A multinuclear solid-state magnetic resonance study on submicrometer-sized SiO2 particles encapsulated by a PMMA shell

Submicrometer-sized silica particles encapsulated by poly(methyl methacrylate) via a novel methodology have been characterized by means of solid-state high-resolution NMR techniques. The organic-inorganic composite prepared under static conditions, using our previously published method, comprised silicacore-shell particles of approximately 180 nm functionalized with 3-(trimethoxysilyl)propyl methacrylate and an outer coating of poly(methyl methacrylate) with an approximate 10 nm thickness, shown by transmission electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis and differential scanning calorimetry. A systematic solid-state nuclear magnetic resonance study based on Si-29 and C-13 high-resolution techniques was performed herein for the submicrometer particles at the various stages of synthesis, thus characterizing the organic and inorganic components as well as their interface. The presence of TMSPM and PMMA was confirmed and the structural features of the TMSPM species characterized. Moreover, from a comparative study of functionalized silica samples with different average particle size, it was possible to reveal the significant effect of this parameter on the condensation reactions involved in the synthesis of such samples.