<i>Modelling Nanowire Formation in Electrospray Deposition of Polymeric Droplets </i>

The formation of nanowire forests was recently reported for the first time in electrospray deposition (ESD) of methylcellulose solutions. This novel morphology provides new opportunities for nanomaterial processing. The atypical nanowire geometry is a result of complex interplay among electrostatic interaction, solvent evaporation and polymer rheology. We conducted computer simulations to uncover the physics underpinning the morphological evolution of a highly charged polymeric droplets in ESD. We utilize electrostatic dissipative particle dynamics (EDPD) to simulate a model system that captures electrostatic interaction, evaporation, and polymer dynamics. We explored droplet morphological development under different evaporation conditions, which results in distinct modes of viscosity evolution. Our results show that the nanowire formation is a result of spinodal phase separation between polymers and solvents that homogeneously increases viscosity within the droplet. In contrast, a steep viscosity gradient formed leads to a bead-strings morphology. The coupling between electrostatically-driven deformation and evaporation-driven viscosity change in polymeric droplets can result in new and beautiful morphological evolution.