Effect of Solvent Quality on the Phase Behavior of Polyelectrolyte Complexes

06 May 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The role of polyelectrolyte-solvent interactions, among other non-Coulomb interactions, in dictating the thermodynamics and kinetics of polyelectrolyte complexation is prominent, yet sparingly studied. In this article, we present systematic comparisons of the binodal phase behavior of polyelectrolyte complexes (PECs) comprising polyelectrolytes with varying quality of backbone-solvent interactions. Experimental phase diagrams of polyelectrolyte complexes with either a peptide or an aliphatic backbone highlight the influence of backbone chemistry on the composition of complexes and their salt resistance. Corresponding theoretical phase diagrams, obtained from a framework combining the random phase approximation and Flory- Huggins approach, reveal a transition from closed phase boundaries with confined two-phase regions for PECs in good solvents to open phase boundaries, wherein two-phase systems are predicted to exist even at very high salt concentrations, for PECs in poor solvents. These predictions compare fittingly with experimental observations of low salt resistance (~1 M NaCl) of PECs comprising hydrophilic polyelectrolytes and persistence of complexes, stabilized by short-range hydrophobic interactions, even at very high salt concentrations (~6 M NaCl) for PECs comprising hydrophobic polyelectrolytes.


Polyelectrolyte Complexation Polyelectrolyte complexes
Phase Behavior
RPA Theory

Supplementary materials

SI Li et al PEC Phase Behavior Solvent Quality submitted


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.