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
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Academic Editor: Martin Kröger
Polymers 2016, 8(6), 241; https://doi.org/10.3390/polym8060241
Received: 4 May 2016
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Revised: 13 June 2016
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Accepted: 16 June 2016
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Published: 22 June 2016
(This article belongs to the Special Issue Semiflexible Polymers)
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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Keywords:
polymers; Flory–Huggins theory; bead-spring chain; molecular dynamics; coarse grain; chain stiffness
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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. https://doi.org/10.3390/polym8060241
AMA Style
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. https://doi.org/10.3390/polym8060241
Chicago/Turabian StyleKozuch, Daniel J., Wenlin Zhang, and Scott T. Milner. 2016. "Predicting the Flory-Huggins χ Parameter for Polymers with Stiffness Mismatch from Molecular Dynamics Simulations" Polymers 8, no. 6: 241. https://doi.org/10.3390/polym8060241
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