Effect of the hydrophobic chain length of a surfactant on controlling the morphology of gold crystals

In this paper, a set of tree-type multiple-head surfactants, bis.amidoethyl-carbamoylethyl) X-amine (CxN3, x = 12, 14, 16 and 18) have been used as reducing agents and as template molecules to study the effect of their chain length on the morphologies of gold crystals. It is proven that these four surfactants had obvious different abilities in controlling the morphology of the gold crystals and that surfactant molecules with a longer hydrophobic tail would generate better shaped gold plates. According to our results, many gold crystals have been successfully fabricated such as cracked potato chip-like plates, nano-desert roses, and durian-like microspheres and all of these gold crystals greatly improved the surface enhanced Raman scattering (SERS) of melamine molecules, which suggested that these gold crystals have great potential in applications such as pollution detection.