Preparation of Core-Shell Polystyrene/ Silica Composite Microspheres and Hollow Silica Spheres

The core-shell polystyrene/silica composite microspheres with tailored dimensions and compositions were prepared by layer-by-layer self-assembling. The polymer cores were removed by calcination and hollow silica spheres with tailored wall thickness were produced. TEM photographs showed that silica nanoparticles formed a uniform shell round the core, which turned into a clear-cut hollow sphere after calcination. TG revealed that silica content within the composite microspheres increased with the assembled nano silica diameter. Both the successful assembly of Si02 and the complete removal of PS can be verified by FIIR comparison of PS, Si02, composite microspheres and the powders after heating treatment. With the same number layers of nanoparticles adsorpted on the latex cores, the larger the selected Si02 nanoparticles diameter (10nm, 20nm, 40nm), the larger the composite microspheres diameter, and the thicker the hollow spheres' wall.