Fluctuations, Order, and Disorder in Short Diblock Copolymers

Sangwoo Lee, Timothy M. Gillard, Frank S. Bates

Research output: Contribution to journalArticle

65 Scopus citations

Abstract

The phase behavior for a series of poly(1,4-isoprene-b-DL-lactide) diblock copolymers characterized by a relatively large Flory-Huggins segment-segment interaction parameter (χ) and low degrees of polymerization (N) over a range of compositions was reported. Ordered-state morphologies were deduced from small-angle x-ray scattering (SAXS) measurements, and χ(T) was determined from order-disorder transition temperatures (TODT's) associated with the compositionally symmetric specimens and assuming the mean-field theory, that is, (χN)ODT=10.5. The ODT was determined by differential scanning calorimetry, SAXS, and dynamic mechanical spectroscopy, and shown to be weakly first-order, with latent heats of transition that vary strongly with composition. We interpret this behavior in terms of the mean and Gauss interfacial curvature of the ordered-state morphologies and with respect to composition fluctuations in the disordered state. These results offer a fresh strategy for investigating weakly first-order phase transitions within the Brazovskii universality class.

Original languageEnglish (US)
Pages (from-to)3502-3513
Number of pages12
JournalAIChE Journal
Volume59
Issue number9
DOIs
StatePublished - Sep 1 2013

Keywords

  • Block copolymers
  • Fluctuations
  • Phase behavior

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