In situ Preparation of Ag/Au Nanoparticle Bilayer via Layer-by-Layer Assembly in Spherical Polyelectrolyte Brushes

摘要

Spherical polyelectrolyte brushes (SPB) consist of linear polyelectrolyte chains which are grafted densely onto solid spherical core. Due to the strengthened Donnan Effect, the concentration of counter-ions in SPB can keep relatively invariant [1], which makes it advantageous for use as nanoreactors. Metal nanoparticles like Au, Ni, Pt et al. [2-4], which have high catalytic activity, can be prepared with narrow size distribution and well stability using these nanoreactors. The fabrication of multilayers by alternating adsorption of polyanions and polycations has been studied for decades [5]. The driving force of Layer-by-layer deposition is electrostatic attraction between opposite charge polymers which made the multilayer build-up. Nowadays, layer-by-layer deposition was used in many aspects, for example, preparing micro-capsule [6], multilayer catalyst and proteins. In this paper, both gold nano-particles (Au-NPs) and silver nano- particles (Ag-NPs) are prepared via layer-by-layer adsorption of polyanions immobilized silver nano-particles (PLys-Ag) onto cationic spherical polyelectrolyte brushes, in which Au-NPs are grafted onto the shell of polycations PAEMH (Figure 1). The charge change of system is determined by zeta potential to identify whether polyanions PLys successfully coated on SPB. Their microstructure is observed by transmission electron microscope (TEM).