The morphology of poly(styrene-ran-styrene sulfonate) (P(S-SS_x)) ionomers has been investigated extensively by several research groups.[1-3]  However, only our 2001 publication has applied the method of scanning transmission electron microscopy (STEM) to probe the size, shape and spatial distribution of the ionic aggregates is these ionomers.[4]  This analytical electron microscopy method minimizes phase contrast that can obscures nano-scale features and accentuates differences in atomic number.  We recently reported quantitative agreement between results obtained by STEM and by small angle x-ray scattering (SAXS) in a Cu-neutralized poly(styrene-ran-methacrylic acid) (SMAA) ionomer.[5]  This is the first report of quantitative agreement regarding the size of spherical ionic aggregates as determined by an imaging and a scattering method.  We now apply these STEM and SAXS methods to characterize the morphologies of P(S-SS_x) random copolymers neutralized with various cations.  Combining direct imaging and X-ray scattering of sulfonated polystyrene systems will resolve uncertainties in the morphologies of these materials and serve as a guide to explain its many unique physical properties.  [1] Yarusso, D.; Cooper, S. L., Macromolecules 1983, 16, 1871.

[2]O'Connell, E.M.; Root; T.W.; Cooper, S.L., Macromolecules 1995, 11, 3995.

[3] Ding, S.Y.; Hubbard, S.R.; Hodgson, K.O; Register, R.R.; Cooper, S.L., Macromolecules, 1988, 21, 1698.

[4] Kirkmeyer, B. P.; Weiss, R. A.; Winey, K. I., Journal of Polymer Science: Part B: Polymer Physics 2001, 39, 477.

[5] Benetatos, N.M.; Winey, K.I., Macromolecules, submitted.