Nanoparticle-loaded cylindrical micelles from nanopore extrusion of block copolymer spherical micelles.

Hybrid cylindrical micelles loaded with nanoparticles are fabricated via extrusion of spherical micelles in solution phase through small long cylindrical pores. Small gold nanoparticles (AuNPs) are pre-coated with thiol-terminated polystyrene and then further encapsulated in the core part of block copolymer spherical micelles by a precipitation method. By varying the starting mass ratio of AuNPs and the diblock copolymers polystyrene-b-polyisoprene (PS-b-PI) during the encapsulation, the AuNPs loading density along the cylindrical micelles can be controlled. The mechanism for this sphere-to-cylinder transition induced by extruding hybrid spherical micelles through small cylindrical nanopores is discussed. These findings provide a novel way to manufacture high-quality and functional polymeric nano-wires, which may open the door to new applications such as in plasmonic waveguides.