Facile and controllable incorporation of gold nanoparticles within one-dimensional self-assemblies of hyperbranched polymers

Abstract

Using a mono-pyrene terminated hyperbranched polyglycidol (mPTHP) as a building block, one-dimensional (1D) mPTHP and mPTHP/gold nanoparticle (Au NP) nanostructures are fabricated in the presence of HAuCl₄. By simply mixing mPTHP and different concentrations of aqueous HAuCl₄ solution at room temperature, mPTHP nanofibers and nanotubes are obtained through Au(III) ion induced self-assembly processes. Upon elevating the reaction temperature from room temperature to 60 °C, Au NPs are in situ generated within 1D mPTHP assemblies via an analogous “polyol process”, forming mPTHP/Au NP hybrid nanofibers and nanotubes. Careful control of the HAuCl₄ concentration enables in situ generated Au NPs to be either distributed along the center-line of nanofibers or symmetrically aligned into a double-line along the nanofibers and the inner surface of nanotubes. Further investigation reveals that the involvement of a small amount of NaBr in the reaction system of mPTHP and different amounts of HAuCl₄ results in the formation of pseudo-nanotubes decorated with double-lined Au NP chains along their inner surfaces. Moreover, the size of Au NPs can be effectively tuned in terms of HAuCl₄ concentration. All 1D mPTHP and mPTHP/Au NP nanostructures described in our current work are achieved through one-pot aqueous reactions in the absence of any additional reducing agents, surfactants and organic solvents, so that they are facile, green and low-cost strategies. To the best of our knowledge, this is the first example to synthesize 1D hyperbranched polymer/metal NP hybrid nanostructures with controllable spatial distribution of NPs using such a facile and green protocol.