Periodic mesoporous organosilica (PMO) materials with uniform spherical core-shell structure.

We report the synthesis of monodisperse, spherical periodic mesoporous organosilica (PMO) materials. The particles have diameters between about 350 and 550 nm. They exhibit a regular core-shell structure with a solid, non-porous silica core and a mesoporous PMO shell with a thickness of approximately 75 nm and uniform pores of about 1.7 nm. The synthesis of the core and the shell is carried out in a one-pot, two-stage synthesis and can be accomplished at temperatures between 25 and 100 °C. Higher synthesis temperatures lead to substantial shrinking of the solid core, generating an empty void between core and shell. This leads to interesting cavitation phenomena in the nitrogen physisorption analysis at 77.4 K.