The intense plasmon absorption bands of gold nanorods (GNRs) with peak extinction coefficients up to 6.4×109 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.

中文翻译：

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基于二氧化硅涂层金纳米棒的颜料：合成、着色强度、功能化、挤出、热稳定性和颜色演变

金纳米棒 (GNRs) 的强等离子体吸收带具有高达 6.4×109 M-1 cm-1 的峰值消光系数以及它们预期的高稳定性，使 GNRs 成为大块材料着色的有希望的候选者。GNRs在可见光区的积分吸收与商业有机颜料的比较表明，GNRs的着色强度高出4-8倍。为了提高其稳定性，GNRs被封装在15 nm左右的二氧化硅壳中使用优化的 Stöber 方法的厚度。二氧化硅表面用十八烷基硅烷改性，使其分散在非极性介质中。不同的塑料成功地用少量的裸露和功能化的 GNRs@SiO2 着色。这些棒使用挤出均匀分散。在挤压过程中，二氧化硅壳在高温下有效地稳定了棒的形状。令人惊讶的是，由于介孔二氧化硅壳中的折射率降低，观察到棒颜色的轻微改变。然而，这种效果在功能化后受到很大限制。