Heat-induced morphological transformation of gold nanodumbbells in ionic surfactant solutions

Highlights: • We report a simple method to modify the aspect ratio of gold nanorods (NRs). • Gold nanodumbbells (NDs) could be synthesized in the presence of gold NR seeds. • The blue-shift of the longitudinal SPR band of gold NDs occurred at 75 °C. • New gold NRs with a shortened aspect ratio are formed after heating gold NDs. • The same results are found in the solution of cationic or anionic surfactant at different temp. The thermal stability of gold nanodumbbells (NDs) is studied in aqueous solution of ionic surfactants. It is found in aqueous solution of cetyltrimethylammonium bromide that the blue-shift of longitudinal surface plasmon resonance band of gold NDs occurs at 75 °C and the new gold nanorods (NRs) with shortened aspect ratio are formed at the same time. The aspect ratio of the generated gold NRs gradually decreases and finally approaches ∼1.7 after repeated processing. Similarly, the same results are also obtained in aqueous solution of sodium dodecyl sulfate at room temperature. Mechanism is proposed for the shape transformation of gold NDs.