The attractive optical properties of metallic nanoparticles include the optically interesting but surprisingly not well understood dichroic effect, defined in this research as when particle colloids display different colours in...

Two reducing agents can be used simultaneously to control nanoparticle shape and produce anisotropic nanoparticles without a structure directing agent.

Gold nanoparticles make an appealing candidate as textile colorants due to the range of attractive colors they can produce and their exceptional stability compared to organic dyes. However, ensuring a strong interaction between the fabric and the nanoparticles remains a challenge. We have investigated the use of commercial reactive dyes to (1) reduce gold ions and form nanoparticles and (2) form a chemical link between the nanoparticles and wool fibers. For the first time, gold nanoparticles have been produced using organic reactive dyes as reducing agents. As part of this process, the chromophore of the dye has been chemically altered such that it does not contribute any color, and the red shades displayed result entirely from gold nanoparticles. These nanoparticles have then been tested for their ability to dye wool yarn samples. Careful analysis has indicated that a weak bond has formed between the particles and the fibers due to degradation of the dye structure during reduction. The mechanism of degradation has been studied, providing insight into the type of chemical structure that could be used in the future to achieve wash-fast gold nanoparticle textiles.