Preparation and reaction mechanism of PS/SiO₂ composite nanoparticles

A novel method, i.e., batch process was used to prepare PS/SiO₂ composite nanoparticles with both yield and binding efficiency high above 95%. Compared with traditional pre-treated method, it was easy and had a good repeatability in batch process. There was little difference in average particle sizes, morphologies and dispersibility of the final composite nanoparticles obtained between two methods. The reaction mechanism of 3-methacryloxypropyltrimethoxysilane(MPTMS) in batch process was described in this report, proving that the role of MPTMS could be coupling agent, crosslinking agent or both by controlling its amount. The kinetics, which was opponent to that of some similar system reported previously, was investigated and well explained by the schematic model. The morphology and structure of composite particles were discussed as well. There are about 5-6 primary silica beads per composite particles, which formed a cluster. The core of the composite nanoparticles was made up of the cluster and PS grafted and encapsulating the cluster to form the shell.