Encapsulation of Au Nanoparticles by Poly(4-Vinylpyridine)-Block-Polystyrene-Block-Poly(4-Vinylpyridine) for Controlled Chain Assembly

We report a facile method to encapsulate Au nanoparticles (NPs) in an amphiphilic ABA triblock copolymer, poly(4-vinylpyridine)-block-polystyrene-block-poly(4-vinylpyridine) (P4VP-b-PS-b-P4VP), forming Au@P4VP-b-PS-b-P4VP core–shell nanostructures. On the basis of the hydrophobically funcationalized Au surface, we propose that the P4VP-b-PS-b-P4VP is folded into a U shape, so that the hydrophobic PS block attach to the Au surface and the hydrophilic P4VP blocks are dissolved in the solution facing outwards. As the polymer micelles transform from spheres to cylinders and vesicles, the embedded Au NPs are brought along in the process and end up in the complex polymer nanostructures. Driven by the tendency of the polymer to form cylindrical micelles, the positively charged core–shell NPs can assemble into chains, where the method was only demonstrated previously exploiting the negatively charged amphiphilic polystyrene-block-poly(acrylic acid) shells.