Mesoscopic simulation of surfactant/silicate self-assembly in the mesophase formation of SBA-15 under charge matching interactions

Ordered mesoporous silica SBA-15 with uniform hexagonal tunable mesopore channels attracts significant interest of the intensive studies and finds numerous applications in adsorption, catalysis, controlled release and drug delivery, etc. It is generally considered that such a unique hexagonal mesopore system of SBA-15 is formed via the cooperative self-assembly of partially protonated nonionic surfactants and positively charged silicate oligomers. However, the information about the assembly mechanism and the phase transformation at mesoscopic level is still insufficient due to the limitation of experimental technology. In this paper, Mesoscopic Dynamics (MesoDyn) simulation method is employed to investigate the phase transformation in the synthesis of SBA-15 with a simple Gaussian model, and a successive phase transition process composed of various mesophases of SBA-15 including spheroidal, columnar, and hexagonal phase are obtained. Moreover, the effects of charge matching interactions between surfactants and silicate species on the mesophase morphology of SBA-15 are further discussed. The obtained results are in good agreement with the ab initio calculations and the experimental results reported before, which indicates that the MesoDyn simulation method can be used to fundamentally validate and interpret the “surfactant/silicate species cooperative formation mechanism” of ordered mesoporous materials.