Phase behavior and viscoelastic properties of entangled block copolymer gels

Daniel A. Vega, John M. Sebastian, Yueh Lin Loo, Richard Alan Register

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Triblock copolymers in midblock-selective solvents can form physical gels. However, at low triblock contents (near the percolation threshold), the bridging of chains between micelles can lead to macrophase separation. Adding a styrene-isoprene diblock to a styrene-isoprene-styrene triblock copolymer in squalene can eliminate macrophase separation, yielding a wide range of stable, single-phase gels with a disordered arrangement of micelles. The plateau modulus of these triblock gels scales with the 2.2 power of polymer content, indicating the importance of entanglements in dictating the modulus. Comparing gels made from the midblock-saturated derivative of the same polymer [styrene-(ethylene-alt-propylene)-styrene] in squalene reveals that the modulus differences in the gels are a direct consequence of the difference in the entanglement molecular weight of the midblock homopolymer in bulk. Finally, the broad relaxation spectrum of these triblocks is well-described by a recent theory for the dynamics of entangled star polymers, with the breadth of the relaxation spectrum dictated by the number of entanglements per midblock in the gel.

Original languageEnglish (US)
Pages (from-to)2183-2197
Number of pages15
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume39
Issue number18
DOIs
StatePublished - Sep 18 2001

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

Keywords

  • Block copolymers
  • Entanglements
  • Gels
  • Micelles
  • Phase diagrams
  • Star polymers

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