Controllable assembly of two types of metal nanoparticles onto block copolymer nanospheres with ordered spatial distribution

In this study, we report a novel method to assemble two types of metal nanoparticles onto poly(styrene-b-2-vinylpyridine) (PS-P2VP) block copolymer nanospheres with ordered spatial distribution. As a first step, core-shell metal-polymer particles have been fabricated, which consist of dodecanethiol (DT)-Au aggregation as core and PS-P2VP block copolymer as shell. Such core-shell particles have been obtained by swelling the DT-Au contained PS-P2VP nanoblocks, which are derived from Rayleigh instability of DT-Au@PS-P2VP nanotubes inside the cylindrical nanopores of anodic aluminum oxide (AAO) membranes. The core size and shell thickness of the particles can be tuned by the weight ratio of PS-P2VP to DT-Au content. An increase of the DT-Au content results in an increase of the DT-Au core size, combined with a red shift of the surface plasmon absorption peak in the UV-vis spectra. Such core-shell particles have been further decorated with Pd nanoparticles on the shell due to the microphase separation of the PS-P2VP, which shows efficient catalytic activity for the reduction of 4-nitrophenol by NaBH₄. Thus, the Au and Pd nanoparticles have been selectively assembled onto the PS-P2VP particles with ordered spatial distribution, leading to composite particles with multiple functions from both metal nanoparticles.