Title: Flexible polyelectrolyte chain in a strong electrolyte solution: Insight into equilibrium properties and force-extension behavior from mesoscale simulation

Abstract

Macromolecules with ionizable groups are ubiquitous in biological and synthetic systems. Due to the complex interaction between chain and electrostatic decorrelation lengths, both equilibrium properties and micro-mechanical response of dilute solutions of polyelectrolytes (PEs) are more complex than their neutral counterparts. In this paper, the bead-rod micromechanical description of a chain is used to perform hi-fidelity Brownian dynamics simulation of dilute PE solutions to ascertain the self-similar equilibrium behavior of PE chains with various linear charge densities, scaling of the Kuhn step length (l_E) with salt concentration c_s and the force-extension behavior of the PE chain. In accord with earlier theoretical predictions, our results indicate that for a chain with n Kuhn segments, l_E ~ c_s^-0.5 as linear charge density approaches 1/n. Moreover, the constant force ensemble simulation results accurately predict the initial non-linear force-extension region of PE chain recently measured via single chain experiments. Inspired by Cohen’s extraction of Warner’s force law from the inverse Langevin force law, a novel numerical scheme is developed to extract a new elastic force law for real chains from our discrete set of force-extension data similar to Padè expansion, which accurately depicts the initial non-linear region where the total Kuhn length is lessmore » than the thermal screening length.« less

Authors:

Malekzadeh Moghani, Mahdy ^[1]; Khomami, Bamin  ^[1]

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+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States). Materials Research and Innovation Lab. Dept. of Chemical and Biomolecular Engineering

Publication Date:

2016-01-12

Research Org.:

Univ. of Tennessee, Knoxville, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1469168

Alternate Identifier(s):

OSTI ID: 1234561

Grant/Contract Number:  

FG02-08ER46528

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Chemical Physics

Additional Journal Information:

Journal Volume: 144; Journal Issue: 2; Journal ID: ISSN 0021-9606

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; macromolecules; electrolytes; computer simulation; Debye length; computational models; polymer chemistry; general topology; polyelectrolytes; phase transitions; electrostatics