Synthesis of hollow-shell MCM-48 using the ternary surfactant templating method

Hollow-shell mesoporous MCM-48 silica has been hydrothermally synthesized in basic medium by a new method using ternary mixtures of cationic surfactant cetyltrimethylammonium bromide (CTAB), nonionic surfactant poly(ethyleneglycol) monooctylphenyl ether (OP-10) and anionic surfactant sodium laurate (SL) as templates, with tetraethylorthosilicate (TEOS) as silicon source. The synthesis can be performed at an extremely low molar ratio of surfactant to silicon (0.05:1-0.07:1) and extremely low surfactant concentration (1.76-2.4 wt.%). Powder X-ray diffraction (XRD), N2 adsorption-desorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the synthesized samples. It suggests that the synergism effects of the ternary mixed system of cationic-neutral-anionic surfactants help to enhance the ability to form the micelles and favor the formation of cubic MCM-48 with high specific surface areas and well-defined three-dimensional channel systems. The results of 1H NMR provide a better understanding of the possible formation mechanism of micelles.