Surface modification of silica nanoparticles by grafting poly(methyl methacrylate) using atom transfer radical polymerisation with activators regenerated by electron transfer

The homopolymer poly(methyl methacrylate) (PMMA) shells were grafted onto the silica nanoparticle surfaces by iron(III)-mediated atom transfer radical polymerisation with activators regenerated by electron transfer (ARGET ATRP). The grafting process was carried out in two steps. First, the halogen-functional ATRP initiators were immobilised on the silica nanoparticle surfaces. Secondly, the polymerisation of methyl methacrylate was conducted on the surfaces of silica using FeCl₃ as the catalyst and ascorbic acid (VC) as the reducing agent in the presence of a limited amount of air. Well-defined polymer was grown from the silica surfaces to yield nanospheres composed of a silica core and a densely grafted outer PMMA shell.