Anion metathesis enabled a systematic study focused on the thermal, viscoelastic, and conductivity properties of a 4P,12 phosphonium ionenes with various counterions. Aqueous size exclusion chromatography confirmed the well-defined synthesis of 4P,12-Br from the step-growth polymerization of 1,4-bis(diphenylphosphino) butane and 1,12-dibromododecane at a 1:1 stoichiometric ratio. Subsequent anion-exchange employing a dialysis method exchanged the Br- counterion to trifluoromethanesulfonate (TfO-), bis(trifluoromethane) sulfonimide (Tf2N-), and tetrafluoroborate (BF4-) counterion. Chemical and thermal characterization revealed that anion-metathesis to more bulky and delocalized anions had resulted in profound differences in fundamental polymer properties including the glass transition temperature and thermal stability. Melt rheology was employed for time-temperature superposition analysis and suggested that larger counterions have a plasticizing effect on the viscoelasticity of the 4P,12 ionene. Additionally, ionic conductivity increased with increasing size of the counterion (Br- < BF4- < TfO- < Tf2N-) and demonstrated the viability of these novel materials as potential anion-exchange ionomeric membranes.

Influence of counterion on thermal, viscoelastic, and ion conductive properties of phosphonium ionenes

248th National Meeting (2014)

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