N2D ~ 164

1
Reconciling STEM SAXS for Ionomer
MorphologiesKaren I. Winey, University of
Pennsylvania, DMR- 0549116
SAXSYarusso-CooperFitting ParametersR1 0.5
nm RCA 0.75 nmVp 5 nm3
First quantitative reconciliation of size (R1)
and number density (1/Vp) of ionic aggregate in
an ionomer, namely Cu-neutralized
poly(styrene-ran-methacrylic acid).

• SAXS analysis includes the Yarusso-Cooper model
  (yellow) and Lorentzians for the higher angle
  peaks associated with polystyrene (blue).
• To account for overlap in the STEM images, we
  simulated the 3D real-space morphology (far left)
  using the fitting parameters for the scattering
  model and project a 2D image (left). The ratio
  of 3D objects to 2D features depends on the
  specimen thickness (t). Thus, the local specimen
  thickness, as determined by EELS during the STEM
  experiment, was used to determine the
  corresponding number of 3D objects. The number
  density density determined by SAXS and STEM are
  in agreement.

Simulations
N2D 164
t 25 nmN3D3125
Benetatos, Heiney, Winey, Macromolecules,
2006. Benetatos, Chan, Heiney, Winey, in
preparation.
2
Reconciling STEM SAXS for Ionomer
MorphologiesKaren I. Winey, University of
Pennsylvania, DMR- 0549116
Summer 2006 REU Bruce Hilman worked closely with
Prof. Winey for 12 weeks testing the rheological
and adhesive properties of polyethylene-based
ionomers. These materials are being explored for
new cryogenic applications in an emerging
collaboration with between UPenn and NASA.
With the Public Transferring the enthusiasm for
emerging science and new technologies is a
hallmark of Prof. Wineys classroom teaching and
public forums. Earlier this year Prof. Winey met
with high school teachers over lunch at the
American Physical Society Meeting. Pictured below
are pre-college students learning about materials
science.

Polymer Electron Microscopy Expertise Electron
microscopy of polymers appears to be a vanishing
expertise in industry. Prof. Winey, in
collaboration with Penns Regional Nanotechnology
Facility, is tutoring active scientists from a
variety of settings about the power of standard
electron microscopy as well as the analytical
electron microscopy methods developed within this
grant.