Synthesis of mesoporous silica with novel structures using rigid bolaform ammonium surfactants

Abstract

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: [(CH3)(3)NCH2CH2CH2CH2N(CH3)(2) CH2(CH2)(11)OC6H4C6H4O(CH2)(11)CH2N(CH3)(2)CH2CH2CH2N(CH3)(3)](4+)center dot 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/mm:space group. N-2 sorption isotherms show that calcined mesoporous silica FDU-11 has the BET surface arc 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-1 into another unknown mesoporous silica structure by a hydrothermal treatment is observed, suggesting intermediate nature of the FDU-11 mesophase.