Multinuclear NMR of Ionomers and Polymer Blends
Abstract
Many factors are known to affect the morphology and properties of ionomers, and the role that the cation local environment plays is not well understood. To better understand ionomer morphology, the cation environment in sulfonated and carboxylated ionomers was investigated using 23Na NMR. As many as three environments were seen in polydisperse sulfonated polystyrene (NaSPS): isolated sodium ions at 7 ppm, hydrated ions at 0 ppm, and aggregated ions at -12 to -23 ppm. In monodisperse NaSPS, a fourth peak at -2.7 ppm appeared at ionization levels above 1.2% and molecular weights of at least 35,000. The fraction of sodium ions held in isolated ion pairs decreased to zero while the fraction of ionic species in aggregates increased with increasing sulfonation. As the neutralization level increased, the aggregate peak shifted to higher frequency with incorporation of neutralizing NaOH. These peak positions and trends are explainable in terms of the magnetic and electric field properties of each Na+ environment.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1995
- Accession Number
- ADA334933
Entities
People
- Ellen M. O'connell
Organizations
- Air Force Research Laboratory