In situ synthesis of the Ag/poly(4-vinylpyridine)-block-polystyrene composite nanoparticles by dispersion RAFT polymerization1

Metal/block-copolymer composite nanoparticles have been attracting considerable interest and are usually prepared by incorporating metal nanoparticles or metal ions into pre-prepared block copolymer nanoparticles. Herein, a new method of one-pot synthesis of the colloid-like metal/block-copolymer nanocomposites of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) and Ag nanoparticles by dispersion RAFT polymerization is proposed. This method employs the chelate polymer of poly(4-vinylpyridine) trithiocarbonate (P4VP-TTC) as both a macro-RAFT agent for dispersion RAFT polymerization and a stabilizer for Ag nanoparticles, and it affords a convenient synthesis of the Ag/P4VP-b-PS composite nanoparticles. Ag nanoparticles are uniformly embedded in the P4VP-b-PS nanoparticles to result into Ag/P4VP-b-PS composited nanoparticles. It is found that the size of the Ag/P4VP-b-PS composite nanoparticles increases either with the degree of polymerization of the polystyrene block or with the Ag fraction in the nanocomposites. This dispersion RAFT polymerization in the presence of a macro-RAFT agent stabilized metal nanoparticles is believed to be an efficient method to synthesize concentrated metal/block-copolymer nanocomposites.