SYNTHESIS OF MESOPOROUS SILICA WITH NOVEL STRUCTURES USING RIGID BOLAFORM AMMONIUM SURFACTANTS

摘要

Mesoporous silica with a novel structure (FDU-11) has been prepared for the first time by using a rigid bolaform tetra-head-group quaternary ammonium surfactant: [(CH_3)_3NCH_2CH_2CH_2N(CH_3)_2CH_2(CG_2)_(11)OC_6H_4C_6H-4O(CH_2)_(11)CG_2N(CH_3)_2CH_2CH_2CH_2N(CH_3)_3]~(4+).4Br~- under an alkaline condition. X-ray diffraction (XRD) and transmission electron microscope (TEM) studies show that the mesoporous silica FDU-11 may have a low symmetric tetragonal mesostructure with P4/mmm space group. N_2 sorption isotherms show that calcined mesoporous silica FDU-11 has the BET surface area of 281 m~2/g, pore size of 2.05 nm and the pore volume of 0.36 cM~3/g. A phase transformation from FDU-11 into another unknown mesoporous silica structure by a hydrothermal treatment is observed, suggesting the intermediate nature of the FDU-11 mesophase.