Structure and "surfactochromic" properties of conjugated polyelectrolyte (CPE): Surfactant complexes between a cationic polythiophene and SDS in water

Matti Knaapila, Rachel C. Evans, Vasil M. Garamus, László Almásy, Noémi K. Székely, Andrea Gutacker, Ullrich Scherf, Hugh D. BurrowsO

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56 Citations (Scopus)

Abstract

We report on the phase transitions, solution structure, and consequent effect on the photophysical properties of poly[3-(6-trimethylammoniumhexyl) thiophene] bromide (P3TMAHT) in aqueous sodium dodecylsulfate (SDS). Polythiophene was mixed with SDS or deuterated SDS to form P3TMAHT(SDS)x complex (x = the molar ratio of surfactant over monomer units) in D 2O and studied by small-angle neutron and X-ray scattering (SANS/SAXS) and optical spectroscopy. At room temperature, P3TMAHT forms charged aggregates with interparticle order. The addition of SDS eliminates the interparticle order and leads to rod-like (x=1/5) or sheet-like polymer-SDS aggregates (x=1/2 to 1) containing rod-like (x=1/5 to 1/2) or sheet-like (x=1/2 to 1) polymer associations. Partial precipitation occurs at the charge compensation point (x = 1). Ellipsoidal particles without interparticle order, reminiscent of SDS micelles modified by separated polymer chains, occur for x=2 to 5. Free SDS micelles dominate for x=20. Structural transitions lead to a concomitant variation in the solution color from red (P3TMAHT) to violet (x=1/5 to 1) to yellow (x > 2). The photoluminescence fingerprint changes progressively from a broad featureless band (x = 0) through the band narrowing and appearance of vibronic structure (x=1/5 to 1) to the return to a blue-shifted broad emission band (x=5). The polymer stiffness reaches a maximum for x=1, which leads to minimization of the Stokes shift (0.08 eV). This work gives fundamental information upon how surfactant complexation can influence both the solution structure and photophysical properties of a water-soluble polythiophene.

Original languageEnglish
Pages (from-to)15634-15643
Number of pages10
JournalLangmuir
Volume26
Issue number19
DOIs
Publication statusPublished - Oct 5 2010

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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    Knaapila, M., Evans, R. C., Garamus, V. M., Almásy, L., Székely, N. K., Gutacker, A., Scherf, U., & BurrowsO, H. D. (2010). Structure and "surfactochromic" properties of conjugated polyelectrolyte (CPE): Surfactant complexes between a cationic polythiophene and SDS in water. Langmuir, 26(19), 15634-15643. https://doi.org/10.101/la102591b