Preparation and characterization of twisted periodic mesoporous ethenylene-silica nanorods

Twisted periodic mesoporous ethenylene-silica nanorods were prepared using cetyltrimethylammonium bromide in concentrated aqueous ammonia solutions at the stirring rate of 600 rpm. The pore channels run along the long axis of the nanorod. The helical pitches are about 1.2 micrometers. Small-angle X-ray diffraction pattern was indexed to the p6 mm hexagonal symmetry. The morphologies of the ethenylene-silicas are sensitive to stirring conditions. For example, twisted nanorods and spiral nanofibers combined with nanospheres were obtained under static condition. With increasing stirring speed, both the length and helical pitch of the nanorod increased slightly. With decreasing the concentration of ammonia, the particle lengths decreased, while the particle diameters increased. Chiral mesostructures were obtained when the ammonia concentration was a parts per thousand yen 20 wt%. The formation of the twisted mesoporous ethenylene-silica nanorods was studied by taking TEM images after different reaction time.