The role of polydispersity in the lamellar mesophase of model diblock copolymers

Nathaniel A. Lynd, Benjamin D. Hamilton, Marc A. Hillmyer

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42 Scopus citations


High-resolution small angle X-ray scattering (SAXS) measurements were performed on two series of poly(ethylene-alt-propylene)-b-poly(D,L-lactide) (PEP-PLA) diblock copolymer materials exhibiting differences in the widths of the poly(D,L-lactide) block molecular mass distributions as measured by their polydispersity indices (PDI PLA), At symmetric compositions of PEP-PLA (f PLA ≈ 0.5), all SAXS data were successfully fit to an established model describing the small angle scattering from lamellar mesostructures. According to this model, the increase in the PDI PLA negligibly affected the amount of lattice disorder. The apparent asymmetry of the poly(ethylene-alt-propylene)-block lamellae (φ), also determined by the fitting procedure, were more substantially affected; increasing the PDI PLA resulted in a decrease in φ. At asymmetric compositions of PEP-PLA (f PLA ≈; 0.67), only the data at the highest values of the PDI PLA could be reasonably fit to this model.

Original languageEnglish (US)
Pages (from-to)3386-3393
Number of pages8
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number24
StatePublished - Dec 15 2007


  • Block copolymers
  • Phase behavior
  • SAXS


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