Gold nanorods with different aspect ratios were synthesized by the photochemical reduction method in H₂O-DMF-acetone medium containing HAuCl₄ and cetyltrimethyl ammonium chloride (CTMAC), by means of forming CTMAC micelle as template and acetone as photosensitizer. The transformation from spherical to rodlike micelle was realized by changing the ratio of DMF∶H₂O (V/V) to turn the polarity of the medium and increasing micelle aggregation number, as a result, a colloidal solution predominated by rodlike gold nanoparticles was obtained. The influence of the concentration of HAuCl₄ and CTMAC as well as irradiation time on the growth of nanoparticle self-organization was investigated. Under optimal conditions, gold nanorods with a diameter of 20 to 22 nm and a length of 0.5 to 3 μm were synthesized. The mechanisms of the photochemical reaction and gold nanoparticle self-organization in rodshaped micelle were discussed in detail.

Key words: photochemical method, preparation, cationic surfactant, micelle template, gold nanorod, self-organization, mechanism