Gold Nanoparticles: A Novel Dye for Synthetic Fabrics
Fabric has always been prominent throughout history. In the last 70 years new synthetic fabrics have been developed which mimic the natural fibres but have increased strength, durability and stretchability. Common fibres include Polyester, Nylon and Lycra(R). These fibres can be blended to incorporate the properties of both the individual fibre types. Gold nanoparticles have been found to give the stable deep red colour found in stained glass but the science was not understood until the quantum mechanical work of Mie in 1908 on the interaction of electromagnetic radiation (visible light) with fine particles of matter. It is proposed that gold nanoparticles can be used as stable colourants bound to synthetic fibres and other textiles due to its chemical unreactivity. The most common formation method is the use of a reductant such as poly(ethylene imine), sodium citrate or tannic acid. This thesis reports the research and development of new, novel hybrid materials created by combining the interesting properties of both the synthetic fabrics and gold nanoparticles. Twenty five different methods (broken down into four general categories - pre-made colloids, in-situ reduction, use of external reductant after uptake of gold solution and growth of seed particles) were attempted resulting in fabrics that were a variety of shades and colours including pink, purple, tan and gold. The synthetic fabric-gold nanoparticle hybrid samples were analysed by scanning electron microscopy, energy dispersive spectroscopy, infrared spectroscopy, ultraviolet/visible reflectance spectroscopy, x-ray photoelectron spectroscopy, fluorescence spectroscopy and ColourQuest measurements. A sample was also subjected to industry standard "abrasion" and colourfastness tests in which it gained the highest mark possible, showing no staining of other fabrics under dry rub conditions. Atomic absorption measurements were performed on solutions after the fabric was removed in order to confirm the amount of gold uptake by the fabric samples. Analysis showed that a range of nanoparticle sizes and shapes were produced which influenced the visual colour of the fabric. The purple samples produced are caused by small particles (<100nm) that have aggregated together. Samples that appear tan or gold in colour have mainly large particles (>500nm) that are either made up of small spheres fused together or are large plates (trigonal, hexagonal); therefore, Mie's laws do not appear to apply. Light coloured samples generally have a few small particles (<100nm) that are spaced out over the fibre surface.