APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session L14: Invited Session: Understanding Ion Containing Polymer Systems using Computer Simulations
8:00 AM–11:00 AM,
Wednesday, March 5, 2014
Room: 301-303
Sponsoring
Units:
DPOLY DCOMP
Chair: Gary Grest, Sandia National Laboratories
Abstract ID: BAPS.2014.MAR.L14.4
Abstract: L14.00004 : Molecular Dynamics Simulations of Polyelectrolyte Solutions*
9:48 AM–10:24 AM
Preview Abstract
Abstract
Author:
Andrey Dobrynin
(University of Connecticut)
Polyelectrolytes are polymers with ionizable groups. In polar solvents,
these groups dissociate releasing counterions into solution and leaving
uncompensated charges on the polymer backbone. Examples of polyelectrolytes
include biopolymers such as DNA and RNA, and synthetic polymers such as
poly(styrene sulfonate) and poly(acrylic acids). In this talk I will discuss
recent molecular dynamics simulations of static and dynamic properties of
polyelectrolyte solutions. These simulations show that in dilute and
semidilute polyelectrolyte solutions the electrostatic induced chain
persistence length scales with the solution ionic strength as
$I^{\mathrm{-1/2}}$. This dependence of the chain persistence length is due
to counterion condensation on the polymer backbone. In dilute
polyelectrolyte solutions the chain size decreases with increasing the salt
concentration as \textit{R $\sim$ I}$^{-1/5}$. This is in agreement with the scaling of the
chain persistence length on the solution ionic strength, $l_{p}$\textit{ $\sim$ I}$^{-1/2}$. In semidilute solution regime at low salt concentrations the
chain size decreases with increasing polymer concentration, \textit{R $\sim$ c}$_{p}^{-1/4}$.
While at high salt concentrations one observes a weaker dependence of the
chain size on the solution ionic strength, \textit{R $\sim$ I}$^{-1/8}$. Analysis of the
simulation data throughout the studied salt and polymer concentration ranges
shows that there exist general scaling relations between multiple quantities
$X(I)$ in salt solutions and corresponding quantities $X(I_{0})$ in salt-free
solutions, $X(I)=X(I_{0})(I/I_{0})^{\beta }$. The exponent $\beta =$ -1/2 for
chain persistence length $l_{p}, \beta =$ 1/4 for solution correlation
length, $\beta =$ -1/5 and $\beta =$ -1/8 for chain size $R$ in dilute and
semidilute solution regimes respectively. Furthermore, the analysis of the
spectrum and of the relaxation times of Rouse modes confirms existence of
the single length scale (correlation length) that controls both static and
dynamic properties of semidilute polyelectrolyte solutions. These findings
confirm predictions of the scaling model of polyelectrolyte solutions.
*NSF DMR-1004576
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.L14.4