Manifestations of Charge Induced Instability in Droplets Effected by Charged Macromolecules

Ion-release processes from droplets that contain excess charge are of central importance in determining the charge-state distributions of macromolecules in electrospray ionization methods. We develop an analytical theory to describe the mechanism of contiguous extrusion of a charged macromolecule from a droplet. We find that the universal parameter determining the system behavior is the ratio of solvation energy per unit length to the square of the ion charge density per unit length. Systems with the same value of the ratio will follow the same path in the course of droplet evaporation. The analytical model is compared with molecular simulations of charged polyethylene glycol macroion in aqueous droplets, and the results are in excellent agreement.