Using hydroxy carboxylate to synthesize gold nanoparticles in heating and photochemical reactions and their application in textile colouration

Coloured metallic nanoparticles (NPs), which have colour that is related to the size of the particle, can be synthesized by a variety of different methods. The ultraviolet (UV) light stability of metallic nanoparticles make them an attractive alternative for colouring textiles that may be exposed to high levels of UV light. In this research, gold NPs were synthesized with citrate, malate and tartrate ligands by heating and photochemistry. Extinction spectroscopy was used to quantify NPs formation rate, and transmission electron microscopy (TEM) was employed to characterise morphologies of NPs. In both formation paths, the ligand acted simultaneously as a reducing and a stabilizing agent for the NPs. Tartrate presented the highest photochemical reaction rate and the NPs were spherical or oval in shape. The products obtained by heating with citrate were the most uniform nanospheres in this study. Samples prepared with tartrate were the largest of the three ligands regardless of the synthesis path. The synthesized NPs were successfully used to colour wool fabric, silk and nylon fibres.