Synthesis and Characterization of Alkali Metal Ion-Binding Copolymers Bearing Dibenzo-24-crown-8 Ether Moieties.

Dibenzo-24-crown-8 (DB24C8)-bearing copolymers were synthesized by radical copolymerization using a DB24C8-carrying acrylamide derivative and N-isopropylacrylamide monomers. The cloud point of the resulting copolymers changed in aqueous solution in the presence of cesium ions. In addition, the ¹H NMR signals of DB24C8-bearing copolymers shifted in the presence of alkali metal. This shift was more pronounced following the addition of Cs⁺ compared to Rb⁺, K⁺, Na⁺, and Li⁺ ions due to recognition of the Cs⁺ ion by DB24C8.