TY - JOUR AU - Gautier, Cyrille AU - Cunningham, Alastair AU - Si-Ahmed, Lynda AU - Robert, Gilles AU - Bürgi, Thomas TI - Pigments based on silica-coated gold nanorods: Synthesis, colouring strength, functionalisation, extrusion, thermal stability and colour evolution PY - 2010 JF - Gold Bulletin JA - Gold Bull. SN - 0017-1557 VL - 43 IS - 2 SP - 94 EP - 104 L1 - http://www.goldbulletin.org/assets/file/goldbulletin/downloads/Gautier_GB_2_43.pdf KW - gold KW - silica KW - nanorods KW - thermal stability KW - porosity KW - coloring strength N2 - The intense plasmon absorption bands of gold nanorods (GNRs) with peak extinction coefficients up to 6.4 x 109 M-1 cm-1 as well as their expected high stability make GNRs promising candidates for the colouration of bulk materials. The comparison of the integrated absorption in the visible region of GNRs with those of commercial organic pigments shows that the colouring strength of GNRs is 4 to 8 times higher. In order to improve their stability, GNRs were encapsulated in a silica shell of around 15 nm thickness using an optimized Stöber method. The silica surface was modified with octadecylsilane to enable their dispersion in non-polar media. Different plastics were successfully coloured with a tiny quantity of bare and functionalised GNRs@SiO2. These rods were homogeneously dispersed using extrusion. The shape of the rods was effectively stabilised by the silica shell at high temperature during the extrusion process. Surprisingly, a slight modification of the rods colour was observed due to a decrease of the refractive index in the mesoporous silica shell. However, this effect is greatly limited after the functionalisation. ID - 1187 ER -