Synthesis of a thermo-sensitive copolymer with hydroxamic acid group and its characteristics of metal-ion collection

Thermo-sensitive copolymers, poly(N-isopropylacryl- amide-co-methacrylhydro xamic acid), were synthesized and studied concerning their characteristic p hase transition and collection of metal ions. As the molar feed ratio of hy droxamic acid group in the copolymer increased, the phase-transition temper ature (lower critical solution temperature) of the copolymer increased and the phase transition became difficult. The reason was that the introduction of hydroxamic acid group into the copolymer made the copolymer hydrophilic . The copolymers were dissolved in water homogeneously and were able to rea ct with metal ions. It was found that the metal ions could be collected by the copolymer without hydrolysis of the metal ion. Especially, Fe(III) ion was collected entirely in the 5.0 similar to 19.0 pH range. It was suggeste d that hydroxamic acid group in the copolymer did not form higher-order che lates.