Charging, clustering, and fragmentation of nanoparticles and macromolecules in electrohydrodynamic atomization

Electrohydrodynamic atomization (EHDA) of solutions and particle suspensions produces highly charged droplets and, after complete droplet evaporation, highly charged aerosol particles. Highly charged aerosol particles and macromolecules are of great interest and utility in materials' processing and analytical chemistry. However, little is known about the influence of the EHDA process parameters on the properties of the produced aerosol particles. Fundamental studies of highly charged droplets, produced by electrohydrodynamic atomization of nanoparticle and macromolecule suspensions, were performed. The effects of produced droplet size, droplet evaporation, and droplet charge loss dynamics on the size and charge of aerosol nanoparticles and macromolecules were determined. The size distribution functions of polymer particles produced by EHDA of polymer solutions were determined experimentally and shown to be predictable based on scaling laws for droplet size in EHDA. Production of nearly monodisperse sub-10 nm iron oxide aerosol particles by EHDA and heating of the iron storage protein, ferritin, was demonstrated. Isolated aerosol virus particles were produced by EHDA and detected by electrical mobility spectrometry. It was found that the EHDA process can fragment viruses at non-covalent interfaces if the produced droplets are of similar size to the viruses. The production of porous particulate films by EHDA of concentrated nanosuspensions was studied through experiments and numerical simulations. Control over film thickness, porosity, and surface roughness by controlling the EHDA liquid flowrate, electrical conductivity and suspension concentration was shown. A Monte-Carlo based technique was developed to determine the efficiency of ionization by EHDA for isolated macromolecules and nanoparticles, and the kinetics of ion emission from highly charged nanodroplets were used to develop a model to predict the number of charges on native state proteins. Submicrometer droplet charge loss by Coulombic fission and the charging of submicrometer particles in EHDA were also examined experimentally. The studies described in this dissertation provide a fundamental framework for future studies electrohydrodynamic atomization.