Effects of synthetic routes on the compositional and structural properties of dendritic mesoporous organosilica nanoparticles: The unexpected reversed “double-edged sword” role of reaction time

Dendritic mesoporous organosilica nanoparticles (DMONs) have attracted increasing attention owing to the variety of appealing properties offered by the hybrid organic-inorganic framework and the central-radial pore structure. To date, two synthetic routes have been developed for the preparation of DMONs, including aqueous phase and water/oil bi-phasic systems. However, the impact of synthetic routes on the compositional and structural properties of the resultant nanomaterials remains largely unexplored. In the present work, we aim to gain insight on these two synthetic routes and have observed an unexpected reversed “double-edged sword” effect of reaction time on the compositional and structural properties of DMONs for two synthetic routes. For the aqueous phase route, prolonged reaction time is beneficial for improving the organosilica content, but leads to the loss of porous structure. In contrast, for the water/oil biphasic route, prolonging the reaction time causes the reduction of organic content in the products, but facilitates the formation of well-defined dendritic mesoporous structure. A “rate determine step” based mechanism has been proposed to explain these observations. Moreover, DMONs prepared from aqueous route possess higher organic content than those prepared from the biphasic route, which has resulted in a significantly higher hydro-stability. Our work unravels that synthetic routes largely determine the compositional and structural properties of DMONs, for which the reaction time needs to pay particular attention to achieve maximized organic content and well-preserved pore structure for optimal performance in desired applications.