Use of repeated phase transfer for preparation of thiol coated copper organosols at higher particle loading

This work aims at preparing thiol coated copper organosols of small size and high particle loading by using phase transfer of pre-formed particles. HCl mediated and ethanol mediated phase transfer protocols have been successfully used to transfer particles from charge stabilized and citrate stabilized hydrosols of various concentrations. To increase the concentration of particles in the organic phase a new strategy based on repeated phase transfer has been successfully introduced. It has been shown that up to a certain concentration of hydrosol, the particle size is preserved during single and repeated phase transfer. If the concentration of hydrosol is higher than this threshold, elongated structures containing 2–3 primary particles are formed in the organosol. Citrate stabilized hydrosol has also been successfully transferred using HCl mediated and ethanol mediated protocols. Stability and oxidation resistance of all the sols have been thoroughly studied. The most stable, concentrated organosol containing 2–4 nm particles is produced by repeated phase transfer of charge stabilized dilute hydrosol.