The figure below shows $4$ ion exchange polymers. Specify whether they are anion or cation exchange polymers, give the name$($s$)$ of the

exchange site$($s$),$ compare a priori the different polymers in terms of stability thermal$/$chemical$/$mechanical$,$ water content and ion exchange

capacity.

$($a$)$

$($b$)$

$($c$)$

$($d$)$