Proton dissociation of sulfonated polysulfones: influence of molecular structure and conformation
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The dissociation behavior of proton conducting sulfonated polysulfones has been investigated by combining electrophoretic NMR, pulsed magnetic field gradient NMR and conductivity meas- urements on monomeric and polymeric samples with concentrations of ionic groups in the range where dissociation is not complete (IEC = 4.55 – 7.04 meq g-1). In this regime, counterion con- densation is shown to critically depend on details of the molecular structure, and all atom MD simulations reveal the formation of well-defined ionic aggregates (e.g. triple ions). The corre- sponding global minima of the free energy are suggested to be the result of a delicate balance of the energetics involved in conformational changes, formation of ionic aggregates and solvation. This goes beyond Manning’s counterion condensation theory and has important implications for the development of membranes with high ionic conductivity as needed for many electrochemical applications such as fuel cells and batteries.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Publication status||Published - 2015|
Publication Date (Web): February 5, 2015