Polymeric Sensor and Actuators; Synthesis and Characterization of Thiosemicarbazone-based Polymers

Abstract

Thiosemicarbazone Based Polymeric for the Sustained Release of a Model Drug via Selective Detection of Cu(II) ions The well-defined amphiphilic phenylthiosemicarbazone-based block copolymer was successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by post-polymerization modification. Poly(N,N-dimethylacrylamide) (pDMA) was synthesized via RAFT polymerization of N,N-dimethylacrylamide (DMA). The resulting pDMA macro chain transfer agent (macroCTA) was further chain extended with 3-vinylbenzaldehyde (VBA) to yield poly[(N,N-dimethylacrylamide)-b-(3-vinylbenzaldehyde)] p(DMA-b-VBA) block copolymer. The aldehyde group of p(DMA-b-VBA) was reacted with 4-phenylthiosemicarbazide to yield poly{N,N-dimethylacrylamide-b-[N-phenyl-2-(3-vinylbenzylidene)hydrazine carbothioamide]}, [p(DMA-b-PVHC)]. p(DMA-b-PVHC) was self-assembled in aqueous solution to yield polymeric micelles that consist of a pDMA block forming a hydrophilic shell and pPVHC block forming a hydrophobic core. p(DMA-b-PVHC) micelles can detect Cu(II) ions via color changes from colorless to yellow, induced by the formation of coordination complexes between Cu(II) ions and phenylthiosemicarbazone units of p(DMA-b-PVHC) micelles. The core of p(DMA-b-PVHC) micelles was crosslinked via the slow penetration of Cu(II) ions into the core, and the resulting particles with crosslinked ionic cores became swollen in water. Upon the addition of Cu(II) ions, the hydrophobic model drug, coumarin 102, encapsulated in the core of micelles was released in a sustained manner due to the gradual swelling of the crosslinked core achieved by the slow penetration of Cu(II) ions. |Thiosemicarbazone Based Water-Soluble Polymeric Probe for the Selective Sensing and Separation of Cu(II) Ions in Aqueous Media 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, [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 sensing behavior toward Cu(II) ions. P2 has remarkable pHswitchable sensing properties toward Cu(II) ions. Although efficient colorimetric sensing was observed at neutral or high pH, no appreciable color change appeared at low pH. Protonation of the imino nitrogen at low pH prevented the formation of coordination complexes. Cu(II) ions were separated successfully from various alkali and transition metal cations by thermal precipitation due to the thermoresponsive property of P2−Cu(II).We report the unique thermoresponsive properties of fluorinated polyacrylamides, poly[N-(2,2-difluoroethyl)acrylamide] (P2F). The solubility of fluorinated polyacrylamides in water can be easily controlled by changing the number of fluorine atoms in N-ethyl groups.Moreover, we demonstrate that fluorinated polyacrylamides are less cytotoxic than poly(N-isopropylacrylamide) (PNIPAM).

Thiosemicarbazone Based Polymeric for the Sustained Release of a Model Drug via Selective Detection of Cu(II) ions The well-defined amphiphilic phenylthiosemicarbazone-based block copolymer was successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by post-polymerization modification. Poly(N,N-dimethylacrylamide) (pDMA) was synthesized via RAFT polymerization of N,N-dimethylacrylamide (DMA). The resulting pDMA macro chain transfer agent (macroCTA) was further chain extended with 3-vinylbenzaldehyde (VBA) to yield poly[(N,N-dimethylacrylamide)-b-(3-vinylbenzaldehyde)] p(DMA-b-VBA) block copolymer. The aldehyde group of p(DMA-b-VBA) was reacted with 4-phenylthiosemicarbazide to yield poly{N,N-dimethylacrylamide-b-[N-phenyl-2-(3-vinylbenzylidene)hydrazine carbothioamide]}, [p(DMA-b-PVHC)]. p(DMA-b-PVHC) was self-assembled in aqueous solution to yield polymeric micelles that consist of a pDMA block forming a hydrophilic shell and pPVHC block forming a hydrophobic core. p(DMA-b-PVHC) micelles can detect Cu(II) ions via color changes from colorless to yellow, induced by the formation of coordination complexes between Cu(II) ions and phenylthiosemicarbazone units of p(DMA-b-PVHC) micelles. The core of p(DMA-b-PVHC) micelles was crosslinked via the slow penetration of Cu(II) ions into the core, and the resulting particles with crosslinked ionic cores became swollen in water. Upon the addition of Cu(II) ions, the hydrophobic model drug, coumarin 102, encapsulated in the core of micelles was released in a sustained manner due to the gradual swelling of the crosslinked core achieved by the slow penetration of Cu(II) ions.