Experimental Investigation of the Stability of Electrospray Cone-Jet Formation for Weakly Viscoelastic Fluids

In recent years, the scientific community has focused on understanding the physical mechanisms responsible for the generation of a stable electrospray cone-jet mode for Newtonian fluids [1] with an electrical conductivity of the order of 10 S/m and developing scaling laws to predict the jet diameter and the minimum flow rate required to create a stable electrospray [1]. Moreover, numerical simulations were carried out to predict stable electrospray formation for weakly viscoelastic fluids and how viscoelasticity affects the process [2]. In this work, we experimentally studied the formation of stable electrospray for several viscoelastic fluids with electrical conductivities below 10 S/m. These fluids consist of a polymer solution of 2.5% w/v of ethyl cellulose dissolved in toluene or in 90/10% v/v of toluene/ethanol and a suspension containing 3.0% w/w of 2D nanoparticles dispersed within. The nanoparticles used are hexagonal boron nitride (hBN), molybdenum disulfide (MoS). Our experimental findings reveal the successful establishment of a stable electrospray cone-jet mode for all tested fluids. We demonstrate the feasibility of generating a stable electrospray with a jet diameter below 50 μm at a flow rate of 5 ml/h and an electric field strength of 1.8 kV/mm. We show the dependence of the jet diameter on the flow rate.