Predicting the Flory-Huggins χ parameter for polymers with stiffness mismatch from molecular dynamics simulations

Daniel J. Kozuch, Wenlin Zhang, Scott T. Milner

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

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 c, 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 10-4 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.

Original languageEnglish (US)
Article number241
JournalPolymers
Volume8
Issue number6
DOIs
StatePublished - Jun 22 2016

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Polymers and Plastics

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