Ordering dynamics of compositionally asymmetric styrene-isoprene block copolymers

J. La Monte Adams, Daniel J. Quiram, William W. Graessley, Richard Alan Register, Gary R. Marchand

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94 Scopus citations

Abstract

We investigate the development of mesophase order in compositionally asymmetric (13 wt % styrene) polystyrene-polyisoprene (SI) diblock and SIS triblock copolymers. The equilibrium ordered morphology of these polymers is a body-centered-cubic (bcc) lattice of spherical S microdomains. The ordering kinetics are measured by quenching the material from above the order-disorder transition temperature (TODT) to a temperature when the ordered phase is stable and following the structure development by time-resolved small-angle X-ray scattering and dynamic oscillatory rheological measurements. The kinetics are significantly slower than those observed for nearly symmetric polymers of similar TODT, resulting in a wider range of experimentally accessible quench depths. The temporal evolution of the storage modulus G′ measured at constant frequency displays a two-step increase after a quench from above the ODT, for sufficiently low temperatures and/or high molecular weights. The long-time step corresponds to the development of a bcc lattice of spherical microdomains. while the first step results from the finite time required for large amplitude composition fluctuations to develop fully.

Original languageEnglish (US)
Pages (from-to)2929-2938
Number of pages10
JournalMacromolecules
Volume29
Issue number8
DOIs
StatePublished - Apr 8 1996

All Science Journal Classification (ASJC) codes

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

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