Investigations on the chain conformation of weakly charged polyelectrolyte in solvents by using efficient hybrid molecular simulations

Macromolecular Research (Impact Factor: 1.64). 12/2002; 10(6):297-303. DOI: 10.1007/BF03218322

ABSTRACT We have investigated the microstructural properties of a weakly charged polyelectrolyte modeled with both Hookean spring and
Debye-Hückel potential, by employing a novel hybrid scheme of molecular dynamics (MD) and Monte Carlo (MC) simulations. Although
the off-lattice pivot step facilitates the earlier computations stage, it gives rise to oscillations and hinders the stable
equilibrium state. In order to overcome this problem, we adopt the MC off-lattice pivot step in early stage only, and then
switch the computation to a pure MD step. The result shows that the computational speed-up compared to the previous method
is entirely above 10 to 50, without loss of the accuracy. We examined the conformations of polyelectrolyte in solvents in
terms of the end-to-end distance, radius of gyration, and structure factor with variations of the screening effects of solvent
and the monomer charges. The emphasis can favorably be given on the elongation behavior of a polyelectrolyte chain, with observing
the simultaneous snapshots.

Keywordspolyelectrolyte–molecular dynamics–Monte Carlo simulation–chain conformation–structure factor

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    ABSTRACT: We study the behavior of a uniformly charged polyelectrolyte confined in a circular cylindrical pore with constant surface potentials. From Green's function theory with an effective step-length renormalized by monomer-monomer interactions, the partition coefficient and associated chain conforma-tions are predicted in a variety of situations. Depending upon the ionic strength of surrounding fluids, the polyelectrolyte conformation may be stretched and follow a self-avoiding walk, yielding a significant reduction in the partition coefficient compared to the ideal chain result. The monomer-monomer interaction is found to be as important as the polymer-pore interaction in determining the partitioning behavior, especially in the long-chain regime, due to the characteristics of confined spaces.
    Macromolecules. 01/2000; 33(23).

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