Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids

Motohiko Tanaka, A. Yu Grosberg, Toyoichi Tanaka

    Research output: Contribution to journalArticle

    Abstract

    The multichain effect and also the effect of added salt on randomly copolymerized charged polymers (polyampholytes) in a Langevin fluid are studied with the use of molecular dynamics simulations. The monomers of opposite signs tend to form loose complexes, which makes the Coulomb force attractive on average. With multichain polyampholytes, the typical state at high temperature is a container-bound one-phase state of separated chains with a substantial void among them. The association and dissociation processes occur repeatedly, with the former process a few times faster than the latter. A glass transition occurs when temperature is lowered. A compact and glassy globule in a segregated phase, which resembles that of a single-chain polyampholyte, is a typical state at low temperature due to the Coulomb force. The probability of losing this state is as low as Pdis∼exp(-N3/2), with N the number of monomers. The critical temperature defined by overlapping of the chains increases with molecular weight and stiffness of the chains, and is less sensitive to the number of the chains. An alternate charge sequence makes a difference only when its block size is quite small. The addition of salt suppresses the formation of a dense globule by shielding the electric field; however, this is not effective when the salt ions are not allowed to penetrate well into the globule.

    Original languageEnglish (US)
    Pages (from-to)8176-8188
    Number of pages13
    JournalJournal of Chemical Physics
    Volume110
    Issue number16
    StatePublished - Apr 22 1999

    Fingerprint

    Molecular dynamics
    Polymers
    Salts
    globules
    molecular dynamics
    salts
    Fluids
    fluids
    polymers
    Monomers
    Temperature
    monomers
    Shielding
    Containers
    Glass transition
    containers
    Molecular weight
    Electric fields
    Stiffness
    Association reactions

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics

    Cite this

    Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids. / Tanaka, Motohiko; Yu Grosberg, A.; Tanaka, Toyoichi.

    In: Journal of Chemical Physics, Vol. 110, No. 16, 22.04.1999, p. 8176-8188.

    Research output: Contribution to journalArticle

    Tanaka, Motohiko ; Yu Grosberg, A. ; Tanaka, Toyoichi. / Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids. In: Journal of Chemical Physics. 1999 ; Vol. 110, No. 16. pp. 8176-8188.
    @article{c3027950c9d14db0af0618c11a73719e,
    title = "Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids",
    abstract = "The multichain effect and also the effect of added salt on randomly copolymerized charged polymers (polyampholytes) in a Langevin fluid are studied with the use of molecular dynamics simulations. The monomers of opposite signs tend to form loose complexes, which makes the Coulomb force attractive on average. With multichain polyampholytes, the typical state at high temperature is a container-bound one-phase state of separated chains with a substantial void among them. The association and dissociation processes occur repeatedly, with the former process a few times faster than the latter. A glass transition occurs when temperature is lowered. A compact and glassy globule in a segregated phase, which resembles that of a single-chain polyampholyte, is a typical state at low temperature due to the Coulomb force. The probability of losing this state is as low as Pdis∼exp(-N3/2), with N the number of monomers. The critical temperature defined by overlapping of the chains increases with molecular weight and stiffness of the chains, and is less sensitive to the number of the chains. An alternate charge sequence makes a difference only when its block size is quite small. The addition of salt suppresses the formation of a dense globule by shielding the electric field; however, this is not effective when the salt ions are not allowed to penetrate well into the globule.",
    author = "Motohiko Tanaka and {Yu Grosberg}, A. and Toyoichi Tanaka",
    year = "1999",
    month = "4",
    day = "22",
    language = "English (US)",
    volume = "110",
    pages = "8176--8188",
    journal = "Journal of Chemical Physics",
    issn = "0021-9606",
    publisher = "American Institute of Physics Publising LLC",
    number = "16",

    }

    TY - JOUR

    T1 - Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids

    AU - Tanaka, Motohiko

    AU - Yu Grosberg, A.

    AU - Tanaka, Toyoichi

    PY - 1999/4/22

    Y1 - 1999/4/22

    N2 - The multichain effect and also the effect of added salt on randomly copolymerized charged polymers (polyampholytes) in a Langevin fluid are studied with the use of molecular dynamics simulations. The monomers of opposite signs tend to form loose complexes, which makes the Coulomb force attractive on average. With multichain polyampholytes, the typical state at high temperature is a container-bound one-phase state of separated chains with a substantial void among them. The association and dissociation processes occur repeatedly, with the former process a few times faster than the latter. A glass transition occurs when temperature is lowered. A compact and glassy globule in a segregated phase, which resembles that of a single-chain polyampholyte, is a typical state at low temperature due to the Coulomb force. The probability of losing this state is as low as Pdis∼exp(-N3/2), with N the number of monomers. The critical temperature defined by overlapping of the chains increases with molecular weight and stiffness of the chains, and is less sensitive to the number of the chains. An alternate charge sequence makes a difference only when its block size is quite small. The addition of salt suppresses the formation of a dense globule by shielding the electric field; however, this is not effective when the salt ions are not allowed to penetrate well into the globule.

    AB - The multichain effect and also the effect of added salt on randomly copolymerized charged polymers (polyampholytes) in a Langevin fluid are studied with the use of molecular dynamics simulations. The monomers of opposite signs tend to form loose complexes, which makes the Coulomb force attractive on average. With multichain polyampholytes, the typical state at high temperature is a container-bound one-phase state of separated chains with a substantial void among them. The association and dissociation processes occur repeatedly, with the former process a few times faster than the latter. A glass transition occurs when temperature is lowered. A compact and glassy globule in a segregated phase, which resembles that of a single-chain polyampholyte, is a typical state at low temperature due to the Coulomb force. The probability of losing this state is as low as Pdis∼exp(-N3/2), with N the number of monomers. The critical temperature defined by overlapping of the chains increases with molecular weight and stiffness of the chains, and is less sensitive to the number of the chains. An alternate charge sequence makes a difference only when its block size is quite small. The addition of salt suppresses the formation of a dense globule by shielding the electric field; however, this is not effective when the salt ions are not allowed to penetrate well into the globule.

    UR - http://www.scopus.com/inward/record.url?scp=0343946951&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=0343946951&partnerID=8YFLogxK

    M3 - Article

    VL - 110

    SP - 8176

    EP - 8188

    JO - Journal of Chemical Physics

    JF - Journal of Chemical Physics

    SN - 0021-9606

    IS - 16

    ER -