Morphological control of mesoporous silica SBA-15 synthesized at low temperature without additives

Abstract

Fiber-like or rod-like mesoporous SBA-15 silicas with different lengths and diameter of macrostructures and pore diameter could be synthesized by the self-assembly of silica-surfactant (commonly used Pluronic P123 (EO20-PO70EO20) as a structure-directing agent) through careful control of the synthetic temperature and stirring time without any additives. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms are used to characterize these mesoporous silica materials. Compared with those reports on conventional SBA-15, our work is focused on one-step synthesis and the morphological control of ordered mesoporous silica synthesized at low temperature under low concentration of P123 (0.67 wt%) without the addition of inorganic salts, where pre-hydrolyzed silica species may favor the self-assembly of silica-polymer hybrid micelles. Moreover, the pore diameter of fiber-like SBA-15 synthesized at 40 °C is slightly smaller than that of conventional SBA-15, revealing that the average micellar radius of P123 micelles in this low concentration of P123 solution was almost same as that for the conventional synthesis of SBA-15.