| Abstract
| - Surface-initiated atom-transfer radical polymerization (SI-ATRP) of 4-vinylpyridine occurring on gold nanoparticles results in the formation of a core−shell Au@PVP nanostructure. Such environmentally responsive nanocomposites with effective coordinating pyridyl segments provide a smart supporter or carrier to transition metal ions and nanoparticles to construct novel bimetallic nanocomposites, especially in catalyst applications.
- Novel nanocomposites of gold nanoparticle and poly(4-vinylpyridine) (Au@PVP) were fabricatedthrough surface-initiated atom-transfer radical polymerization (SI-ATRP) at ambient conditions. The citrate-stabilized gold nanoparticles were first modified by a disulfide initiator for ATRP initiation, and thefollowing polymerization of 4-vinylpyridine (4VP) occurred on the surface of gold particles. The assembledAu@PVP nanocomposites are pH-responsive because of the pyridyl groups, which are facially protonatedand positively charged. At low pH (<3.2), the polymer chains attached on gold nanoparticles are expandedby electrostatic forces, and the polymer layer is loosely swelled; hence, the Au@PVP composite particledisplays a comatulid-like nanostructure in 3-D AFM images. However, at a relatively high pH (>3.2),the polymer chains shrink and wrap around the gold particle surface, which results in the aggregation ofgold nanoparticles with a thin shrunken polymer layer under TEM observation. Such assembled Au@PVPnanocomposites as a smart supporter can entrap transition metal ions by their efficient coordinatingsegments, and subsequently, the metal ions can be reduced in situ to construct novel bimetallicnanocomposites, which are regarded as intelligent catalysts with environmental stimuli activity.
|
