Phase behavior of polystyrene-b-poly(methyl methacrylate) diblock copolymer

Hyungju Ahn, Du Yeol Ryu, Youngmin Kim, Kyung Wook Kwon, Jumi Lee, Junhan Cho

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


The phase behavior of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) copolymers of various molecular weights has been studied by using small-angle X-ray scattering (SAXS) and depolarized light scattering (DLS). The empirical Flory χ, determined from scattering intensity profiles for a fully disordered PS-b-PMMA copolymer, was shown to behave differently depending on temperature range. χ was described mostly by enthalpic contribution at higher temperatures, but a dominant entropie contribution appeared in χ at lower temperatures. The order-disorder transition (ODT) temperatures for the series of copolymers with the controlled molecular weights were directly measured through SAXS and DLS. The resultant ODTs were then compared with a compressible random-phase approximation theory to determine cross interactions between block components. It was found that effective χ from theory is also mostly described by enthalpic contribution, which yields a moderate change in ODT upon the increase of copolymer molecular weight. In addition, we discussed the pressure response of the copolymer using χ from theory.

Original languageEnglish
Pages (from-to)7897-7902
Number of pages6
Issue number20
Publication statusPublished - 2009 Oct 27

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry


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