Controlled 2D Organization of Gold Nanoparticles in
Block Copolymer Monolayers
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Abstract
The organization of organic-capped
gold nanoparticles in PS-<i>b</i>-PMMA monolayers is investigated.
The preferred location
of the particles within the block copolymer template is found to depend
on both nanoparticle size and the length of the aliphatic capping
agent. In the case of relatively short ligands, the particles behave
as hard spheres and their incorporation in the polymer matrix can
be qualitatively rationalized by entropic considerations. Three distinct
arrangements are observed. Particles that are small, relative to the
radius of gyration of the host polymer, evenly disperse within the
PS domains, whereas the largest particles are considered form ordered,
island-like aggregates. Particles of intermediate size exhibit the
most striking arrangement, being relegated to the PS-PMMA interface
to form organized ring structures. The tendency of these particles
to assemble at the interface is sufficiently strong to force a modification
of the polymer morphology to accommodate the particles at higher loadings.
As the number of particles is increased, the circular PS-<i>b</i>-PMMA surface micelles elongate to form nanostrands