Reconciling STEM and SAXS for Ionomer Morphologies

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Isonomers are random copolymers with a majority of non=polar monomeric units and a minority (~5-10 mol%) of polar monomeric units, typically acids. The acid groups can be partially or fully neutralized with cations to create ionic species that self assemble to form ionic nanoaggregates. In addition to their current industrial interest as chemically resistant thermoplastics, tough coatings, permselective membranes for fuel cells, and food packaging materials, a variety of new technologies are envisioned. Wineys work with these materials focused on directly imaging the ionic aggregates using advanced electron microscopy methods, so as to provide vital insight to the interrelationships between synthesis, processing, morphology and numerous physical properties. The focus of the proposed research is to seek reconciliation between real space images collected by scanning transmission electron microscopy (STEM) and reciprocal space patterns collected by small angle x-ray scattering (SAXS). Model materials will be employed. The proposed research is divided into three segments: further STEM and SAXS technique refinements. Poly(styrene-ran-methacrylic acid) copolymers neutralized with transition metals, and poly(ethylene-ran-methacrylic acid) copolymers neutralized with transition metals. %%% Ionomers are a class of plastics that are currently used as chemically resistant plastics, tough coatings (golf balls) permselective membranes for fuel cells, and food packaging materials, and a variety of new technologies are envisioned, e.g., protection against chemical warfare. Designing better ionomers for these applications requires understanding the interdependencies of structure, processing, and properties. Winey is characterizing the nanoscale structure of ionomers using advanced election microscopy and standard x-ray scattering tools. Industrial , academic and military scientists have a particular interest in Wineys efforts to reconcile microscopy and scattering data from ionomers, because in instances of successful reconciliation the wider community can subsequently rely on the faster scattering method with confidence. Providing this information will enable scientists and engineers to better establish the interdependencies and design improved materials. Winey will continue to accept speaking engagements that encourage the participation of women in science and engineering.