Elongated copper nanoparticles coated with a zwitterionic surfactant

A sonochemical approach to the preparation of elongated copper nanoparticle s coated with a zwitterionic surfactant, cetyltrimethylammonium p-toluene s ulfonate (CTAPTS) is reported. A shape transition of the copper nanoparticl es is found to occur due to the presence of an organized medium, consisting of a cylindrical, interconnected network of threadlike micelles. Transmiss ion electron micrographs (TEM) show the presence of elongated copper nanopa rticles coated with the surfactant. UV-visible spectroscopic studies point to the elongation of the copper nanoparticles and to the adsorption of the CTAPTS on the surface of the copper nanoparticles, which is corroborated by IR and NMR spectral studies. A monolayer coating of the surfactant is form ed on the surface of the elongated copper nanoparticles. This is confirmed by comparing the weight loss obtained in thermogravimetric analysis with th at obtained theoretically.