Temperature-dependent micellar structures in poly(styrene-b-isoprene) diblock copolymer solutions near the critical micelle temperature

Joona Bang, Karthik Viswanathan, Timothy P. Lodge, Moon Jeong Park, Kookheon Char

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

The temperature dependence of the micelle structures formed by poly(styrene-Wsoprene) (SI) diblock copolymers in the selective solvents diethyl phthalate (DEP) and tetradecane (C14), which are selective for the PS and PI blocks, respectively, have been investigated by small angle neutron scattering (SANS). Two nearly symmetric SI diblock copolymers, one with a perdeuterated PS block and the other with a perdeuterated PI block, were examined in both DEP and C14. The SANS scattering length density of the solvent was matched closely to either the core or the corona block. The resulting core and corona contrast data were fitted with a detailed model developed by Pedersen and co-workers. The fits provide quantitative information on micellar characteristics such as aggregation number, core size, overall size, solvent fraction in the core, and corona thickness. As temperature increases, the solvent selectivity decreases, leading to substantial solvent swelling of the core and a decrease in the aggregation number and core size. Both core and corona chains are able to relax their conformations near the critical micelle temperature due to a decrease in the interfacial tension, even though the corona chains are always under good solvent conditions.

Original languageEnglish
Article number12
Pages (from-to)11489-11500
Number of pages12
JournalJournal of Chemical Physics
Volume121
Issue number22
DOIs
Publication statusPublished - 2004 Dec 8

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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