Water-Soluble Polymeric Probe for the Selective Sensing and Separation of Cu(II) Ions in Aqueous Media: pH-Tunable Detection Sensitivity and Efficient Separation by Thermal Precipitation

A thiosemicarbazone-based water-soluble polymeric probe was developed for the selective colorimetric detection of Cu(II) ions with pH-tunable sensitivity. The successful separation of Cu(II) ions from several alkali and transition metal cations by thermal precipitation was demonstrated. N,N-Dimethylacrylamide (DMA) and 3-vinylbenzaldehyde (VBA) were copolymerized by reversible addition–fragmentation chain transfer (RAFT) polymerization to produce p(DMA-co-VBA), herein P1. The aldehyde group of P1 was reacted with 4-phenylthiosemicarbazide to yield poly{DMA-co-[N-phenyl-2-(3-vinylbenzylidene)hydrazinecarbothioamide]}, [p(DMA-co-PVHC)], herein P2. Upon the addition of Cu(II) ions to an aqueous solution of P2, the color of the solution turned from colorless to yellow due to the formation of a coordination complex between the Cu(II) ions and phenylthiosemicarbazone units of P2, herein P2–Cu(II). The availability of the electron-rich imino nitrogen in the thiosemicarbazone units allowed P2 to show excellent se...