"Semi-decoration" of silica particles(so-called Janus particles) with polydimethylamino ethylmethacrylate(PDMAEMA) grafts was carried out using surface-initiated atom transfer radical polymerization(SI-ATRP) based on Pickering emulsion template.ATRP initiator-immobilized silica particles assembled at the interfaces of paraffin oil-in-water emulsions and an ultimately stable Pickering emulsion was formed.SI-ATRP of water-soluble monomer DMAEMA was conducted in the water phase of the Pickering emulsion from the outer side of silica nanoparticles.Janus particles were obtained.Ag nanoparticles absorbed onto the PDMAEMA region of silica particles could be observed by transmission electron microscopy(TEM) image which indicated that Janus particles were successfully prepared.The semi-decoration by SI-ATRP based on Pickering emulsion technique offers a new route to designing Janus particles.
