cm030622u_si_001.pdf (222.8 kB)
Morphological Control of Rod- and Fiberlike SBA-15 Type Mesoporous Silica Using Water-Soluble Sodium Silicate
journal contribution
posted on 2004-03-09, 00:00 authored by Katsunori Kosuge, Tetsu Sato, Nobuyuki Kikukawa, Makoto TakemoriWell-defined rodlike and fiberlike SBA-15 mesoporous silicas have been selectively
synthesized from an aqueous reaction mixture consisting of a commercial sodium silicate
solution, P123 triblock copolymer and HCl. The morphologies and physicochemical properties
of the products were found to be greatly affected by the shearing stress exerted by cylindrical
silicated-surfactant micelles in a flowing solution, referred to hereafter as “shearing flow”.
Monodispersed rodlike particles ca. 0.5-μm wide and ca. 1−2-μm long were formed under
static reaction conditions, whereas continuous stirring of the reaction mixture led to the
formation of fiberlike silicas with lengths of several hundred micrometers and a relatively
uniform width of ca. 10 μm. The effects of the synthesis conditions, such as the initial ratio
of the reactants, time, temperature, and the acid source, in addition to shearing flow, on
particle morphologies were investigated. Fiberlike silicas of various lengths were obtained
from a relatively wide range of synthesis conditions, while monodispersed rodlike silicas
were prepared under very specific conditions. Each fiberlike product was found to be
comprised of a bundle of fibers, with each fiber formed by the coupling of rodlike particles
of almost identical size, irrespective of different synthesis conditions.