Preparation of polymer core–shell particles supporting gold nanoparticles

Abstract

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-PDMAEMA x/ 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-PDMAEMA x/ y /Au z hybrid particles were successfully obtained by loading with hydrogen tetrachloroaurate (HAuCl 4) 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 HAuCl 4 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 HAuCl 4 of 100 mM.