Heat-Mediated Transformation of PMMA-SiO2 Core-Shell Particles into Hollow SiO2 Particles

Changes in the morphology and structure of the core-shell particles of polymethyl methacrylate-silicon dioxide and hollow SiO2 particles during their heat treatment were studied by electron microscopy, infrared spectroscopy, and X-ray diffraction. The polymeric core of the PMMA-SiO2 hybrid particle was found to undergo an unusual transformation when exposed to the electron microscope beam: its shrinkage occurs through the formation of a spherical cavity. It was shown that the process of silica-shell formation occurs in the temperature range of 200-600 degrees C and is accompanied by the loss of vinyl- and OH-groups. It was determined by the method of X-ray diffraction, that in the place of the interaction of PMMA and the shell, the degree of ordering of the polymer is higher than that in the volume of the polymer core. It was shown that the frequency of the TO3-vibrational mode (asymmetric stretching vibrations of the Si-O-Si bonds) increases with an increase in the annealing temperature, which is associated with the densification of the silicon dioxide shell.

Automated summary

This study investigated the morphological and structural changes of polymethyl methacrylate-silicon dioxide core-shell particles and hollow SiO2 particles during heat treatment using electron microscopy, infrared spectroscopy, and X-ray diffraction. The polymeric core of the PMMA-SiO2 hybrid particle exhibited an unusual transformation, shrinking through the formation of a spherical cavity when exposed to the electron microscope beam. The process of silica-shell formation occurred in the temperature range of 200-600 degrees C and was accompanied by the loss of vinyl- and OH-groups.