Preparation of polymer core–shell particles supporting gold nanoparticles

The organic/inorganic composites were fabricated by catalytic reduction of tetrachloroaurate ions in poly[2-(N,N-dimethylamino)ethyl methacrylate] shell layers on polystyrene core particles. The core–shell particles were prepared by emulsifier-free emulsion polymerization of styrene (St) with 2-chloropropionyloxyethyl methacrylate (CPEM) using potassium persulfate as an initiator, followed by surface-initiated activator generated electron transfer-atom transfer radical polymerization (AGET-ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) on core particles dispersed in aqueous media. The concentration effect of both DMAEMA (x) and copper complex (y) on a shell thickness of P(St-CPEM)-g-PDMAEMAx/y core–shell particles was investigated by light scattering technique. The amount of grafted DMAEMA units with respect to (wrt) St was determined by 1H NMR spectra measurement. The P(St-CPEM)-g-PDMAEMAx/y/Auz hybrid particles were successfully obtained by loading with hydrogen tetrachloroaurate (HAuCl4) into the P(St-CPEM)-g-PDMAEMA aqueous dispersions. The particle size and shape of gold nanoparticles (NPs) generated by catalytic reduction in the poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA) shell layers were evaluated by both UV/vis absorption spectra measurement and TEM observation. The size and the number of gold NPs increased with increasing HAuCl4 concentration (z) below 75 mM. Interestingly, 60–80 nm sized, trigonal or polygonal, plate-like gold NPs were generated in the PDMAEMA shell by adding HAuCl4 of 100 mM.