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.
