Size and density dependent sedimentation analysis of advanced nanoparticle systems

Sedimentation coefficient distributions of the polystyrene–silica nanoparticles as a function of duration of polymerization. I: pure silica particles, II: intermediate hybrid particles and III: final hybrid particles. Various functional colloidal systems like polymer grafted inorganic particles, complex multi-component mixtures, organic–inorganic hybrid particles, inorganic–inorganic core–shell particles and swellable particles were characterized by sedimentation coefficient analysis in analytical ultracentrifuge owing to the accurate correlation of the sedimentation coefficient with variations in size and density of the materials. The sedimentation coefficient is absolute in nature and does not require any property information beforehand. By following the changes in the sedimentation coefficient and its distribution, it could be established if the polymer grafting on the surface of the inorganic particles took place or if the organic–inorganic or inorganic–inorganic hybrid was formed or if the particles were strongly crosslinked or swellable. The complex particle mixtures were also quantified for the number of components contained in them and their exact amounts by following the sedimentation coefficient distributions.