Abstract
We develop a strategy for preparing water-based dispersions of polymer/TiO&sub2; nanospheres that can be used to form composite materials applicable in various fields. The formed hybrid nanospheres are monodisperse and possess a hierarchical structure. It starts with the primary TiO&sub2; nanoparticles of about 5 nm, which first assemble to nanoclusters of about 30 nm and then are integrated into monomer droplets. After emulsion polymerization, one obtains the water-based dispersions of polymer/TiO&sub2; nanospheres. To achieve universal size, it is necessary to have treatments with intense turbulent shear generated in a microchannel device at different stages. In addition, a procedure combining synergistic actions of steric and anionic surfactants has been designed to warrant the colloidal stability of the process. Since the formed polymer/TiO&sub2; nanospheres are stable aqueous dispersions, they can be easily mixed with TiO&sub2;-free polymeric nanoparticle dispersions to form new dispersions, where TiO&sub2;-containing nanospheres are homogeneously distributed in the dispersions at the nanoscale, thus leading to various applications. As an example, the proposed strategy has been applied to generate polystyrene/TiO&sub2; nanospheres of about 100 nm in diameter.