Fast fabrication of mesostructured MCM-41-type nanoparticles by microwave-induced synthesis

Abstract

This work reports the synthesis of mesoporous MCM-41 nanoparticles by applying microwave radiation (MWR) in the range of 400–1000 W. Silica nanoparticles were produced at short time (10 min) and low power radiation (400 W) which showed large surface area (SBET ∼1000 m2g-1) and a suitable chemical surface composition. Both, scanning and transmission electron microscopies (SEM and TEM) revealed that the mesoporous silica had a nanometric size close to 100 nm with a predominant spherical morphology. Also, it was found that the particles were smaller and agglomerated at higher microwave radiation power (>600 W) and longer heating time (>10 min). On the other hand, low microwave radiation power (400 W) was sufficient to obtain MCM-41 with high surface area (1182 m2g-1) keeping the same particle size. Under MWR synthesis, pore diameters slightly expanded up to ∼4.00 nm which are larger for those obtained by the hydrothermal method (∼2.0 nm). According to the FTIR results, the surface of the sample labeled as MCM400W10 exhibited a number of free silanol groups (αΟΗ) of ∼4.08 per nm2 which could improve their surface modification for being used in diverse biomedical applications including drug delivery.