Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Crossover from Rouse to Reptation Dynamics in Salt-Free Polyelectrolyte Complex Coacervates

Journal Article · · ACS Macro Letters
Considerable interest in the dynamics and rheology of polyelectrolyte complex coacervates has been motivated by their industrial application as viscosity modifiers. A central question is the extent to which classical Rouse and reptation models can be applied to systems where electrostatic interactions play a critical role on the thermodynamics. By relying on molecular simulations, we present a direct analysis of the crossover from Rouse to reptation dynamics in salt-free complex coacervates as a function of chain length. This crossover shifts to shorter chain lengths as electrostatic interactions become stronger, which corresponds to the formation of denser coacervates. To distinguish the roles of Coulomb interactions and density, here we compare the dynamics of coacervates to those of neutral, semidilute solutions at the same density. Both systems exhibit a universal dynamical behavior in the connectivity-dominated (subdiffusion and normal diffusion) regimes, but the monomer relaxation time in coacervates is much longer and increases with increasing Bjerrum length. This is similar to the cage effect observed in glass-forming polymers, but the local dynamical slowdown is caused here by strong Coulomb attractions (ion pairing) between oppositely charged monomers. Our findings provide a microscopic framework for the quantitative understanding of coacervate dynamics and rheology.
Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1774490
Journal Information:
ACS Macro Letters, Journal Name: ACS Macro Letters Journal Issue: 9 Vol. 9; ISSN 2161-1653
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English

References (33)

Glass transition of polymer melts: test of theoretical concepts by computer simulation journal January 2003
Protein/polysaccharide complexes and coacervates in food systems journal September 2011
Development of the modern theory of polymeric complex coacervation journal January 2017
Linear viscoelasticity of complex coacervates journal January 2017
Phase separation: Bridging polymer physics and biology journal February 2019
Ultraviscosity in Entangled Polyelectrolyte Complexes and Coacervates journal May 2020
Complex Coacervate of Weakly Charged Polyelectrolytes: Diagram of States journal May 2018
Complex Coacervation in Polyelectrolytes from a Coarse-Grained Model journal August 2018
Structure of Liquid Coacervates Formed by Oppositely Charged Polyelectrolytes journal November 2018
Control of Dynamics in Polyelectrolyte Complexes by Temperature and Salt journal February 2019
Unified Entanglement Scaling for Flexible, Semiflexible, and Stiff Polymer Melts and Solutions journal February 2020
Microscopic Structure of Compacted Polyelectrolyte Complexes: Insights from Molecular Dynamics Simulations journal January 2019
Dynamics of Entangled Solutions of Associating Polymers journal February 2001
Scaling Theory of Diblock Polyampholyte Solutions journal October 2005
Electrostatic Persistence Length of Semiflexible and Flexible Polyelectrolytes journal November 2005
Regimes of Conformational Transitions of a Diblock Polyampholyte journal August 2006
Rouse Dynamics of Polyelectrolyte Solutions:  Molecular Dynamics Study journal October 2007
Linear Viscoelasticity from Molecular Dynamics Simulation of Entangled Polymers journal September 2007
Linear Viscoelasticity of Polyelectrolyte Complex Coacervates journal February 2013
Thermoreversible Gelation in Solutions of Associating Polymers. 2. Linear Dynamics journal January 1998
Protein Encapsulation via Polypeptide Complex Coacervation journal October 2014
Phosphorylation-mediated RNA/peptide complex coacervation as a model for intracellular liquid organelles journal December 2015
Molecular engineering solutions for therapeutic peptide delivery journal January 2017
Structure and rheology of polyelectrolyte complex coacervates journal January 2018
Recent progress in the science of complex coacervation journal January 2020
Equilibration of long chain polymer melts in computer simulations journal December 2003
Theory of dynamic barriers, activated hopping, and the glass transition in polymer melts journal July 2004
Dynamics of entangled linear polymer melts:  A molecular‐dynamics simulation journal April 1990
Site-specific perspective on interactions in polyelectrolyte complexes: Toward quantitative understanding journal October 2018
Dynamics of a supercooled polymer melt above the mode-coupling critical temperature: cage versus polymer-specific effects journal July 2000
Relaxation Dynamics at Different Time Scales in Electrostatic Complexes: Time-Salt Superposition journal November 2010
Beyond Oil and Water--Phase Transitions in Cells journal August 2012
Liquid phase condensation in cell physiology and disease journal September 2017

Similar Records

Polyelectrolyte Complex Coacervate Assembly with Cellulose Nanofibers
Journal Article · Mon Jul 06 20:00:00 EDT 2020 · ACS Omega · OSTI ID:1649582

The Effect of Salt on the Complex Coacervation of Vinyl Polyelectrolytes
Journal Article · Sun Jun 01 00:00:00 EDT 2014 · Polymers · OSTI ID:1394040