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Frank S. Bates - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Conformational Asymmetry on Polymer−Polymer Interactions: An Entropic or Enthalpic Effect?
    Macromolecules, 2002
    Co-Authors: Kristoffer Almdal, Marc A. Hillmyer, Frank S. Bates
    Abstract:

    The order-to-disorder transition (ODT) of 21 compositionally symmetric diblock coPolymers consisting of various combinations of poly(ethylene) (PE), poly(ethyl ethylene) (PEE), poly(ethylene−propylene) (PEP), poly(ethylene oxide) (PEO), and poly(dimethylsiloxane) (PDMS) was used as a measure of the strength of the interaction between the Polymers. Conformational asymmetry makes a contribution to Polymer−Polymer Thermodynamics that is not explainable within existing simple theories. For a series of PDMS−hydrocarbon diblock coPolymers the observed phase behavior can be rationalized through a self-consistent set of solubility parameters. However, this model as well as other models breaks down when the phase behavior of a series of PEO−hydrocarbon block coPolymers is included. We suggest that conformational asymmetry leads to an enthalpic contribution to the Flory−Huggins parameter χ through an effective coordination number which is maximized when both of the blocks have large conformational symmetry paramete...

  • Conformational asymmetry and Polymer-Polymer Thermodynamics
    Macromolecules, 1994
    Co-Authors: Frank S. Bates, Glenn H. Fredrickson
    Abstract:

    The origins of conformational asymmetry effects in Polymer-Polymer Thermodynamics are briefly reviewed and a new expression is provided for quantitative assessment of these effects in linear homoPolymer mixtures. Differences in conformational (R g ) and volume-filing (V) characteristics can lead to a nonlocal excess entropy of mixing that is readily parametrized in terms of e= (β A /β B ) 2 , where β 2 = R g 2 /V

  • Composition dependence of the interaction parameter in isotopic Polymer blends
    Macromolecules, 1994
    Co-Authors: J. D. Londono, A. H. Narten, George D. Wignall, Kevin G. Honnell, E. T. Hsieh, T. W. Johnson, Frank S. Bates
    Abstract:

    Isotopic Polymer mixtures lack the structural asymmetries and specific interactions encountered in blends of chemically distinct species. In this respect, they form ideal model systems for exploring the limitations of the widely-used Flory-Huggins (FH) lattice model and for testing and improving new theories of Polymer Thermodynamics. The FH interaction parameter between deuterium-labeled and unlabeled segments of the same species ([sub [chi]HD]) should in principle be independent of concentration ([phi]), through previous small-angle neutron scattering (SANS) experiments have shown that it exhibits a minimum at [phi] [approximately] 0.5 for poly(vinylethylene) (PVE) and poly(ethylethylene) (PEE). The authors report new data on polyethylene (PE) as a function of molecular weight, temperature (T), and [phi], which show qualitatively similar behavior. However, measurements on [sub [chi]HD]([phi]) for polystyrene (PS) show a maximum at [phi] [approximately]0.5, in contrast to PVE, PEE, and PE. Reproducing the concentration dependence of [phi] in different model isotopic systems should serve as a sensitive test of the way in which theories of Polymer Thermodynamics can account for the details of the local packing and also the effects of noncombinatorial entropy, which appear to be the main cause of the variation of [sub [chi]HD]([phi]) for PE. These data also serve to quantifymore » the effects of isotopic substitution in SANS experiments on polyolefin blends and thus lay the ground work for definitive studies of the compatibility of branched and linear polyethylenes.« less

Glenn H. Fredrickson - One of the best experts on this subject based on the ideXlab platform.

  • Conformational asymmetry and Polymer-Polymer Thermodynamics
    Macromolecules, 1994
    Co-Authors: Frank S. Bates, Glenn H. Fredrickson
    Abstract:

    The origins of conformational asymmetry effects in Polymer-Polymer Thermodynamics are briefly reviewed and a new expression is provided for quantitative assessment of these effects in linear homoPolymer mixtures. Differences in conformational (R g ) and volume-filing (V) characteristics can lead to a nonlocal excess entropy of mixing that is readily parametrized in terms of e= (β A /β B ) 2 , where β 2 = R g 2 /V

Herbert Baur - One of the best experts on this subject based on the ideXlab platform.

S H Anastasiadis - One of the best experts on this subject based on the ideXlab platform.

  • Polymer Thermodynamics liquid Polymer containing mixtures
    2011
    Co-Authors: Sabine Enders, B A Wolf, S H Anastasiadis
    Abstract:

    Making Flory-Huggins Practical: Thermodynamics of Polymer-Containing Mixtures, by B. A. Wolf * Aqueous Solutions of Polyelectrolytes: Vapor-Liquid Equilibrium and Some Related Properties, by G. Maurer, S. Lammertz, and L. Ninni Schafer * Gas-Polymer Interactions: Key Thermodynamic Data and Thermophysical Properties, by J.-P. E. Grolier, and S. A.E. Boyer * Interfacial Tension in Binary Polymer Blends and the Effects of CoPolymers as Emulsifying Agents, by S. H. Anastasiadis * Theory of Random CoPolymer Fractionation in Columns, by Sabine Enders * Computer Simulations and Coarse-Grained Molecular Models Predicting the Equation of State of Polymer Solutions, by K. Binder, B. Mognetti, W. Paul, P. Virnau, and L. Yelash * Modeling of Polymer Phase Equilibria Using Equations of State, by G. Sadowski

E. O. Smirnov - One of the best experts on this subject based on the ideXlab platform.

  • Theory of nematic ordering in supramolecular systems: Self-assembly of mesogenic groups and self-organization of the system
    Polymer Science Series A, 2016
    Co-Authors: T. M. Birshtein, V. M. Amoskov, E. O. Smirnov
    Abstract:

    The behaviors of two systems are considered: a low-molecular system (a binary mixture of low-molecular components) and a Polymer system (mixture of a macromolecules and a low-molecular dopant) whose components reversibly bind to form dimers capable of liquid-crystal ordering. The general theory of binary-mixture structuring, where two processes occur—self-assembly of mesogenic dimers of the mixture components and their self-organization—is presented. The theory demonstrates general laws of the behavior of low-molecular and Polymer systems as well as differences related to the features of Polymer Thermodynamics.