Hydrophilic polymer/fumed silica hybrid nanoparticles synthesized via surface-initiated redox polymerization

Poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) chains were grafted onto the surface of functionalized fumed silica nanoparticles via a convenient surface-initiated redox polymerization method. Fumed silica nanoparticles (FSN) were first treated with 3-aminopropyltriethoxysilane (APTES) to form aminopropylated fumed silica nanoparticles (AFSN), followed by the surface-initiated redox polymerization of AA and MAA in the aqueous media stabilized by sodium dodecyl sulfate to synthesize PAA-g-FSN and PMAA-g-FSN hybrid nanomaterials. Cerium(IV) ammonium nitrate/aminopropyl group on the surfaces of AFSN was used as a redox initiation system. FT-IR and TGA results showed that PAA and PMAA chains are grafted on the FSN nanoparticles with a high grafting density, indicating successfully grafting of the AA and MAA onto the surface of fumed silica. Grafting amounts of the polymers onto the fumed silica nanoparticles surface were calculated from TGA thermograms to be 31.6 % and 52.7 % for the AA and MAA, respectively. DLS and SEM results showed average particle diameter less than 100 nm for the PAA-g-FSN and PMAA-g-FSN hybrid nanoparticles.