Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations.

Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Research Abstract Details 

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Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Abstract Text:

Zhaoyang Ou,M Muthukumar,

We report a systematic study by Langevin dynamics simulation on the energetics of complexation between two oppositely charged polyelectrolytes of same charge density in dilute solutions of a good solvent with counterions and salt ions explicitly included. The enthalpy of polyelectrolyte complexation is quantified by comparisons of the Coulomb energy before and after complexation. The entropy of polyelectrolyte complexation is determined directly from simulations and compared with that from a mean-field lattice model explicitly accounting for counterion adsorption. At weak Coulomb interaction strengths, e.g., in solvents of high dielectric constant or with weakly charged polyelectrolytes, complexation is driven by a negative enthalpy due to electrostatic attraction between two oppositely charged chains, with counterion release entropy playing only a subsidiary role. In the strong interaction regime, complexation is driven by a large counterion release entropy and opposed by a positive enthalpy change. The addition of salt reduces the enthalpy of polyelectrolyte complexation by screening electrostatic interaction at all Coulomb interaction strengths. The counterion release entropy also decreases in the presence of salt, but the reduction only becomes significant at higher Coulomb interaction strengths. More significantly, in the range of Coulomb interaction strengths appropriate for highly charged polymers in aqueous solutions, complexation enthalpy depends weakly on salt concentration and counterion release entropy exhibits a large variation as a function of salt concentration. Our study quantitatively establishes that polyelectrolyte complexation in highly charged Coulomb systems is of entropic origin.

Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Publishing Authors By Initials

Z Ou,M Muthukumar,

For similar inorganic chemicals: salts research abstracts see: inorganic chemicals: salts research

PUBMED ID PMID:

MEDLINE DATE:

Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: The Journal of chemical physics

VOLUME: 124

Page Numbers: 154902

Journal Abbreviation:

ISSN: 0021-9606

DAY: 21

MONTH: Apr

YEAR: 2006

Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Information

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LANGUAGE: eng

NlmUniqueID: 375360

Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Keywords Mesh Terms:

KEYWORDS: Salts

MESH TERMS: chemistry

Chemical & Substance for Abstract: Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations. Information

Substance Name: Salts

Registry Number: 0

Grant and Affiliation Information for Entropy and enthalpy of polyelectrolyte complexation: Langevin dynamics simulations.

AFFILIATION: Department of Polymer Science and Engineering, Materials Research Science and Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003, USA.

Country: United States

AGENCY: United States NHGRI

GRANT: 1R01HG002776-01

ACRONYM: HG

MEDLINETA: J Chem Phys

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