Polypyrrole grafting onto the surface of pyrrole-modified silica nanoparticles prepared by one-step synthesis

The grafting of polypyrrole onto the surface of modified silica nanoparticles has been investigated. These silica nanoparticles were modified with pyrrole moieties prepared by the well-known Stober method in one-step starting from TEOS and a pyrrole-bearing trialkoxysilane compound. The effects of various reaction conditions, including reaction time, solvent, and molar ratio of water to alkoxy groups, have been investigated in order to obtain pyrrole-modified silica nanoparticles with the optimal core–shell structure and the smallest possible particle size. The grafting was carried out in aqueous FeCl3 solution containing the modified silica nanoparticles, with pyrrole monomers already adsorbed on the surface of the particles by soaking. Several analytical tools have been employed to characterize the particles and to assess the degree of grafting, namely TEM, SEM, TGA, FTIR, and XPS. The final polypyrrole-grafted silica nanoparticles obtained had a mean diameter of about 220 nm and 50 wt.% of grafted polypyrrole with respect to the total weight of polypyrrole formed around the surface of the cores.