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

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 (& alpha;& Omicron;H) of -4.08 per nm2 which could improve their surface modification for being used in diverse biomedical applications including drug delivery.