Synthesis And Characterization Of Polymer/Inorganic Compound Core-shell Particles

In recent years, there has been increasing interest in core-shell materials due to its potential in developing novel materials with unique functions. The exterior coating structure is very useful in many applications in order to enhance the stability of dispersions, to protect the particles from interaction with surrounding medium, and to endow the core optical, conductive, magnetic, adsorptive, and surface reactive properties. Polymer organic-inorganic core-shell particles attract scientists attention because it realize the molecular scale fabrication. Combining the properties of organic and inorganic components, this kind of materials has excellent and special capability as compared to its components. The inorganic shell can improve the internal domain thermal stability, mechanical strength and scratch resistance. The latex core exhibits elasticity and film formation ability. The latex coated with inorganic matter impart the core-shell particles with improved chemical and physical properties, creating synergistic effects.Many studies for coating process have been proceeded comprised of in situ deposition as well as layer-by-layer (LbL) technique. In situ deposition is to prepare the core-shell particles by controlled precipitation of inorganic precursors onto the core domain. The second approach, LbL technique is versatile method to synthesize core-shell materials. It's based on electrostatic interaction between particles, the species having opposite charge with core and absorbing on the surface of the core. The coated particles subsequently centrifuged and washed could be deposited in order to obtain the desirable coating thickness. Disadvantages of this technique are not only the time-consuming sequential polyelectrolyte deposition cycles and purification steps, but also the incorporation of redundant polyelectrolyte into shell. Chemical coprecipitation is first to immerge the polymer colloid with inorganic salts, next, by using in situ reaction, the organic core were coated with inorganic shell.Titania is of interest as both a catalyst and a catalyst support. However, titania when present as a high surface area powder is not thermally stable and loses surface area readily. The production of core-shell materials comprising TiO2 nanoparticles is expected to be of benefit to various applications. Titanium dioxide has been coated on various inorganic and organic particles using titania precursors and by carrying out subsequent reactions on the particle surface. The preparation of TiO2-coated particles is generally exceptionally difficult due to the highly reactive property of the titania precursors, making it difficult to control their precipitation. This usually causes the core particles to aggregate or the titania to form separate particles.In this article, the TiO2-coated particles can be prepared in a simple method. First, functional PS particles were synthesized by copolymerizing a polymerizable surfactant with styrene. Next, we used the stable dispersions of polystyrene nanoparticles as templates, with which we coated with titania by in situ hydrolysis of TBT. No surface treatment and centrifugation/redispersion cycle process were needed during the whole experiment. The core-shell particles can be turned into spherical hollow titania shells by calcinations of the dried particles in a furnace. This way, we obtained colloidal crystals consisting of hollow shells. In addition, by changing different kinds of comonomer, polymer particles with functional surfaces were prepared. Coating process with SiO2,ZnS can be achieved.It is well known that silver is superior to other nanostructured metal materials for many reasons such as electrical conductivity, antimicrobial effects, optical properties and oxidative catalysis. Therefore, fabrication of silver-coated latex particles is of special interest, and several routes have been reported in the literature, including surface precipitation reaction, thermal evaporation techniques or sputtering onto latex particles and self-assembly. However, in most cases, irregular thickness, a large number of non-coated particles, merely metal islands and incomplete surface coverage were usually obtained by these methods. Particles coated with silver nanoshells are generally difficult to synthesize because the reduction reaction is too fast to be controlled. Thus, we attempted to slow the rate of the silver reduction and coated PBuA latex particles with silver by the decomposition of the silver complex. Monodisperse brush polymer nanospheres were synthesized by copolymerizing one kind of polymerizable surfactant with butyl acrylate. BDDA was used as a cross-linker during the semicontinuous emulsion polymerization. Ag-PBuA composite microspheres were abtained by using polymer microspheres as templates. Using the same templates, we attempted to abtain Al2O3-PBuA composite microspheres. The composite particles were characterized by IR, TEM, and XRD.The study for magnetic polymer composite particles began in the seventies of the 19th century. It is a microparticles with a certain magnetism and a special structure by a proper method to combine polymer and magnetic inorganic matter. Colloidal particles with magnetic properties have become increasingly important both technologically and for fundamental studies due to the tunable anisotropic interaction they exhibit. Particles covered with magnetic materials have been used or proposed as beads for cell separation, or as pigments, catalysts, coating, flocculents, toners, etc. In this work, amphiphilic graft copolymer consisting of an acrylic backbone and poly(ethylene glyol) chains was prepared and characterized. It was used as surfactant to stabilize emulsion polymerization of St or BuA. The effect of the amount of the surfactant was investigated. Finally, the feasibility of using PS emulsion particles as templates, with which we coated with Fe3O4 by in situ reaction of Fe3+ and Fe2+ in the present of OH-1 was studied.In summary, by using different kinds of emulsifier, functional polymer particles were successfully prepared. And in a easy way, various kinds of inorganic/polymer composites were obtained. No surface treatment and centrifugation/redispersion cycle process were needed during the whole experiment.