Scattering Neutrons along the Polyelectrolyte Complex/Coacervate Continuum

Hadi M. Fares, Yara E. Ghoussoub, Jose D. Delgado, Jingcheng Fu, Volker S. Urban, Joseph B. Schlenoff

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58 Scopus citations

Abstract

The coil size of narrow molecular weight distribution deuterated poly(styrenesulfonate), PSS, within a polyelectrolyte complex doped with KBr was tracked across the continuum from solid to coacervate to solution using small-angle neutron scattering. While PSS alone in solution exhibited the familiar and pronounced "polyelectrolyte effect" of coil shrinkage with increasing [KBr], the radius of gyration Rg of the PSS in the complex remained surprisingly constant up to 1.4 M KBr, which is close to the transition between complex and coacervate behavior. Thereafter, Rg decreased with increasing KBr, remaining slightly larger than Rg for PSS in KBr alone. Upturns in the scattering at low angle, seen for complexes in lower [KBr], are consistent with porosity, observed macroscopically as whitening of the bulk complex - a universal property of polyelectrolyte complexes. Reasons for this porosity, imaged by scanning electron microscopy, are discussed. At high q ranges, a correlation peak between deuterated coils of PSS was observed.

Original languageEnglish
Pages (from-to)4945-4955
Number of pages11
JournalMacromolecules
Volume51
Issue number13
DOIs
StatePublished - Jul 10 2018

Funding

This work was supported by a grant from the National Science Foundation (DMR-1506824), with additional support provided by the Florida State University Office of Research. Neutron scattering research at Bio-SANS was supported by the DOE Biological and Environmental Research (BER) program using resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.

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