Synthesis
and Controlled Self-Assembly of UV-Responsive Gold Nanoparticles in
Block Copolymer Templates
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Abstract
We
demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized
by UV-responsive block copolymer ligands, poly(styrene)-<i>b</i>-poly(<i>o</i>-nitrobenzene acrylate)-SH (PS-<i>b</i>-PNBA-SH), followed by their targeted distribution within a lamellae-forming
poly(styrene)-<i>b</i>-poly(2-vinylpyridine) (PS-<i>b</i>-P2VP) block copolymer. The multilayer, micelle-like structure
of the GNPs consists of a gold core, an inner PNBA layer, and an outer
PS layer. The UV-sensitive PNBA segment can be deprotected into a
layer containing poly(acrylic acid) (PAA) when exposed to UV light
at 365 nm, which enables the simple and precise tuning of GNP surface
properties from hydrophobic to amphiphilic. The GNPs bearing ligands
of different chemical compositions were successfully and selectively
incorporated into the PS-<i>b</i>-P2VP block copolymer,
and UV light showed a profound influence on the spatial distributions
of GNPs. Prior to UV exposure, GNPs partition along the interfaces
of PS and P2VP domains, while the UV-treated GNPs are incorporated
into P2VP domains as a result of hydrogen bond interactions between
PAA on the gold surface and P2VP domains. This provides an easy way
of controlling the arrangement of nanoparticles in polymer matrices
by tailoring the nanoparticle surface using UV light