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Author(s):
M. Tanaka, A. Yu Grosberg and T. Tanaka
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Title:
Molecular Dynamics of Structure Organization of Polyampholytes
Date of publication:
Sep. 1998
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Key words:
Strongly-coupled Coulomb system, electrically charged polymers, multichain, polyelectrolyte, polyampholyte, hysteresis, folding process, salt electrolyte solution.
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Abstract:
The dynamics and equilibrium of charged polymers of random co-polymerization (polyampholytes) are studied for both the single-chain and multichain cases with the use of molecular dynamics simulations. Nearly neutral single-chain polyampholyte has three temperature regimes, which are characterized by an elongated Gaussian coil, a transition between the coil and globular states, and a very dense globule for high, medium and low temperatures, respectively. The gyration radius of polyampholytes shows a hysteresis against slow cyclic temperature changes under the Coulomb and attractive short-range forces. The multichain polyampholyte forms a globule at low temperature and is composed of wall-bound separated chains at high temperature. The polyampholyte chains are overlapped above certain concentration or below a critical temperature due to the Coulomb force. Added salt ions screen the electric field between the monomers and make the polyampholyte soluble when density of the salt is comparable to that of the polyampholyte.
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