Stabilization of Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles.

The colloidal suspension containing a high concentration of metallic nanoparticles (NPs) find potential applications in flexible electronic printing, nanofluids, healthcare, and antifouling coating etc. Here, we demonstrate a generic, easily scalable, simple and contamination free cryogenic temperature grinding method, which can effectively be used to prepare pristine NPs and can be stabilized in polar liquids in a high-concentrations. These surfactant free pristine nanoparticles have been found to remain dispersed in different polar liquids (CH3OH, C2H5OH, Glycol etc.) for weeks. The long term stability of the nanoparticles in these liquids has been investigated using zeta potentials, In-situ FTIR spectroscopy indicating electrostatic stabilization for ultra pure, surfactant free NPs. Furthermore, stabilization of the NPs has been probed detailed calculation using DLVO theory as well as atomistic molecular dynamic simulation (MD). Experimental measurements along with theoretical calculation categorically indicate the electrostatic energy helping these nanoparticles to be stabilized in a polar liquid.