Predicting the Flory-Huggins χ Parameter for Polymers with Stiffness Mismatch from Molecular Dynamics Simulations
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
Author to whom correspondence should be addressed.
Academic Editor: Martin Kröger
Received: 4 May 2016 / Revised: 13 June 2016 / Accepted: 16 June 2016 / Published: 22 June 2016
The Flory–Huggins χ
parameter describes the excess free energy of mixing and governs phase behavior for polymer blends and block copolymers. For chemically-distinct nonpolar polymers, the value of χ
is dominated by the mismatch in cohesive energy densities of the monomers. For blends of chemically-similar polymers, the entropic portion of χ
, arising from non-ideal local packing, becomes more significant. Using polymer field theory, Fredrickson et al. predicted that a difference in backbone stiffness can result in a positive χ
for chains consisting of chemically-identical monomers. To quantitatively investigate this phenomenon, we perform molecular dynamic (MD) simulations for bead-spring chains, which differ only in stiffness. From the simulations, we apply a novel thermodynamic integration to extract χ
as low as
per monomer for blends with stiffness mismatch. To compare with experiments, we introduce a standardized effective monomer to map real polymers onto our bead-spring chains. The predicted χ
agrees well with experimental values for a wide variety of pairs of chemically-similar polymers.
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MDPI and ACS Style
Kozuch, D.J.; Zhang, W.; Milner, S.T. Predicting the Flory-Huggins χ Parameter for Polymers with Stiffness Mismatch from Molecular Dynamics Simulations. Polymers 2016, 8, 241.
Kozuch DJ, Zhang W, Milner ST. Predicting the Flory-Huggins χ Parameter for Polymers with Stiffness Mismatch from Molecular Dynamics Simulations. Polymers. 2016; 8(6):241.
Kozuch, Daniel J.; Zhang, Wenlin; Milner, Scott T. 2016. "Predicting the Flory-Huggins χ Parameter for Polymers with Stiffness Mismatch from Molecular Dynamics Simulations." Polymers 8, no. 6: 241.
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