Rational control of anisotropic nanocomposites for engineered nanocatives and SERS application

A variety of nanocomposites between metallic nanoparticles and polymers were produced. The attachment pattern of polymer micelles on the metal nanostructures evolved from the full coverage to partially engulfing, i. e. Janus (two-faced) nanoparticles, through tuning the ligand combinations. The basic principle for this achievement is that the surface feature is dictated by competitive chemisorption of hydrophobic and hydrophilic ligands forming segregated patches on the nanostructures, which results in directional self-assembly of amphiphilic diblock copolymer on the hydrophobic ligand coated surface, while leaving the hydrophilic ligand modified surface exposed to the aqueous solution. The generality of this strategy has been demonstrated by creating a broad range of nanocomposties with different metallic cores, different ligand combinations and various amphiphilic diblock copolymers. Also, we further extend this concept for the creation of hollow polymeric structures with openings (at nanoscale), the investigation of the surface-enhanced Raman scattering site distributions on nanospheres and nanorods, and the controlled organization of the nanoparticles into dimers or oligomers.