Phase equilibria and charge fractionation in polydisperse polyelectrolyte solutions

TL;DR

This paper predicts a novel phase separation in polydisperse polyelectrolyte solutions caused by differences in ionization, leading to charge fractionation and spatial separation before precipitation, with implications for biological systems.

Contribution

It introduces a thermodynamic model predicting charge fractionation and phase separation in polydisperse polyelectrolyte solutions based on ionization differences.

Findings

Small ionization differences cause early phase separation.

Charge fractionation occurs prior to precipitation.

Implications for biological processes are discussed.

Abstract

A new type of phase separation in the polyelectrolyte solutions consisting of several types of charged macromolecules differing in their degree of ionization is predicted via a general thermodynamic consideration. We show that even a small difference in the degree of ionization of otherwise equivalent components results in their spatial separation occurring upon decreasing the temperature much earlier than precipitation of the components from the solution. Some implications of charge fractionation in biological processes are discussed.