Preparation of monodispersed microspheres with polymer core and SiO₂ shell structure

Polymer (PGMA, PGMA/PS)/SiO₂ core-shell monodispersed microspheres are more stable than polymer microspheres when they are used at high temperature or in organic solvent. To prepare the composite microspheres, monodispersed polymer (PGMA, PGMA/PS) microspheres were modified with amino-group at the first step, and then the microspheres were coated with SiO₂ shell by catalyzing the hydrolysis of tetra ethoxy silane (TEOS) and adsorbing the hydrolyzate. The obtained microspheres were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), laser particle analyzer, and mass loss of ablation. Polymer (PGAM, PGMA/PS)/SiO₂ core-shell monodispersed microspheres with diameter of 2 μm and 5 μm were successfully obtained. The shell thickness is in the range of several nanometers to tens of nanometers. The thicknesses of the shell are heavily influenced by the kinds of ammoniation reagents. The electrostatic self-assembly mechanism of ammoniated microspheres was evidenced by Zata potential.