acid-sensitive. High-quality mesoporous organosilicas can only be obtained from synthesis gels with the molar ratios of HCl/H2O between 7.08 × 10−4 and 6.33 × 10−3, whereas mesoporous pure silicas with well-ordered structure can be obtained in a wider range of acid concentration. Simply by adjusting the HCl/H2O molar ratios, the micro-, meso-, and macroporosities of the organosilica materials can be finely tuned without obvious effect on their structural order. Such a behavior is closely related to their acid-controlled morphological evolution: from necklacelike fibers to cobweb-supported pearl-like particles and to nanosized particulates.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:2684
Deposited On:08 Oct 2010 09:01
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