Ultrasonic mediated synthesis of hexagonal benzene-bridged periodic mesoporous organosilicas

Abstract

A rapid synthesis route to synthesize highly ordered benzene-bridged periodic mesoporous organosilicas (PMOs) with the hexagonal mesostructures in a short time via the aid of ultrasonic irradiation is reported. By varying the time periods for the ultrasonic irradiation and hydrothermal treatment, the structural and textural properties of the resultant materials can be finely tuned. The resultant materials exhibited well ordered hexagonal mesostrucutres with surface areas in the range of 653–1097m2/g, pore volumes of 0.52–1.26cm3/g, and pore diameters in the range of 3.9–6.4nm, which are comparable to the conventional analogs. Different synthesis procedures, namely ultrasonic irradiation and hydrothermal treatment, have significant influence on the particle morphology and the change in morphology was evident from SEM analysis. It is of great interest that 13C solid-state NMR can reveal subtle changes in the overall arrangements of the carbon atoms in the phenylene rings embedded in the silica framework due to different synthesis procedures by simulating the 13C NMR spinning sideband manifolds. This study shows that the ultrasonic mediated synthesis route is an easy and effective way not only to significantly reduce the total synthesis time of PMOs from days to a few hours, but also to easily screen a wide range of synthesis conditions in order to optimize and scale-up their production.