Effects of Counter Anion Type on Melt Rheological Properties of Hyperbranched Polyethylene Ionomers Containing Covalently Bound Quaternary Ammonium Cations.

The paper investigates the effects of counter anions of varying sizes including BF4–, PF6–, SbF6–, and Tf2N– on the rheological properties of a range of hyperbranched polyethylene ionomers containing covalently bound quaternary ammonium cations. While the choice of counter anions has no significant effect on thermal properties, distinct effects on rheological properties have been demonstrated. With the increase of counter anion size in the order from BF4– to PF6–, SbF6–, and Tf2N–, the ionic interactions of the counter anion with the quaternary ammonium ion weaken, leading to reduced terminal relaxation time, zero‐shear viscosity, and flow activation energy. The differences in these properties are most pronounced with the ionomer having Tf2N– counter anion since it is significantly larger than the others. [ABSTRACT FROM AUTHOR]