Fabrication of gold nanoparticle-polymer composite particles with raspberry, core-shell and amorphous morphologies at room temperature via electrostatic interactions and diffusion

Composite particles with varying morphologies composed of gold nanoparticles (Au NPs) and polymers were fabricated based on a combination of electrostatic interactions between the polymer particles and Au NPs and diffusion processes. The positively charged polymer particles were prepared from amino-terminated polystyrene (PS-NH₂) and amino-terminated 1,2-polybutadiene (PB-NH₂). Adsorption of citrate-stabilized Au NPs resulted in three different distribution states of Au NPs in the polymer particles, depending on the glass transition temperature (T_g) and molecular weight of the polymer. The adsorption of Au NPs onto PS-NH₂ particles produced raspberry-like composite particle morphologies, while the NPs instead diffused into the PB-NH₂ particles, since the T _g of PB-NH₂ is below room temperature. The diffusion of Au NPs could be controlled by varying the molecular weight of the PB-NH ₂ and the diameter of the NPs, and both core-shell and amorphous distributions were successfully achieved.