Estimating the segregation strength of microphase-separated diblock copolymers from the interfacial width

Adam B. Burns, Dane Christie, William D. Mulhearn, Richard A. Register

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The ever-growing catalog of monomers being incorporated into block polymers affords exceptional control over phase behavior and nanoscale structure. The segregation strength, χN, is the fundamental link between the molecular-level detail and the thermodynamics. However, predicting phase behavior mandates at least one experimental measurement of χN for each pair of blocks. This typically requires access to the disordered state. We describe a method for estimating χN from small-angle X-ray scattering measurements of the interfacial width between lamellar microdomains, tx, in the microphase-separated melt. The segregation strength is determined by comparing tx to self-consistent field theory calculations of the intrinsic interfacial width, ti, as a function of the mean-field χN. The method is validated using a series of independent experimental measurements of tx and χN, measured via the order–disorder transition temperature, TODT. The average absolute relative difference between χN calculated from tx and the value calculated from TODT is a modest 11%. Corrections for nonplanarity of the interfaces are investigated but do not improve the agreement between the experiments and theory. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. J. Polym. Sci., Part B: Polym. Phys.

Original languageEnglish (US)
Pages (from-to)932-940
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number14
StatePublished - Jul 15 2019

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Materials Chemistry
  • Polymers and Plastics
  • Physical and Theoretical Chemistry


  • block copolymers
  • microphase separation
  • polymer interfaces
  • self-consistent field theory
  • small-angle X-ray scattering


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