Synthesis of organic-inorganic hybrid core-shell nanoparticles and particle size control
The control of the morphology of nanoparticles is a hot issue all over the world.Organic-inorganic materials can be tailor made with an infinite number of architectures and in diverse forms conveniently.A new type of organic inorganic hybrid material was reported to be synthesized by emulsion polymerization by using the monomers which contained alkoxysilane groups.However,polymerization and morphology could hardly be controled during the emulsion process, because the alkoxysilane group was easy to be subjected to hydrolysis and condensation by sol gel process which decreased the stability of the latex.In the present work, organic inorganic hybrid core shell nanoparticles were synthesized by seeded emulsion polymerization.Through morphology design, polystyrene, as seeded cores, was synthesized firstly, then 3 trimethoxysilyl propyl methacrylate (MPS) was added to form MPS styrene copolymer shell on the surface of polystyrene core. Owing to the hydrolysis condensation of organic alkoxysilane groups in MPS,the organic inorganic hybrid shell was formed through sol gel process.The core shell structure was interpreted by thermodynamical representation and characterized by transmission electron microscopy (TEM).The nonionic surfactant used would decrease the stability of the latex.In acidic condition the latex turned into gel just after the addition of MPS,while,in basic condition the particle number decreased obviously, and the latex kept almost stable in neutral condition.The higher the MPS concentration in the emulsion was,the less stability the latex had.Adding MPS continuously could keep the latex more stable and the particle size could be controlled by this method.Then, the core of this kind of hybrid nanoparticles could be dissolved to yield hollow nanocapsules, with the proportion of the void volume 40 1%.