(376ap) Enhancing Ionic Conductivity of Anion Exchange Membrane Via Incorporating Tetra-Quaternized Calix[4]Arene

Anion exchange membranes (AEMs) have been widely applied in flow redox
battery, fuel cells and electrodialysis. However, low
ionic conductivity is difficult to satisfy the requirement of such
electrochemical systems. To address this issue, trimethylamine tetra-quaternized calix[4]arene (TQCA)
was successfully synthesized and incorporated into imidazolium-functionalized
polysulfone AEMs (PSF-ImOH/TQCA).
The unique conical architecture of TQCA, i.e. cationic groups at the upper rim
and alkyl chains at the lower, makes it easy
to aggregate into a globular micelle.
The cationic groups at the outer edge of the globular micelle could involve
imidazolium groups to form big ionic clusters, which are confirmed by TEM
images and SAXS. The cavity of calix[4]arene functions as a reservoir for
water storage due to the high free volume, increasing water uptake for
effective OH^- transport and controlling
dimensional change at the same time. Consequently, the
PSF-ImOH/TQCA shows
a remarkable 1.7-fold enhancement of ionic conductivity at 25 ^oC over that of the membrane without TQCA. Additionally,
the upper or lower rims of calixarenes can be
readily functionalized, which provides more possibilities for preparation of
high-performance AEMs.

We gratefully
acknowledge the financial support of the
National Science Foundation of China (21476044, 21406031 and 21776034) and the Changjiang Scholars Program (T2012049).