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Scattering Neutrons along the Polyelectrolyte Complex/Coacervate Continuum
journal contribution
posted on 2018-06-18, 19:33 authored by Hadi M. Fares, Yara E. Ghoussoub, Jose D. Delgado, Jingcheng Fu, Volker S. Urban, Joseph B. SchlenoffThe 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 complexa 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.