Synthesis of Hollow Silica Nanoparticle Aggregates from Asymmetric Methyltrimethoxysilane Using a Modified SBA-15 Method

This work presents the synthesis and characterization of hollow silica particles that were fabricated with the asymmetric methyltrimethoxysilane (MTMS) as the only silica precursor, by using a modified SBA-15 synthesis method, for the first time. The MTMS concentration was varied in the range from 0.300 to 0.900 M. The hollow silica nanoparticulate material characteristics were compared to those of SBA-15 silica made by using tetraethyl orthosilicate. The hollow silica nanoparticle aggregates (named as MS-Asym) showed varied nanoparticle shapes from irregular to close to spherical, with multiple hollow pores as characterized by SEM and TEM. This result is very different from SBA-15, which has a ropelike shape. X-ray diffraction data showed that the MS-Asym silica samples were disordered compared to the ordered SBA-15. Nitrogen sorption measurements suggested that the SBA-15 is mainly mesoporous, whereas MS-Asym has a combined microporous and mesoporous structure. Furthermore, attenuated total reflectance-Fourier transform infrared spectroscopy spectra infer a different polymerization mechanism occurs for MS-Asym compared to that of SBA-15 silica.