Understanding the Mechanism of Anomalous Viscosity–Molecular Weight Relationships of Diolic Perfluoropoly (Oxyethylene-ran-oxymethylene): What is Missing in the Debye–Bueche Model?

Authors

  • Yongjin Wang,

    1. Department of Chemical and Petroleum Engineering, University of Pittsburgh, 1237 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, USA
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  • Kara T. Williams,

    1. Phasex Corporation, 360 Merrimack Street, Lawrence, MA 01843, USA
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  • Lei Li

    Corresponding author
    1. Department of Chemical and Petroleum Engineering, University of Pittsburgh, 1237 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, USA
    • Department of Chemical and Petroleum Engineering, University of Pittsburgh, 1237 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, USA.
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Abstract

For decades, the viscosity (η)–molecular weight (M) relationship of linear polymer melts has been successfully described by the Debye–Bueche model when M is lower than critical molecular weight (Mc). However, recent studies on diolic perfluoropoly (oxyethylene-ran-oxymethylene) (DPFPO), a linear polymer with polar endgroups, raise uncertainty on the validity of Debye–Bueche model. Experimental results show that the Debye–Bueche model does not hold for DPFPO, which has been attributed to the fact that the strong intermolecular endgroup–endgroup coupling is not considered in original Debye–Bueche model. A modified molecular-level model, in which the endgroup–endgroup coupling is taken into consideration, is proposed to interpret the anomalous ηM relationship of DPFPO.

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