Abstract
Mercaptopropyl-functionalized mesoporous silica nanoparticles with c2mm symmetry and short-pitch helical channels were prepared by the cocondensation synthesis in the dilute solution of cetyltrimethylammonium bromide and tetraethylene glycol dodecyl ether (C 12 EO 4 ) under alkaline conditions. The amount and distribution of the covalently coupled organic groups within the nanoparticles were investigated. Interestingly, the mesostructure transformed toward p6mm phase when the amount of mercaptopropyltrimethoxysilane was increased, and a reverse p6mm-to-c2mm transformation took place as the mole percentage of C 12 EO 4 was further increased. The presence of C 12 EO 4 was also found crucial for helical arrangement of the channels. In situ small-angle X-ray scattering measurements showed that the addition of the functional silane slightly accelerated both the growth and structural deformation of the materials. The results were discussed based on the kinetics of the cooperative assembly of silicate species and the micelles of mixed surfactants and the interplay between the hydrolyzed silanes and surfactant molecules. © 2011 Elsevier Inc. All rights reserved.