Structure of Liquid Coacervates formed by Oppositely Charged Polyelectrolytes.

Published

Journal Article

We develop a scaling theory and perform molecular dynamic simulations of weakly interacting coacervates with electrostatic interaction energy per charge less than thermal energy kT. Such liquid coacervates formed by oppositely charged polyelectrolytes can be asymmetric in charge density and number of charges per chain. We predict that these coacervates form interpenetrating solutions with two correlation lengths and two qualitatively different types of conformations of polyelectrolytes with lower and higher charge densities, which are analogous to chain conformations in quasi-neutral and in polyelectrolyte solutions, respectively. Weaker charged chains are attracted to and adsorbed on stronger charged chains forming a screening "coat" around the stronger charged polyelectrolytes. Salt added at lower concentrations screens the repulsion between stronger charged chains, thereby reducing the thickness of the screening coat and resulting in the non-zero net polymer charge in the coacervate. At higher salt concentrations salt screens the attraction between oppositely charged chains, decreasing the coacervate concentration and its polymeric charge density. Thus, we predict a non-monotonic salt concentration dependence of polymeric charge density for asymmetric coacervates. Phase diagram for a mixture of oppositely charged polyelectrolytes at various compositions is proposed for different salt concentrations.

Full Text

Duke Authors

Cited Authors

  • Rubinstein, M; Liao, Q; Panyukov, S

Published Date

  • December 2018

Published In

Volume / Issue

  • 51 / 23

Start / End Page

  • 9572 - 9588

PubMed ID

  • 30853717

Pubmed Central ID

  • 30853717

Electronic International Standard Serial Number (EISSN)

  • 1520-5835

International Standard Serial Number (ISSN)

  • 0024-9297

Digital Object Identifier (DOI)

  • 10.1021/acs.macromol.8b02059

Language

  • eng