Ion-Exchange Properties as a Function of Polymer Chain Network Properties

Abstract

Porous crosslinked polymers carrying sulfonic acid groups were prepared with varying degrees of crosslinking and pore structures. The ratio of number of macropores (here named “fixed pores”) to total number of pores was named fixed pore ratio φ_ih; pore structures were characterized by this φ_ih. Ion exchange properties of synthesized cation exchangers were found to be different according to the physical structures of polymers. Polymers with high φih (compact polymer phase and high crosslinkings density) were found to show very slow ion exchange rates. In the Nd³⁺/Pr³⁺ system using the polymer with φ_ih=0.94, the degree of conversion after 60min was 0.622 and about 40% of counter ions did not exchange. From these phenomena, we concluded that rigid and unflexible polymer chains formed very stable trapping field partially in the ion exchange site.