Environmentally responsive micelles from polystyrene-poly[bis(potassium carboxylatophenoxy)phosphazene] block copolymers

Youngkyu Chang, Eric S. Powell, Harry R. Allcock

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Amphiphilic diblock copolymers that contained hydrophilic poly[bis(potassium carboxylatophenoxy)phosphazene] segments and hydrophobic polystyrene sections were synthesized via the controlled cationic polymerization of Cl 3P=NSiMe 3 with a polystyrenyl-phosphoranimine as a macromolecular terminator. These block copolymers self-associated in aqueous media to form micellar structures which were investigated by fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The size and shape of the micelles were not affected by the introduction of different monovalent cations (Li +, K +, Na +, and Cs +) into the stable micellar solutions. However, exposure to divalent cations induced intermicellar crosslinking through carboxylate groups, which caused precipitation of the ionically crosslinked aggregates from solution. This micelle-coupling behavior was reversible: the subsequent addition of monovalent cations caused the redispersion of the polystyrene-block- poly[bis(potassium carboxylatophenoxy)phosphazene] (PS-KPCPP) block copolymers into a stable micellar solution. Aqueous micellar solutions of PS-KPCPP copolymers also showed pH-dependent behavior. These attributes make PS-KPCPP block copolymers suitable for studies of guest retention and release in response to ion charge and pH.

Original languageEnglish (US)
Pages (from-to)2912-2920
Number of pages9
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume43
Issue number13
DOIs
StatePublished - Jul 1 2005

All Science Journal Classification (ASJC) codes

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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