Revisiting Polymer Coatings on Nanoparticles: Correlation between Molecular Weight and Coating Thickness in Chain Transfer Polymerizations

Abstract

Various poly(methyl methacrylate) (PMMA) and poly(acrylonitrile) (PAN) coated silica nanoparticles were synthesized via chain transfer polymerization with the goal to assess the coating behavior and characterization of polymer coated silica nanoparticles with monomers of different reactivities. The particles were characterized by thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM) and correlated to the free PMMA/PAN formed in the crude reaction mixture characterized with size exclusion chromatography (SEC). It was found that the mass loss observed in TGA and coating thickness obtained from TEM micrographs correlate strongly with the average polymer chain-length in the crude reaction mixture.