Investigating silica coating of spontaneously formed Pickering emulsions and zein-based composite particles

Abstract

The goal of this thesis was to make magnetic composite particles with a layer of functionalized silica for magnetic separation. Two different composite particles were investigated for this. One is a special Pickering emulsion that forms spontaneously and consists of TPM (3-(trimethoxysilyl)propyl methacrylate) and magnetite nanoparticles. The other one is zein-based. Zein is a protein that can form composite particles with magnetite nanoparticles by a simple co-precipitation. Both systems are interesting because of their simple formation and the ability to contain different nanoparticles. While both systems are interesting they are relatively new and during this thesis more research was done to acquire a better understanding of their properties. These composite particles were coated with silica using several different methods based on the Stöber method and on the precipitation of sodium silicate. The coating of these particles with silica was to increase the stability of the composite particles and to enable the diverse possibilities of functionalizing (with for example a catalyst) the particles. During the silica coating it was found that optimization was required for the methods used. After doing a number of experiments it was found using TEM that both systems could indeed be coated with silica. More experiments showed that the methods were reproducible, that by changing several conditions that the silica shell could change in size and shape, and that it is possible to make hollow silica spheres filled with nanoparticles.