The Structure and Dynamics of Flexible Polyelectrolyte Combs

TL;DR

This study investigates the structure and dynamics of polystyrene sulphonate comb polyelectrolytes using various scattering and microrheology techniques, revealing universal behaviors and architecture-dependent properties in dilute and semi-dilute solutions.

Contribution

It provides new insights into the conformations and dynamic behaviors of comb polyelectrolytes, including a universal correlation length scaling and the impact of architecture on low-frequency viscosity.

Findings

Correlation length scales as c^-0.47, independent of architecture

High-frequency viscoelasticity matches Rouse model predictions

Architecture influences low-frequency viscosity and unentangled dynamics

Abstract

The structure and dynamics of a range of polystyrene sulphonate comb polyelectrolytes with well defined chain architectures were examined with static light scattering, dynamic light scattering, small angle neutron/X-ray scattering, particle tracking microrheology and diffusing wave spectroscopy. The chains adopted extended cylindrical conformations in dilute solutions. In semi-dilute solutions a universal behaviour was found for the correlation length (X) on the monomer concentration (c), X=(3.0/b)c^-0.47, independent of the comb architecture (b is the monomer size). The high frequency viscoelasticity (104-106Hz) is found to be in agreement with a model for the Rouse dynamics of the chains and is again independent of the architecture of the combs. However the architecture had a significant impact on the low frequency viscosity of the solutions and the particle tracking data was in good agreement with a dynamic scaling theory for the unentangled dynamics of the combs. Analogous results are found with the biological comb polyelectrolyte aggrecan.