The synthesis of polymer-matrix-compatible amphiphilic gold (Au) nano-particles with well-defined triblock polymer poly[2-(N,N-dimethylamino)ethyl methacrylate]-b-poly(methyl methacrylate)-b-poly[2-(N,N-dimethylamino)ethyl methaerylate] and diblock polymers poly(methyl methacrylate)-b-poly[2-(NN-dimethylamino)ethyl methacrylate], polystyrene-b-poly[2-(N,N-dimethylamino)ethyl methacrylate], and poly (t-butyl methacrylate)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate in water and in aqueous tetrahydrofuran (tetrahydrofuran/H2O = 20:1 v/v) at room temperature is reported. All these amphiphilic block copolymers were synthesized with atom transfer radical polymerization. The variations of the position of the plasmon resonance band and the core diameter of such block copolymer functionalized An particles with the variation of the surface functionality, solvent, and molecular weight of the hydrophobic and hydrophilic parts of the block copolymers were systematically studied. Different types of polymer-Au nanocomposite films [poly(methyl methacrylate)-Au, poly(t-butyl methacrylate)-Au, polystyrene-Au, poly(vinyl alcohol)-Au, and poly(vinyl pyrrolidone)-Au] were prepared through the blending of appropriate functionalized Au nanoparticles with the respective polymer matrices {e.g., blending poly[2-(N,N-dimethylamino)ethyl methaerylate]-b-poly(methyl methacrylate)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] stabilized Au with the poly(methyl methacrylate)matrix only}. The compatibility of specific block copolymer modified Au nanoparticles with a specific homopolymer matrix was determined by a combination of ultraviolet-visible spectroscopy, transmission electron microscopy, and differential scanning calorimetry analyses. The facile formation of polymer-Au nanocomposites with a specific block copolymer stabilized Au particle was attributed to the good compatibility of block copolymer coated Au particles with a specific polymer matrix. (c) 2006 Wiley Periodicals, Inc.