| 초록 |
Coating of nanoparticles with a layer of a different material is used as a mean to modify their surface chemical, reactive, catalytic, optical, or magnetic properties[1, 2]. Such core-shell particles can often be prepared by controlled precipitation of inorganic precursors on the core particles, in some cases assisted by coupling agent with the combination silica and silver. A second approach is the layer by layer technique, in which successive layers of anionic particles are deposited, alternated by layers of a cationic polymer. Disadvantages are that a lot of aggregate polymer particles is also incorporated in the shell and that the preparation of nanoparticle coated polymer is complicated. This is why multiple steps are often used to obtained thicker coatings. Particles coated with titania are generally exceptionally difficult to synthesize because the titania precursors are highly reactive, making it difficult to control their precipitation.Koishi [3] developed a fine particles could be made to adhere to the surface of core particles by a binary particles mixture by using a dry impact blending method. This procedure has been employed for the improvement of powder properties and in mixing homogeneously a small amount of material such as drugs and pigments. It was confirmed experimentally that small particles were fixed on large particles when the ratio of the diameter of the large particles to that of the small particle was larger than 10:1. This easily causes the core particles to aggregate or the titania nanoparticles to form separate particles. Titania coated particles are very useful as catalysts and as white pigments[4]. In this work, titania nanoparticles encapsulation on polystyrene particles, using dry impact blending process is described. The behavior of encapsulation of polystyrene bead study has been carried out using titania nonoparticles as a shell. In the dry impact blending of a binary particles mixture which contains elasticity of polystyrene particles and the action of impulsive forces during the operation were important factors in the effective preparation of the titania particles coated polystyrene bead. In this paper, we describe the important factors for an effective nanoparticles coated polystyrene bead were discussed using scanning electron microscopy (SEM) and particle analyzer. |
