HRTEM imaging of mesoporous phase transition from hexagonal P6mm to cubic Ia 3¯d symmetry

The Successful synthesis of large pore bicontinuous cubic mesoporous solid using the triblock co-polyme PEO-PPO-PEO (P123) as a template and 3-mercaptopropyltriethoxysilane (MPTS) and tetraethylorthosilicate (TEOS) as silica sources has been recently reported. We present here High Resolution, Transmission Electron Microscopy (HRTEM) imaging of samples of these and related mesoporous material prepared under aqueous and hydrothermal conditions. This provides evidence suggesting that the transition from the hexagonal to cubic bicontinuous structure is governed by the amount of MPTS added to the synthesis gel and the synthesis temperature, for conditions described. In addition we also investigate the formation of the bicontinuous cubic structure analogous to MCM-48 through the addition organosilane, phenyltriethoxysilane.