Temperature-Driven Structural Evolution during Preparation of MCM-41 Mesoporous Materials

Abstract In this study, we explored the structural evolution of MCM-41 mesoporous silica synthesized using water glass as the silicon source under varying hydrothermal crystallization temperatures, with a particular focus on the changes in pore size and structural order. Our experimental results revealed that as the hydrothermal crystallization temperature escalates from 100℃ to 160℃, there is a notable expansion in the lattice structure of MCM-41, accompanied by an increase in pore size. This phenomenon is attributed to the increase in the diameter of the micelles constituting MCM-41, resulting in an expanded distance between the axes of the micelles, while maintaining a relatively stable structural order. However, a further increase in temperature of 180℃-200℃ leads to a loss of material order. This is primarily due to the excessively high temperatures preventing the micelles from maintaining their two-dimensional hexagonal stacking structure, rendering them ineffective as templates for silica condensation. Additionally, the alkaline high-temperature environment contributes to the disruption of the mesoporous channels, resulting in a disordered material structure. The insights gained from this study are crucial for understanding the structural transformation of MCM-41 materials under different hydrothermal conditions and offer a new perspective for controlling the pore size and structural order of mesoporous materials.