Junction point fluctuations in microphase separated polystyrene-polyisoprene-polystyrene triblock copolymer melts. A dielectric and rheological investigation

I. Alig, G. Floudas*, A. Avgeropoulos, Nikolaos Hadjichristidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Dielectric spectroscopy is employed in two polystyrene-polyisoprene-polystyrene (SIS) triblock copolymers well below the order-to-disorder transition temperature and in the frequency range from 10-2 to 106 Hz. Small angle X-ray scattering has shown the formation of lamellar structures with a long period of about 25 nm. Besides the polyisoprene and polystyrene segmental relaxations and a slower process associated with the reorientation of the interface, we provide evidence for a new type of chain dynamics associated with the mobility of the junction points at the interface. From the relaxation strength of this process - which is very much reduced as compared to the chain relaxation in bulk polyisoprene - we extract a characteristic length of the end-to-end vector fluctuations in the interface in the range 4-6 nm. This value compares well with an independent estimate of the interfacial thickness based on thermodynamics. Dielectric spectroscopy can therefore be used as a dynamic probe of the interface in ordered triblock copolymers. Over the same temperature range rheology is influenced by a broad spectrum of modes related to the dynamics of tethered polyisoprene chains.

Original languageEnglish (US)
Pages (from-to)5004-5011
Number of pages8
JournalMacromolecules
Volume30
Issue number17
DOIs
StatePublished - Aug 25 1997

ASJC Scopus subject areas

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

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