Phase transfer of aqueous CdS nanoparticles by coordination with octadecanethiol molecules present in nonpolar organic solvents

Abstract

The transfer of CdS nanoparticles of dimensions 60 Å synthesized in an aqueous environment into petroleum ether (pet ether) by coordination of the nanoparticles with octadecanethiol (ODT) molecules present in the organic phase is described. The phase transfer of the CdS nanoparticles into pet ether occurs extremely rapidly during vigorous stirring of the biphasic mixture (CdS-in-water/ODT-in-pet ether). Hydrophobization of the CdS nanoparticles due to surface coordination of ODT facilitates the phase transfer process. The hydrophobized CdS nanoparticles may be precipitated and redispersed in different nonpolar organic solvents without an apparent distortion in the particle size distribution. Close-packed CdS nanoparticle thin films were formed by immersion of suitable substrates in the organic solutions and evaporation of the organic component. The CdS nanoparticles have been characterized at different stages of the synthesis procedure using UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetry, X-ray photoemission spectroscopy (XPS), and contact angle measurements.