Electrostatic effects in macromolecular and interfacial systems

Abstract

In this talk, I discuss two electrostatic effects that have profound effects in macromol. and interfacial systems and yet have not been much appreciated in the main literature on electrolytes or polyelectrolytes. The first effect is the Born solvation energy or more generally the self-energy of salt ions. The preference of an ion to be solvated by the more polarizable component in a liq. mixt. creates a significant driving force for phase sepn. and is responsible for the nonuniform salt concn. and charge sepn. near an interface. The preferential solvation effect is used to explain the dramatic increase in the order-disorder transition temp. of Polyethylene Oxide-Polystyrene diblock copolymer upon the addn. of small amts. of lithium salts. I also present a simple theory for explaining the long-standing Jones-Ray and ion size effects in the interfacial tension for electrolyte solns. The second effect is the Donnan potential effect in biol. systems. The presence of mostly neg. charged macromols. in the cellular milieu generates a substantial neg. potential relative to a monovalent salt soln. I present a theory that argues that this Donnan potential explains the prevalence of neg. overcharged RNA viruses in Nature.