Solubilization of poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl} in Water by Non-Ionic Amphiphiles

Research output: Contribution to journalArticle

Abstract

In the presence of the nonionic alkyloxyethylene surfactant n-dodecylpentaoxyethylene glycol ether (C12E5), the
anionic conjugated polyelectrolyte (CPE) poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}
(PBS-PFP) dissolves in water, leading to a blue shift in fluorescence and dramatic increases in fluorescence quantum
yields above the surfactant critical micelle concentration (cmc). No significant changes were seen with a poly(ethylene
oxide) of similar size to the surfactant headgroup, confirming that specific surfactant-polyelectrolyte interactions are
important. From UV-visible and fluorescence spectroscopy, dynamic light scattering (DLS), small-angle X-ray
scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), and electrical conductivity, together with
our published NMR and small-angle neutron scattering (SANS) results, we provide a coherent model for this behavior
in terms of breakup of PBS-PFP clusters through polymer-surfactant association leading to cylindrical aggregates
containing isolated polymer chains. This is supported by molecular dynamics simulations, which indicate stable
polymer-surfactant structures and also provide indications of the tendency of C12E5 to break up polymer clusters to
form these mixed polymer-surfactant aggregates. Radial electron density profiles of the cylindrical cross section
obtained from SAXS results reveal the internal structure of such inhomogeneous species. DLS and cryo-TEM results
show that at higher surfactant concentrations the micelles start to grow, possibly partially due to formation of long,
threadlike species. Other alkyloxyethylene surfactants, together with poly(propylene glycol) and hydrophobically
modified poly(ethylene glycol), also solubilize this polymer in water, and it is suggested that this results from a balance
between electrostatic (or ion-dipole), hydrophilic, and hydrophobic interactions. There is a small, but significant,
dependence of the emission maximum on the local environment.

Details

Authors
  • Hugh D. Burrows
  • Maria J. Tapia
  • Sofia M. Fonesca
  • Swapna Pradhan
  • Ullrich Scherf
  • Cláudia L. Silva
  • Alberto A. C. C. Pais
  • Artur J. M. Valente
  • Karin Schillén
  • Viveka Alfredsson
  • Anna Carnerup
  • Matija Tomšič
  • Andrej Jamnik
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Chemistry
Original languageEnglish
Pages (from-to)5545-5556
JournalLangmuir
Volume25
Issue number10
Publication statusPublished - 2009
Publication categoryResearch
Peer-reviewedYes