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Aggregation of Ion Pairs in Sodium Poly(styrenesulfonate) Ionomers: Theory and Experiment
Macromolecules (1984)
  • William MacKnight, University of Massachusetts Amherst
  • W. C. Forsman
  • J. S. Higgins
Abstract
Theory of the effect of ion-pair clustering on chain dimensions was compared with mean-square radii of gyration determined on poly(styrenesulfonic acid) ionomers by small-angle neutron scattering (SANS). Reasonable agreement between theory and experiment was obtained by setting the surface energy of cluster formation (the only arbitrary parameter) equal to 8.9 kcal/mol of ion pairs. Since theory predicted more ion pairs per cluster than could be accommodated in spherical clusters, lamellar cluster formation was assumed. Theory predicted about 15 and 12 ion pairs per cluster for polymer containing 1.9 and 8.5 mol % ionic repeat units, respectively. The data suggest, however, that the clusters themselves may aggregate to form higher order structures for ionic concentrations greater than about 5-6 mol % . The theory was also compared with results from SANS chain dimension measurements on the acid precursor of the 1.9 mol % ionomer. Predictions of chain extension due to carboxyl-carboxyl hydrogen bonding were in good agreement with the reported value for the polymer if about 50% of the carboxyl groups participate in hydrogen bonding. The reported mean-square radius of gyration was not, however, known to sufficient accuracy to offer a critical test of the theory. 
Keywords
  • Aggregation,
  • Ion Pairs,
  • Sodium Poly(styrenesulfonate),
  • Ionomers,
  • Theory,
  • Experiment
Disciplines
Publication Date
1984
Citation Information
William MacKnight, W. C. Forsman and J. S. Higgins. "Aggregation of Ion Pairs in Sodium Poly(styrenesulfonate) Ionomers: Theory and Experiment" Macromolecules Vol. 17 (1984) p. 490 - 494
Available at: http://works.bepress.com/william_macknight/108/