Deposition of gold nanoparticles on mica modified by poly(allylamine hydrochloride) monolayers

Abstract

Bulk characteristics and deposition of gold nanoparticles on mica modified by (PAH) was studied by UV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and atomic force microscopy (AFM). The size of gold nanoparticles (AuNPs) was 15nm as determined by TEM and AFM. The electrophoretic mobilities and electrokinetic charge of particles were quantitatively evaluated for a broad range of pH and ionic strength. Using Henry's model, it was calculated that the zeta potential of particles varied between −50mV and −80mV for pH 2 and pH 11, respectively (at 10−2M of NaCl). Measurements of nanoparticle deposition kinetics were performed under diffusion-controlled transport conditions using AFM and SEM imaging of particle monolayers. The influence of the bulk suspension concentration was systematically studied. Additionally, the maximum coverage of particle monolayers, which monotonically increased with ionic strength, was determined by SEM. The obtained data were in agreement with theoretical predictions derived from the random sequential adsorption (RSA) model. It was also confirmed that by varying the bulk suspension concentration and ionic strength one can prepare homogeneous gold particle monolayers of controlled coverage.